WO2025068795A2

WO2025068795A2 - Ultrasonic cleaning of stir chamber for agricultural sample slurry

Info

Publication number: WO2025068795A2
Application number: PCT/IB2024/058337
Authority: WO
Inventors: Kent LEVY; Reid HARMAN
Original assignee: Precision Planting LLC
Current assignee: Precision Planting LLC
Priority date: 2023-09-29
Filing date: 2024-08-28
Publication date: 2025-04-03
Anticipated expiration: 2026-03-29
Also published as: WO2025068795A3

Abstract

In one embodiment, a system for processing an agricultural slurry is disclosed. The system includes a stirring device having a stir chamber and one or more outlet ports to release slurry from an internal cavity. The stirring device further includes a filter fluidly coupled to the one or more outlet ports and positioned inside the internal cavity of the stir chamber to filter the slurry. An ultrasonic transducer is positioned proximate to or in physical contact with the filter to clean the filter.

Description

Attorney Docket No.23162/WO ULTRASONIC CLEANING OF STIR CHAMBER FOR AGRICULTURAL SAMPLE SLURRY CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application Nos. 63/586656, filed 29 September 2023; 63/586672, filed 29 September 2023; 63/586702, filed 29 September 2023, all of which are incorporated herein by reference in their entireties. BACKGROUND [0002] The present disclosure generally relates to agricultural sampling and analysis, and more particularly to ultrasonic cleaning of a stir chamber that stirs an agricultural material sample such as soil. [0003] Periodic soil testing is an important aspect of the agricultural arts. Test results provide valuable information on the chemical makeup of the soil such as plant-available nutrients and other important properties (e.g., levels of nitrogen, magnesium, phosphorous, potassium, pH, etc.) so that various amendments may be added to the soil to maximize the quality and quantity of crop production. [0004] In some sampling and chemical analysis processes, the raw or bulk agricultural material samples such as soil (or other agricultural materials) extracted from the field may be prepared for analysis. The devices uses to prepare the soil for analysis may require cleaning between uses. BRIEF SUMMARY [0005] The present disclosure provides a system, device, and method for cleaning a stir chamber that stirs an agricultural material. In one embodiment, a system for processing an agricultural slurry is disclosed, the system comprising a source of an agricultural sample slurry; a stirring device comprising a stir chamber comprising a housing defining an internal cavity configured to receive an agricultural sample slurry; one or more outlet ports configured to release slurry from the internal cavity; and a filter fluidly coupled to the one or more outlet ports and positioned inside the internal cavity of the stir chamber to filter the slurry; and an ultrasonic transducer positioned proximate to or in physical contact with the filter. Attorney Docket No.23162/WO [0006] In another aspect, an ultrasonic transducer for causing cavitation bubbles to form in a liquid is disclosed, the ultrasonic transducer comprising a front driver element; a back driver element; two piezoelectric elements positioned between the front driver element and the back driver element; a bolt configured to pass through at least a portion of each of the front driver element, the back driver element, and the two piezoelectric elements; and an insulation sleeve surrounding a portion of the bolt to prevent the bolt from contacting the two piezoelectric elements, the insulation sleeve comprising a dielectric material; wherein the ultrasonic transducer vibrates along a first axis; wherein the front driver element has a front portion proximate to the front end of the ultrasonic transducer and an opposite rear portion; and wherein a cross sectional area of the front portion of the front driver element is smaller than a cross sectional area of the rear portion of the front driver, where each of the cross sectional areas is perpendicular to the first axis. [0007] In another aspect, a method for cleaning a filter of a stirring device for an agricultural sample slurry is disclosed, the method comprising positioning an ultrasonic transducer proximate to or in physical contact with the filter of the stirring device; stirring an agricultural sample slurry in a stirring device, the stirring device comprising a filter; and activating the ultrasonic transducer to clean the filter. [0008] Although the stir chamber apparatus, system, and related methods or processes for preparing an agricultural sample slurry may be described herein with reference to soil samples for convenience of description, this represents only a single category of use for the disclosed embodiments of the invention. It will therefore be understood that the same apparatus and related methods or processes may be used for processing any type of sample, not limited to agricultural samples. These samples may include any liquid, including liquid solutions and suspensions. The disclosure herein should therefore be broadly construed as an apparatus and related methods or processes for analyzing the sample regardless of the type of material or method of collection. BRIEF DESCRIPTION OF THE DRAWINGS [0009] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein like elements are labeled similarly and in which: [0010] FIG. 1 is a schematic of an exemplary system for analyzing an agricultural sample; [0011] FIG. 2 is a perspective view of a stir chamber as may be used in the exemplary system for analyzing an agricultural sample as shown in FIG. 1; [0012] FIG. 3 is a cross sectional view of the stir chamber of FIG. 2, taken along line 3-3; Attorney Docket No.23162/WO [0013] FIG. 4 is a cross sectional view of the stir chamber of FIG. 3, taken along line 4-4; [0014] FIG. 5 is a cross sectional view of the stir chamber of FIG. 2, taken along line 5-5; [0015] FIG. 6 is a cross sectional view of the stir chamber of FIG. 2, taken along line 6-6; [0016] FIG.7 is a schematic view of an alternate embodiment of a stir chamber as may be used in the system of FIG. 1; [0017] FIG. 8 is a flow chart illustrating a method for analyzing a sample; [0018] FIG. 9 is a schematic system block diagram of an alternative system for processing analyzing an agricultural sample; [0019] FIG. 10 is a first top perspective view of a stirring device of the system of FIG. 9 comprising a stir chamber for processing and analyzing an agricultural sample slurry; [0020] FIG. 11 is a second top perspective view thereof; [0021] FIG. 12 is a first bottom perspective view thereof; [0022] FIG. 13 is a second bottom perspective view thereof; [0023] FIG. 14 is a first side view thereof; [0024] FIG. 15 is a second side view thereof; [0025] FIG. 16 is a third side view thereof; [0026] FIG. 17 is a fourth side view thereof; [0027] FIG. 18 is a top view thereof; [0028] FIG. 19 is a bottom view thereof; [0029] FIG. 20 is a first longitudinal cross sectional view thereof; [0030] FIG. 21 is an enlarged detail from FIG. 20; [0031] FIG. 22 is a second longitudinal cross sectional view of the stirring device of FIG. 10; [0032] FIG. 23 is an enlarged detail from FIG. 22; [0033] FIG. 24 is transverse cross sectional view of the stir chamber of the stirring device; [0034] FIG. 25 is an isometric view of an ultrasonic transducer positioned proximate to a filter of a stir chamber according to one embodiment. [0035] FIG. 26 is a cross sectional view of the ultrasonic transducer of FIG. 25 taken along line 26-26 where the ultrasonic transducer is mounted to a housing of the stir chamber; [0036] FIG. 27 is a front view thereof; [0037] FIG. 28 is an isometric view of the ultrasonic transducer of FIG. 25 separate from the stir chamber; Attorney Docket No.23162/WO [0038] FIG. 29 is an exploded view of the ultrasonic transducer of FIG. 25 without its housing; [0039] FIG. 30 is an isometric view of an ultrasonic transducer positioned proximate to a filter of a stir chamber according to a second embodiment. [0040] FIG. 31 is a cross sectional view of the ultrasonic transducer of FIG. 30 taken along line 31-31 where the ultrasonic transducer is mounted to a housing of the stir chamber; [0041] FIG. 32 is a front view thereof; [0042] FIG. 33 is an isometric view of the ultrasonic transducer of FIG. 30 separate from the stir chamber; and [0043] FIG. 34 is an exploded view of the ultrasonic transducer of FIG. 30 without its housing. [0044] FIG.35 is a flowchart for a method of cleaning a filter of a stirring device for an agricultural sample slurry according to one embodiment. [0045] All drawings are schematic and not necessarily to scale. Components numbered and appearing in one figure but appearing un-numbered in other figures are the same components unless expressly noted otherwise. Any reference herein to a figure by a whole figure number which may appear in multiple figures bearing the same whole number prefix but with different alphabetical suffixes shall be construed as a general reference to all of those figures unless expressly noted otherwise. DETAILED DESCRIPTION [0046] The features and benefits of the present disclosure are illustrated and described herein by reference to exemplary (“example”) embodiments. This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. Accordingly, the disclosure expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features. [0047] In the description of embodiments disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present disclosure. Relative terms such as "lower," "upper," “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or Attorney Docket No.23162/WO operated in a particular orientation. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. [0048] As used throughout, any ranges disclosed herein are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein to prior patents or patent applications are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. [0049] FIG. 1 illustrates a schematic view of a system for analyzing an agricultural sample 100. The system 100 comprises a grinder 110, a stir chamber 200, a pump 120, a filter 130, and an analysis unit 140. The grinder 110 receives an agricultural sample, such as soil, and grinds the sample to ensure that the maximum particle size of the agricultural sample is below that required for later analysis by the analysis unit 140. For instance, clumps of soil and plant matter may be ground to reduce them in size so that they are suitable for passing through the system. In addition, water may be added from a fluid source to facilitate effective grinding and provide a liquid slurry that eases passage of the sample through the system and is ultimately used for final analysis by analysis unit 140. [0050] The sample (i.e. slurry) then passes from the grinder 110 to the stir chamber 200. The purpose of the stir chamber 200 is to ensure that the agriculture sample is homogeneous. This may be performed by a variety of methods, including mixing, stirring, shaking, vibrating, or any other means suitable to ensure thorough mixing of the sample. In addition, measurements may be performed on the sample to verify that adequate mixing has occurred. For instance the level of the sample within the stir chamber 200, the density, or the mass may be measured in an effort to determine adequate sample size and homogeneity. Once again, water may be added from a fluid source to achieve a target density, improve homogeneity, or other purposes. The fluid source may recycle water used elsewhere in the process or may add new water. In addition, the sample may be returned to the stir chamber from downstream components to perform additional processing as will be discussed in greater detail below. [0051] From the stir chamber 200, the sample passes to a pump 120. The pump 120 pressurizes the sample to ensure that it is effectively filtered by a filter 130. In other implementations, the Attorney Docket No.23162/WO pump 120 may be located downstream of the filter 130, such that the filter 130 is on the suction side of the pump 120. The pump 120 and filter 130 may be used to remove undesirably large components of the sample such as gravel that have passed through the grinder. The pump 120 and filter 130 may also be used to recirculate a portion of the sample along with additional water from a water source to enable additional treatment and adjustment of the sample slurry in the stir chamber 200. This may be done because only a portion of the sample is required for further testing. It is also possible to iteratively adjust the density, water/solids ratio, and homogeneity of the sample to facilitate further analysis. [0052] Once the sample has passed through the filter 130, the analysis unit 140 performs further analysis on some or all of the sample. This analysis may include measurement of physical properties such as density or mass. The analysis may also include a range of chemical analyses. Subsequently, the sample may be discarded. Additional water from one or more of the fluid sources may be used to flush the system and ensure accurate measurement of a future sample. [0053] A controller 300 controls all functions of the stir chamber 300. The controller 300 comprises a memory 310, a processor 320, and a device interface 330. The controller 300 may be a central controller which controls functions for all components of the system. In other implementations 300, the controller 300 may be integrated into a single component such as the stir chamber 200. In this implementation, additional controllers 300 may be integrated into the other components and may communicate via a bus or other communications system. Alternately, the controller 300 may be integrated into a single component and may also connect to other components in the system. As can be seen, the arrangement of the controller 300 may be distributed or may be centralized as desired. [0054] Turning to Figs. 2-6, an exemplary embodiment of a stir chamber 200 is illustrated. The stir chamber has a housing 220 formed of a gear head 221, an upper housing 222, a middle housing 223, and a lower housing 224. The gear head 221 receives a motor 225 and couples to the upper housing 222. The upper housing 222, middle housing 223, and lower housing 224 collectively form an internal cavity 230. The internal cavity 230 extends along a longitudinal axis A-A, the internal cavity 230 being elongate along the longitudinal axis A-A. The internal cavity 230 extends along the longitudinal axis A-A from a top end 231 to a bottom end 232. [0055] A plurality of ports 240 are formed into the housing 220 and are fluidly coupled to the internal cavity 230. The ports 240 may serve a variety of functions, including receiving a sample, Attorney Docket No.23162/WO outputting a sample, permitting sensors to measure the sample, allowing for injection of fluid such as water from a fluid source, or any other desired function. Optionally, some of the ports 240 may be plugged and may be utilized for optional functions which are not implemented in every system. [0056] The stir chamber 200 further incorporates an agitator 250. The agitator 250 collectively comprises the motor 225, a gear train 251, and two agitator shafts 252. In other embodiment, only one agitator shaft may be used. Each of the exemplified agitator shafts 252 comprises a blade 253 that agitates the sample when the agitator shafts 252 are rotated. The gear train 251 connects the motor 225 to the agitator shafts 252. Optionally, more than one motor 225 may be utilized and the gear train 251 omitted. Optionally, one agitator shaft 252 or more than two agitator shafts 252 may be utilized. In yet other configurations, the gear train 251 may be formed as a belt or chain drive instead of a gear drive, but may still be referred to as a gear train 251. The gear train 251 may serve to reduce or increase the speed of the agitator shafts 252 with respect to the motor 225, or the gear train 251 may provide no reduction or multiplication of the speed of the motor 225. [0057] The signals from the sensors 210 are received by the controller 300. The signals from the sensors 210 may be in the form of an analog voltage or current, or may be a digital signal. The signals from the sensors 210 correspond to a parameter measured by the respective sensor 210. The signals may vary with respect to time, and may represent a parameter such as pressure or some other parameter which is continuously changing based on the measured condition at the respective sensing port. [0058] Next, the internal cavity 230 is filled with a fluid of unknown density such as the agricultural sample. Once again, the two locations must be covered by the fluid of the sample. The pressure differential between the two locations is once again measured to determine a specimen differential pressure. The density may be calculated by the following formula: specimen density = reference density * specimen differential pressure / reference differential pressure. For example, if the reference density is arbitrarily assigned a value of 1, the specimen density can be determined with reference to the reference density. Specimens being twice as dense as the reference fluid would have a specimen density of 2, while specimens having half the density of the reference fluid would have a specimen density of 0.5. Alternately, the density may be defined in terms of any accepted unit system. For instance, density may be defined in terms of grams per cubic centimeter, kilograms per cubic meter, pounds per cubic foot, or any other recognized unit system. Attorney Docket No.23162/WO [0059] In the event that a reference fluid of known density is not available, the internal volume and location of the sensing ports 241, 242, 243 can be utilized to calculate an expected pressure differential between two ports of a given reference fluid. This can, in turn, be used to compute a theoretical reference differential pressure that may be utilized to calculate the specimen density using the same equation as is used when an actual reference fluid is used. However, this suffers from some potential loss of accuracy due to variations in internal volume of the internal cavity 230, variations in the location of the sensors 210, and other variables. [0060] Furthermore, a method of determining the mass of the sample can be performed. If the geometry and volume of the internal cavity 230 are known, it is possible to determine the mass of liquid within the region between the two measured points. For instance, in a cylindrical volume, the mass within the internal cavity 230 in the region between the two measured points can be determined by multiplying the specimen density by the volume within the region between the two measured points. [0061] In yet another method, the sensors 210 can be utilized to determine a level of the sample within the internal cavity 230. By comparing the pressure measured by each sensor 210 against atmospheric pressure, the presence or absence of the sample can be determined for each location. In addition, it is possible to calculate a level between the sensors 210 by combining density measurements with pressure measurements. For instance, if the sensor 210 at the first sensing port 241 measures a pressure equal to atmospheric pressure, then the sample must have a level below the location of the first sensing port 241 with respect to the longitudinal axis A-A. If the sensor 210 at the first sensing port 241 measures a pressure greater than atmospheric pressure, then the sample must have a level above the location of the first sensing port 241. In combination with the pressure and density information, a level between ports 240 can be extrapolated. If additional sensing accuracy is desired, additional sensing ports may be added or additional sensors 210 of different types may be utilized. [0062] In yet a further method, information regarding the density within regions of the internal cavity 230 may be used to measure the homogeneity of the sample. Where the sample is an inhomogeneous liquid (i.e. a thin suspension or other liquid of non-uniform density), measuring at three or more points will provide information on the distribution of the density of the sample in three or more regions. Attorney Docket No.23162/WO [0063] For example, in the present system, the density of the sample can be measured in the first region R1 between the sensor 210 at the first sensing port 241 and the sensor 210 at the second sensing port 242. The density may also be measured in the second region R2 between the sensor 210 at the second sensing port 242 and the sensor 210 at the third sensing port 243. Finally, the density may be measured in the third region R3 between the sensor 210 at the first sensing port 241 and the sensor 210 at the third sensing port 243. Thus, the density can be measured for the first and second regions R1, R2 and the third region R3 that overlaps both the first and second regions R1, R2. Adding additional sensors 210 at additional sensing ports will allow measurements in additional regions, further increasing the information regarding the homogeneity of the sample. [0064] As can be seen, each of the first, second, and third regions R1, R2, R3 may have different densities. The difference between the densities of the first, second, and third regions R1, R2, R3, allows a quantitative analysis of the homogeneity of the sample within the internal cavity 230. In some implementations, the agitator 250 may be activated in response to detecting a difference in density between two regions that exceeds a predetermined threshold. [0065] In yet other implementations, where the sample has a greater density in the first region R1 than either the second or third regions R2, R3, the speed of the agitator shafts 252, or by extension, the speed of the motor 225, may be reduced to allow particles or other components of the sample to settle toward the bottom end 232 of the internal cavity 230. Where the sample has a lesser density in the first region R1 than either the second or third regions R2, R3, the speed of the agitator shafts 252, or by extension, the speed of the motor 225, may be increased to increase agitation and move particles from the second region R2 to the first region R1. [0066] In each case, the speed of the agitator shafts 252 may be controlled using proportional control or may be activated according to a series of predetermined thresholds, with each threshold corresponding to a difference in density. In other implementations, the speed may be controlled in any known means designed to improve homogeneity of the sample. Any number of regions may be created by any number of sensors 210 as desired. [0067] In other implementations, the sensors 210 need not be located in sensor ports as shown in the embodiment of Figs. 2-6. In other implementations such as that shown schematically in Fig. 7, the sensors 210 may measure pressure at different locations using tubes or probes. Each tube of the sensors 210 terminates at a different location with respect to the longitudinal axis A-A to Attorney Docket No.23162/WO permit measurement at different heights just as with the embodiment of Figs. 2-6. Otherwise stated, the tube of each sensor 210 terminates at a first, second, or third sensing port 241, 242, 243. A particle distribution within the sample is illustrated as having a different distribution with respect to position along the longitudinal axis A-A. [0068] The use of an agitator 250 is optional. In some implementations, the agitator 250 may be omitted and density or fluid level measurements may be made without use of the agitator 250. In yet other implementations, the sample need not have suspended solids, but instead may be any fluid, either homogeneous or inhomogeneous. [0069] In summary, a method for analyzing a sample 400 starts with step 410, providing a chamber 200 having an internal cavity 230. The internal cavity 230 extends along a longitudinal axis from a bottom end 232 to a top end 231. In step 420, a first sensor 210 is fluidly coupled to the internal cavity 230 at a first location with respect to the longitudinal axis A-A. A second sensor 210 is fluidly coupled to the internal cavity 230 at a second location with respect to the longitudinal axis A-A. Optionally, a third sensor 210 is fluidly coupled to the internal cavity 230 at a third location with respect to the longitudinal axis A-A. Each of the first, second, and third locations are different, and may be spaced from one another along the longitudinal axis A-A. [0070] Subsequently, in step 430, a sample is added to the internal cavity 230. In step 440, a plurality of signals from the sensors 210 are read by the controller 300. In step 450, a density or fluid level of the sample is determined via the plurality of signals from the sensors 210. Optionally, the sensors 210 may be pressure sensors 210. Optionally, more than one density may be determined for different regions located between any two sensors as discussed above. In yet further optional configurations, the agitator 250 may be operated to increase or decrease agitation in response to the measured density in one or more different regions. [0071] Alternative Slurry Density Measurement System and Related Method [0072] FIGS.9-24 show an alternative embodiment of a slurry density measurement system. The system generally includes a stirring device 500 generally similar to the stirring device with stir chamber 200 and agitator 250 operable to stir the slurry, as previously described herein. Reference is made to the prior description for details which is not repeated here in full for the sake of brevity. The following description of the present stirring device will focus on the differences in the two designs which are pertinent. Attorney Docket No.23162/WO [0073] In contrast to stir chamber 200 of the prior stirring device, the stir chamber 502 of present stirring device 500 is configured differently in part for determining the density of the agricultural sample slurry in a different manner without use of pressure sensing ports 240 and related pressure sensing equipment. Instead, the present stirring device comprises a mechanically isolated stir chamber 502 configured to receive the agricultural sample slurry from grinder 110 and gently agitate the slurry to keep the majority of agricultural solids (i.e. particles) in suspension for purposes of obtaining slurry density and other related measurements. The sample slurry may be a soil slurry in one non-limiting embodiment. [0074] The present mechanically isolated stir chamber 502 is formed by a section of the stirring device housing that is mechanically isolated from other portions of the stirring device and related appurtenances interfaced with the stir chamber such as the slurry inlet and outlet. Accordingly, the weight of the stir chamber is solely supported independently of other portions of the stirring device and related system by a load cell, such as without limitation a strain gauge 504 in one embodiment which is rigidly mounted to an available support structure. As further described herein, this allows an accurate weight of the stir chamber 502 to be measured empty and when filled with slurry; the difference representing the weight of the volume of slurry in the chamber. This information is used in conjunction with other measurements described below to determine the overall density of the slurry and water/solids ratio of the slurry. [0075] Referring now in general to FIGS. 9-24, present stirring device 500 generally comprises a vertically elongated partially hollow housing 510 which may include an upper housing section 511 and lower housing section 512. Upper housing section 511 mounts and supports the agitator mechanism including agitator 250 driven by motor 225 and gear train 251, as previously described herein. In the present embodiment, however, the agitator may include only a single rotatable agitator shaft 252 and blade 253 assembly which is supported from above by upper housing section 511 in an overhead suspended manner as shown. It bears noting that two shaft and blade assemblies may be used in alternative embodiments if necessary for adequate agitation of the slurry to keep solid in suspension depending on the nature of the slurry. The agitator shaft is supported by the upper housing section of the stirring device independently of the stir chamber. In some embodiments, the agitator shaft 252 and blade 253 may be directly driven by the motor such that the gear train may be omitted. Attorney Docket No.23162/WO [0076] Although the mode of agitation disclosed uses a single agitator shaft and blade assembly hanging down into the stir chamber 502 from upper housing section 511, other modes of agitating the slurry may be used in other embodiments, including for example but not limited to pneumatic agitation (bubbling air up into the internal cavity 530 of the stir chamber through the slurry), and recirculating the sample slurry through a separate pumped slurry flow loop. [0077] Lower housing section 512 defines the stir chamber 502 which includes internal cavity 530 configured for holding a volume of coarsely filtered slurry (or filtrate) received from grinder 110. Agitator shaft 252 and blade 253 assembly is positioned inside internal cavity 530, but not supported in any manner by the lower housing section 512. Upper housing section 511 provides sole support for the agitator shaft and blade assembly which enters the open top end 531 of the stir chamber internal cavity. Stir chamber 502 further includes a slurry inlet port 540 proximate to the top end of internal chamber 530 and a waste port 543 at the bottom or floor 530a of internal cavity 530. [0078] Notably, the stir chamber 502 defined by lower housing section 512 may be mechanically isolated from the upper housing section 511 in one embodiment via an isolation air gap 506 formed therebetween. An annular isolation air gap 508 may also be provided to also mechanically isolate the slurry inlet conduit 541 (e.g., section of piping or tubing) from the slurry inlet port 540 of the stir chamber. This prevents any support of the stir chamber by the slurry inlet conduit. The inlet conduit may be rigid in construction and could otherwise adversely affect obtaining an accurate stir chamber weight measurement by strain gauge 504. A slip joint may be used for the slurry inlet connection which incorporates the annular isolation air gap 508 as shown. The slurry inlet conduit is supported independently from the stir chamber 502 via a separate mounting bracket 541a attached to an available support structure. [0079] Lower housing section 512 includes a support bracket 505 configured to fixedly couple the lower housing section (i.e. stir chamber) to one end 504a of the strain gauge 504 in a cantilevered manner as shown. Support bracket 505 may be mounted to one lateral side of the lower housing section. The opposite end 504b of the strain gauge is fixedly coupled to an available support structure, which in one embodiment may be provided by a portion of bracket 507 rigidly coupled to upper housing section 511. Other available support structures may be used to coupled end 504b of strain gauge configured 504 thereto which are not connected to the upper housing section. The strain gauge 504 may have a horizontally elongated structure as shown in one embodiment. Attorney Docket No.23162/WO Mechanical fasteners such as threaded fasteners in one non-limiting embodiment may be used to couple the strain gauge to bracket 507 and lower housing section 512 (i.e. stir chamber). Other types of mechanism fasteners such as rivets, clamps, etc. may be used. Other types of load sensors operable to measure the weight (mass) of the stir chamber and able to structurally support the stir chamber independently of the stirring device upper housing section in the manner described herein may be used. [0080] It bears noting that the strain gauge readings are sensitive to forces and vibration coming from outside the sample slurry stir chamber 502. Mechanically isolating the stir chamber 502 from the rest of the stirring device via the isolation air gap 506 previously described herein prevents or minimizes such disturbances. In addition, any wires, flow conduits (tubing, piping, etc.) or other appurtenances that must still be connected to the sample chamber are preferably strain relieved nearby (i.e. self supported without reliance on the stir chamber for support) so that they cannot support or “push” or “pull” on the stir chamber system in any manner which could adversely affect accurate slurry weight/mass measurements by strain gauge 504. An example of this is slurry inlet mounting bracket 541a previously described herein. These support measures external to the stir chamber help ensure the accuracy of the strain gauge weight/mass measurements. [0081] The load cell (e.g., strain gauge 504) is used to measure the weight (mass) of the slurry inside the stir chamber by determining the differential weight between an empty stir chamber and then again when filled with slurry; the difference representing the weight of the slurry alone. To determine the density of the slurry, the volume of slurry must also be determined (density being a measure of the mass per unit volume of material). In one embodiment, a level sensor 515 may be provided to determine the volume of slurry in stir chamber 502. [0082] Level sensor 515 may be a non-contact type level sensor in one embodiment such as a ultrasonic transducer or similar; however, other type level sensors including contact level sensors could be used if appropriate. Sensor 515 may be mounted to upper housing section 511 and has a line of sight directly into internal cavity 530 of the stir chamber 502 through the open top end to of the chamber in order to detect a surface level of the slurry, which is correlated to the height of the column of slurry in the stir chamber via controller 300. Since the dimensions of the stir chamber internal cavity 530 are precisely known, the volume of slurry held therein at any given time can be readily determined as a function of the height of the column of slurry present. This Attorney Docket No.23162/WO information can be preprogrammed into controller 300 for use in determining the volume of slurry based on the slurry level detection (height of slurry column). [0083] The accuracy and repeatability of the volume measurements via level sensor 515 is dependent on the cleanliness of the sensor. So the sensor in one embodiment is preferably mounted in upper housing section 511 of stirring device 500 as far removed from the surface of the liquid slurry in the stir chamber 502 as possible to avoid being splashed when the slurry is agitated. In one embodiment, a downwardly open sensor cavity 515a recessed into the bottom of upper housing section 511 may be provided to maximize the distance of the sensor from the surface level of the sample slurry. [0084] The density of the slurry can be determined by dividing the total mass of slurry (weight) measured via strain gauge 504 by the volume of slurry determined via level sensor 515. In one embodiment, the density can be calculated automatically by programmable controller 300 shown in the modified system block diagram of FIG. 9. Strain gauge 504 and level sensor 515 are operably and communicably linked to controller 300, which is programmed with the appropriate program instructions (e.g., control logic) to calculate the density of the slurry based on the measured weight (mass) and calculated volume of the slurry based on slurry level measurement. [0085] In one embodiment, a method for automatically determining density of the agricultural sample slurry via controller 300 may comprise the following steps implemented by the controller. [0086] First, the controller 300 measures the weight of the stir chamber 502 in an empty condition any time before the start of a sample slurry processing run without slurry present in the chamber. This provides a first empty stir chamber weight. Next, an amount (volume) of slurry is added to the stir chamber (e.g., internal cavity 530) via slurry inlet port 540, such as from the grinder 110 as shown in FIG. 9. The may be done via controller opening isolation valve 525 (or manually) in the flow conduit between grinder 110 and stir chamber 502 (represented by the solid flow arrows). Valve 525 is then closed to fluidly isolate the grinder from the stir chamber and controller 300. The controller measures the weight of stir chamber 502 with slurry filled in the internal cavity 530. This provides a second filled stir chamber weight. The slurry may be agitated via agitator 250 before or after the measurements is taken, but preferably not during slurry weight and level measurements. [0087] Next, the controller next calculates/determines the actual weight of the slurry by comparing and subtracting the empty stir chamber weight from the filled stir chamber weight. This represents Attorney Docket No.23162/WO the mass of slurry present in the stir chamber. It bears noting that the mass of slurry added to the stir chamber 502 may initially be unknown. The weight of the slurry is determined by controller 300 based on the actual volume of slurry present in the stir chamber 502. [0088] Controller 300 also automatically determines the volume of sample slurry present in stir chamber 502 via level sensor 515, either before, after, or simultaneously with the step of determining the mass (weight) of the slurry. Level sensor 515 is activated by the controller to measure the level of the slurry in stir chamber 502. [0089] Controller 300 has been preprogrammed with data related to the volume of slurry present in stir chamber internal cavity 530 as a function of the height of the slurry column represented by the slurry level measurement, such as via a lookup table or appropriate equation. The controller executes a routine to readily correlate the level of the slurry measured in real-time (via detecting the top surface of the slurry) to a corresponding representative volume of slurry present based on the height of the slurry column detected. It is well within the ambit of those skilled in the art to program the controller with the appropriate data and software instructions to make the correlation between measured slurry surface level and volume. [0090] Finally, with both the slurry mass and volume parameters determined, controller 300 calculates the overall density of the slurry based on the slurry weight/mass and slurry level measurements obtained by the strain gauge and level of the entire slurry sample in stir chamber 502. This recognizes that the slurry is not an ideally homogenous mixture, so that measuring the entire slurry sample averages out areas of lower or higher density in the slurry mass. It bears noting that the slurry weight and level measurements are preferably performed when the agitator 250 is not in operation so that the slurry is in a still and stable condition. This is desirable to ensure that accuracy for the slurry level detection and the weight/mass measurements. The forces exerted by the agitator, the sloshing of the sample slurry, and the body of the agitator itself could shift these measured values rendering them inaccurate. [0091] According to another aspect, stirring device 500 further includes a spectrometer 550 to determine the water/solids ratio of the agricultural sample slurry. Spectrometer 550 is operably coupled to programmable controller 300 as shown in FIG. 9. The spectrometer may be mounted proximate to the bottom end of stir chamber 502, and in one non-limiting embodiment as illustrated may be mounted on the underside the chamber to maximize the spectrometer’s exposure to heavier-than-water particles in the sample slurry, which tend to settle to the bottom of the chamber. Attorney Docket No.23162/WO Spectrometer 550 comprises a lens 551 fluidly sealed to stir chamber 502 to give the spectrometer a line of sight directed upwards into internal cavity 530 of the stir chamber. [0092] The spectrometer 550 is configured and operable to measure reflectivity of the sample slurry in the stir chamber. More particularly, spectrometer 550 in one aspect is operable for measuring particle density (grams per milliliter) of the solids in the slurry. Based on the reflectivity measurement of the sample solids in stir chamber 502, physical properties of the sample material can be determined, including the density of the solids (particles) in suspension in the sample slurry. Knowing the density of the water (≈0.998 mL/g) and the measured density of the solids particles e.g., soil or other) in suspension, controller 300 may be programmed to automatically calculate the water/solids ratio. The soil particle density can be predicted and correlated to the reflectivity measurements of the sample via experimental methods, which is well within the ambit of those skilled in the art. This information can form the basis for programming controller 300 to make the correlation between reflectivity and particle density automatically. [0093] Accordingly, using the slurry sample’s particle density measured by spectrometer 550 obtained from several reflectivity measurements and the density of the sample slurry determined by controller 300 discussed above, the current actual ratio of water mass to sample solids (particles) mass in the sample slurry (e.g., water/solids) can further be determined by controller 300 based on the reflectivity readings. Based on the real-time or actual current ratio, the controller 300 will automatically adjust the sample slurry in stir chamber 502 as needed until the desired target water/solids ratio has been reached which is optimized for analysis of the sample in the chemical/property analysis unit 140 of the system (see, e.g., FIG. 9). This includes adding more water to dilute the slurry, or more slurry to increase the amount of solids in suspension in the slurry. The solids may be soil for a soil sample, or any other agricultural or farm-related solid to be analyzed by the system. [0094] One non-limiting embodiment of the process implemented by controller 300 to achieve the desired target water/solids ratio (i.e. mass ratio) based on reflectivity measurements collected by spectrometer 550 may include but is not limited to the following control steps. Step (1): Determining a real-time or actual current water/solids ratio based on reflectivity measurements of the sample recorded by spectrometer 550. Step (2) Comparing the actual water/solids ratio to a preprogrammed target water/solids ratio for the sample slurry. Step (3) Adjusting the actual water/solids ratio to meet the target water/solids ratio. For example, if the actual water/solids ratio Attorney Docket No.23162/WO is less than the target water/solids ratio, controller 300 adds water to the stir chamber 502 (via slurry inlet port 540, a separate water inlet port, or a slurry recirculation inlet port) and repeating steps (1) and (2) one or more times until the controller 300 determines that the target water/solids ratio in the sample slurry is met. For example, the controller will initiate a process to add water to stir chamber 502 if the actual current water/solids ratio is less than the target ratio (i.e. more dilution water is needed in the slurry). Conversely, if the actual current water/solids ratio is greater than the target, more slurry (with entrained solids) is needed to reduce the water dilution of the slurry and increase its solids content. So controller 300 may briefly open isolation valve 525 to add an additional amount of slurry from grinder 110 into stir chamber 502. Steps (1) and (2) are again repeated as needed until the target ratio is met. [0095] A predetermined +/- variance in the target water/solids ratio may be programmed into controller 300 in some embodiments when permissible so that a measured actual water/solids ratio may be considered to meet the target water/solids ratio for purposes of the sample analysis if not greater or less than a programmed tolerance percentage. Accordingly, an acceptable target range of water/solids ratio may be used by the controller in some embodiments in lieu of a single absolute value for the target ratio. [0096] It bears noting that in certain embodiments, the pump 120 which takes suction for stir chamber 502 to transfer slurry to the analysis unit 140 may also be used to recirculate a portion of the sample slurry via recirculation line 120a along with adding water to the recirculated slurry from an external water source (see, e.g., FIG. 9) as the means to adjust (i.e. decrease) the water/solids ratio of the sample slurry in stir chamber 502. [0097] The spectrometer 550 may also be used to identify other properties of the sample, including but not limited to soil structure (e.g., sand content), color profile, and organic matter content. By monitoring the reflectance of the sample at various levels of agitation, properties of fractions of the sample can also be measured (e.g., stop agitating the sample and let heavy particles settle downward onto the lens 551 of the spectrometer). [0098] Once the desired target mass ratio of water to solids for the slurry has been reached, the sample slurry is ready for chemical analysis. Stirring device 500 includes a vertically-extending filtrate suction tube 521 through which pump 120 (a slurry pump in one embodiment) can extract slurry from the internal cavity 530 of stir chamber 502 via one or more filtrate outlet ports 520. In one embodiment, plural outlet ports may be provided which are fluidly coupled to the vertical Attorney Docket No.23162/WO suction tube 521 via a branched flow manifold 521a as shown. The use of multiple smaller filtrate outlet ports allows several samples to be drawn simultaneously from stir chamber 502 for different portions of the analysis unit to test for different analytes at the same time in parallel. In other embodiments, a single larger filtrate outlet port may be used instead. The filtrate outlet ports 520 may be disposed in the upper housing section 511 of the stirring device and may extend laterally through the upper housing section (see, e.g., FIGS.22-23) as shown. The filtrate suction tube 521 is suspended from the upper housing section 511 such that the weight of the tube is preferably supported solely by the upper housing section alone. This support configuration does not add to weight of the stir chamber when weighting the slurry via strain gauge 504, as described elsewhere herein. In other possible embodiments, the filtrate outlet ports 520 could instead be disposed in the sidewall of the lower housing section 512 (stir chamber 502) such that the filtrate suction tube 521 would then be supported by the stir chamber and its weight taken into account when weighing the slurry. [0099] There may be particles in the sample slurry however that are too large in size to be tolerated by the small openings and flow conduits within the analysis unit 140. This could cause issues such as plugging/blockages in the downstream analysis equipment. Accordingly, a combination of filtration and separation features/measures may be implemented in stir chamber 502 to prevent the largest particles (solids) which could cause problems from leaving the chamber and entering the analysis equipment. [0100] In one embodiment, the filtration feature may comprise a slurry secondary filter 522 (grinder 110 acting as the primary filter for large particle separation). Filter 522 is disposed upstream of pump 120 in the slurry flow circuit shown in FIG. 9. In one embodiment, the filter 522 may be disposed inside stir chamber 502, and may be coupled to the filtrate suction tube 521 inside the internal cavity 530 of the stir chamber. For example, filter 522 may be coupled to the bottom inlet end of suction tube 521 which hangs down from above into stir chamber internal cavity 530 and is suspended above the bottom of the cavity (see, e.g., FIG. 22). In one embodiment, filter 522 may be a mesh filter comprising a mesh screen having a plurality of mesh openings sized to prevent solid particles exceeding a predetermined maximum size from being drawn into the filtrate suction tube 521 and passing downstream. Accordingly, the size of the screen openings of such a filter are sized in proportion to the smallest flow passage of the analysis Attorney Docket No.23162/WO equipment of analysis unit 140 to not pass particles exceeding the smallest flow passage size (e.g., diameter). [0101] The separation feature comprises limiting the rotational speed of the agitator 250 so that the heaviest (largest) particles in the sample slurry are not lifted high enough in the slurry column to be drawn toward and onto the secondary filter 522, which is located and suspended by a vertical distance above the floor or bottom of the stir chamber in internal cavity 530. This could otherwise result in frequent plugging of the small mesh screen openings of the filter. Agitation is still necessary to promote chemical homogeneity in the sample, but limited to agitate the slurry gently enough to therefore leave large and chemically irrelevant particles below the secondary filter at the bottom of the stir chamber. Accordingly, agitator 250 has a maximum rotational speed selected to keep sample solids large particles at the bottom of the stir chamber 502, which prevents the large particles from being drawn to the secondary filter 522. In other words, the agitator is configured and operable to stir the slurry via the blade 253 at a maximum speed selected so that at least some larger particles drop out of suspension from the slurry and collect at a bottom of the internal cavity 530 of the stir chamber. [0102] To further help keep the slurry solids particles from being drawn onto filter 522, the bottom or floor 530a of stir chamber internal cavity 530 may be sloped from side to side such that the portion of the floor beneath the filter may be lower than the portion of the floor beneath the agitator blade 253 (see, e.g., FIG. 21). This deeper portion of stir chamber internal cavity 530 beneath the filtrate suction tube 521 and filter 522 forms a recess or pocket in which larger particles can settle out of suspension and collect without being drawn upwards towards the filter 522. In addition, waste port 543 may be coupled to this deeper portion of the stir chamber internal cavity 530 beneath the filter 522 to more effectively flush residual solids out with water between slurry processing runs. Accordingly, the sloped floor 530a of stir chamber 502 provides multiple functions and benefits. [0103] In some embodiments, a vacuum sensor 523 may be disposed upstream of pump 120 between secondary filter 522 and the pump to allow for the detection of a clogged secondary filter screen. In one embodiment, vacuum sensor 523 may be fluidly coupled to and disposed on the filtrate suction tube 521 on the downstream filtrate side of secondary filter 522. The vacuum sensor may be operable coupled to programmable controller 300 to provide automatic detection of a plugged/clogged filter 522 by the controller. The controller may then terminate slurry extraction Attorney Docket No.23162/WO from stir chamber 502 by stopping operation of pump 120 until the clogged filter can be cleaned. In other embodiments, vacuum sensor 523 may be fluidly coupled to the flow conduit 120b between pump 120 and stir chamber 502 (reference FIG. 9). [0104] In alternative embodiments, pump 120 may be omitted altogether and the slurry filtrate may flow via gravity from stir chamber 502 to analysis unit 140 for processing and analysis for various analytes or other relevant properties of the agricultural sample. [0105] As discussed above, a stirring device may include a filter, such as (but not limited to) filter 522 of Fig. 22 to prevent solid particles exceeding a predetermined size from being passed downstream. With regular use, however, such filters may become clogged by particles. [0106] Figs. 25-35 disclose two exemplary systems, and a corresponding method, for cleaning such a filter of a stirring device, or another type of filter or other device. Figs.25-29 discuss a first embodiment of such a system. This first embodiment builds on the system 520 of Figs. 9-24 for processing an agricultural slurry received from a source (such as grinder 110), though the invention may be applied to different systems for processing an agricultural slurry. Specifically, the first embodiment adds an ultrasonic transducer 560 to the system of Figs.9-24 to clean filter 522 of the stirring device 500, the filter 522 being fluidly coupled to outlet ports 520 and being positioned inside the internal cavity 530 of the stir chamber 502 to filter the slurry. [0107] As discussed with respect to Figs.9-24, the system may include a stir chamber 502, the stir chamber 502 having a housing 510 defining an internal cavity 530 configured to receive an agricultural sample slurry. The exemplified stir chamber 502 further includes a vertically- extending filtrate suction tube 521 through which pump 120 (a slurry pump in one embodiment) can extract slurry from the internal cavity 530 of stir chamber 502 via one or more filtrate outlet ports 520. This embodiment further includes a filter 522 upstream of pump 120 in the slurry flow circuit shown in FIG.9. As discussed in further detail above, the filter 522 may be disposed inside stir chamber 502, and may be coupled to the filtrate suction tube 521 inside the internal cavity 530 of the stir chamber 502. The filter 522 may be a mesh filter comprising a mesh screen having a plurality of mesh openings sized to prevent solid particles exceeding a predetermined maximum size from being drawn into the filtrate suction tube 521 and passing downstream. It is noted that the filter 522 would typically have a finer screen for blocking smaller particles than the screen shown in Figs. 25-29, but such a finer screen is not illustrated. It is further noted that, in other embodiments, other types and shapes of filters may be used. For example, the invention may be Attorney Docket No.23162/WO used for cleaning a filter attached to the stir chamber, as opposed to a filter hanging in the stir chamber, and the filtrate line outlet ports may come out of the side of the chamber. It is further noted that the invention is not limited to a stir chamber using a filtrate suction tube, and may apply to a variety of filters. [0108] The ultrasonic transducer 560 may be mounted to the housing 510 of the stir chamber 502. This is best shown by Fig. 26. (Note that for ease of viewing Fig. 25 omits the housing 510.) In the exemplified embodiment, the ultrasonic transducer 560 is mounted to an outer wall 510A of the housing 510 of the stir chamber 502, though the invention is not so limited. The exemplified ultrasonic transducer 560 is mounted such that a front portion 561A of the front driver element 561 passes through the housing 510 of the stir chamber 502 such that it may be positioned proximate to or in physical contact with the filter 522. The front portion 561A of the front driver element 561 of the of the ultrasonic transducer 560 may comprise grooves 567 and O rings 564 configured to fit within the grooves 567 to seal liquid within the internal cavity 530 of the stir chamber 502. In other embodiments, other means of sealing liquid within the internal cavity 530 may be utilized. [0109] In the exemplified embodiment, the ultrasonic transducer 560 is positioned proximate to the filter 522. In certain embodiments, the distance D between the ultrasonic transducer 560 and the filter 522 is 2 inches or less. Generally, the smaller the distance D, the more effective the ultrasonic cleaning is. The required proximity for effective cleaning will depend on transducer power and the required pressure for a particular cleaning task. Where the ultrasonic transducer 560 does not touch the filter, the filter 522, along with the other components of the stir chamber 502, may be kept mechanically isolated from other portions of the stirring device 500. In such an embodiment, the ultrasonic transducer 560 may be physically coupled to the lower housing 512 of the stir chamber 502, while the filter 522 is not physically coupled to the stir chamber 502. [0110] The ultrasonic transducer 560 may be configured to cause cavitation bubbles to form when the ultrasonic transducer 560 is activated and the filter is immersed in a liquid. In the exemplified embodiment, the ultrasonic transducer 560, when activated, vibrates along a first axis A perpendicular to the outer wall 510A of the housing 510 of the stir chamber 502. The mechanical oscillation transfers to the liquid, causing bubbles to form and burst. Each burst creates a localized area of high pressure that may be thousands of psi. The frequency used for ultrasonic cleaning is typically 10-100 KHz and any frequency in this range may be used, as well as other frequencies. Attorney Docket No.23162/WO In one embodiment, 28 KHz is used, which is low in the range but avoids the auditory spectrum. In other embodiments, other frequencies towards the bottom end of the 10-100 KHz spectrum are used. In certain embodiments, a lower frequency is preferred, as lower frequencies create larger cavitation bubbles having more energy per bubble. Higher frequencies, by contrast, create more cavitation bubbles but with lower energy per bubble. It is noted that the liquid in which cavitation bubbles are formed could include or omit a cleaning solution. It is further noted that, in alternative embodiments, cleaning may be performed without using cavitation bubbles. For example, physical vibration (ultrasonic or otherwise) may be used to perform cleaning. [0111] The ultrasonic transducer 560 is designed to focus energy where it is most needed for cleaning the filter 522. In the exemplified embodiment of Figs. 25-29, the ultrasonic transducer 560 has a front end 560A and a back end 560B. The ultrasonic transducer 560 includes a front driver element 561, a back driver element 562, two piezoelectric elements 563 positioned between the front driver element 561 and the back driver element 562, a bolt 569 configured to pass through at least a portion of each of the front driver element 561, the back driver element 562, and the two piezoelectric elements 563. The ultrasonic transducer 560 further includes an insulation sleeve 565 surrounding a portion of the bolt 569 to prevent the bolt 569 from physically contacting the two piezoelectric elements 563. The insulation sleeve 565 comprises a dielectric material. In the exemplified embodiment, the two piezoelectric elements comprise a conductive piezoelectric ceramic material. [0112] The front driver element 561 (sometimes referred to as the horn) has a front portion 561A proximate to the front end 560A of the ultrasonic transducer 560 and an opposite rear portion 561B. A cross sectional area A1 of the front portion 561A of the front driver element 561 is smaller than a cross sectional area A2 of the rear portion 561B of the front driver 561 , where each of the cross sectional areas A1, A2 is perpendicular to the first axis. [0113] In the exemplified embodiment, the front portion 561A of the front driver 561 is shaped as a first cylinder, and the rear portion 561B of the front driver 561 is shaped as a second cylinder distinct from the first cylinder, the first cylinder 561A having a circular cross section whose area A1 is less than an area A2 of a circular cross section of the second cylinder 561B. Note, however, that the invention is not limited to these cylinder shapes, as is shown in the second embodiment discussed below. Attorney Docket No.23162/WO [0114] By reducing the cross sectional area of the front driver 561, the smaller front portion 561A vibrates more than the larger rear portion 561B. This design helps to focus the energy upon the filter, thus helping ensure that most cavitation bubbles are formed on or near the filter 522, thus improving the quality of the ultrasonic cleaning upon the filter 522. Fig. 27 shows that the front portion 561A of the front driver element 561 has an area A1 that is large enough to envelop the bottom portion of the filter 522, but not larger. Focusing on the bottom of the filter 522 may be preferred in circumstances where the bottom is the portion of the filter 522 most likely to be clogged. [0115] In certain embodiments, the front driver 561 may comprise aluminum and the back driver element 562 may comprise stainless steel. Further, the mass of the front driver element 561 may be plus or minus 5% of the mass of the back driver element 562. Further, the back driver element 562 may have a higher density than the front driver element 561. The invention, however, is not so limited to any of these particular exemplary features. [0116] The exemplified ultrasonic transducer 560 further includes a housing 566 surrounding a portion of the front driver 561, the back driver 562, the two piezoelectric elements 563, and the bolt 569. The housing 566 of the ultrasonic transducer 560 may further include a mounting bracket 568 configured to mount the ultrasonic transducer 560 to a housing 510 of a stir chamber 502. As shown, the housing 566 includes a apertures 568B through which a screw 568A or other securing element may pass to secure the ultrasonic transducer 560 to the housing 510. Note that the mounting bracket 568 may further function as a cap to the housing 566 of the ultrasonic transducer 560. [0117] Figs. 30-34 disclose a second embodiment of a system for cleaning a filter of a stirring device. This second embodiment bears many similarities to the first embodiment shown in Figs. 25-29, and as such many of the same reference numbers are used to represent the same or substantially similar components and features, and the description of those similar components and feature are not repeated here. Rather, the discussion below is limited to the substantial differences between the first and second embodiments. [0118] The primary difference between the embodiments is that the ultrasonic transducer 560-2 of the second embodiment has a front driver element 561-1 that is shaped differently from the front driver element 561 of the first embodiment. Specifically, the front portion 561A-2 of the front driver element 561-2 has a rectangular cross section rather than a circular cross section. As shown Attorney Docket No.23162/WO most clearly in Fig. 32, this allows the cross sectional area A1-2 of the front portion 561A-2 to more closely match the shape of the filter 522. Note that, in this embodiment, the cross sectional area A2-2 of the rear portion 561B-2 of the front driver element 561-2 is still circular and is still larger than the cross sectional area A1-2 of the front portion 561A-2. Finally, it is noted that alternative groove 567-2 and O ring 564-2 to seal liquid within the internal cavity 530 may be used. [0119] Fig.35 displays a method for cleaning a filter of a stirring device for an agricultural sample slurry. The method includes the following operations: positioning an ultrasonic transducer proximate to or in physical contact with the filter of the stirring device (operation 591); stirring an agricultural sample slurry in a stirring device, the stirring device comprising a filter (operation 592); immersing the filter of the stirring device in a liquid (operation 593); and activating the ultrasonic transducer to cause cavitation bubbles to form in the liquid and thereby clean the filter (operation 594). The operations need not be performed in this order. Operations 592-594 may be repeated such that the ultrasonic cleaning may be carried out after each new slurry is passed through. Note also that the method may also include a sensor for sensing clogs and thereby triggering a cleaning of the filter. As discussed above, in other embodiments, the cleaning method may be based on the ultrasonic transducer causing the filter to physically vibrate, rather than the creation of cavitation bubbles. Further, while in some embodiments, cleaning occurs after the filter is done processing a slurry, in other embodiments, the cleaning caused by the ultrasonic transducer may be carried out while the filter is actively processing a slurry. [0120] The disclosed system and method of cleaning a filter of a stir chamber provides several advantages. For example, they enable the high pressure cleaning of a filter without the need to deconstruct the stir chamber or provide physical access to the filter. While the filter may alternatively be cleaned using high pressure water, such an approach requires a flow of liquid. The ultrasonic cleaning system and method described herein enable high-pressure cleaning without the need for a flow of liquid. [0121] The system for analyzing an agricultural sample disclosed herein is usable with and may form part of an overall agricultural sampling and analysis systems, such as but not limited to those described in U.S. Patent Application Publication Nos. 2018/0124992A1, US20210123836A1, US20210123936A1, US20210131917A1, US20210131929A1, US20210208035A1, US20210208036A1, US20210208037A1, US20210208123A1, US20210268456A1, Attorney Docket No.23162/WO US20210285869A1, US20210341442A1, US20210341452A1, US20220196628A1, US20230133335A1, US20230144670A1, US20230151810A1, US20230173415A1, US20230243792A1, US20230243801A1, US20230243802A1, US20230243804A1, US20230266289A1, US20230266290A1, US20230273130A1, US20230273171A1, US20230273172A1, US20230273173A1, US20230304987A1, US20230417363A1, US20230417635A1, US20240189743A1, US20240189744A1, US20240192112A1, US20240192708A1, US20240198331A1, US20240200547A1, PCT Publication Nos. WO2021/171120, WO2021/171121, WO2022/243792, WO2022/243797, WO2022/243806, WO2022/243807, WO2022/243809, WO2022/259071, WO2022/259073, WO2022/259074, WO2023/031725, WO2023/031726, WO2023/031727, WO2023/042032, WO2023/042033, WO2023/042035, WO2023/042036, WO2023/042037, WO2023/042038, WO2023/042039, WO2023/161727, WO2023/161728, WO2023/170480, WO2023/170482, WO2023/227959, WO2023/227960, WO2023/248015, WO2023/248016, WO2024/023728, WO2024/023729, WO2024/023730, and WO2024/023731, PCT Application Nos. PCT/IB2024/051283, filed 12- Feb-2024 and PCT/IB2024/051820, filed 26-Feb-2024, U.S. Application Nos. 63/551120, filed 08-Feb-2024, 63/552730, filed 13-Feb-2024, 63/552739, filed 13-Feb-2024, 63/559305, filed 29- Feb-2024, 63/559308, filed 29-Feb-2024, 63/559312, filed 29-Feb-2024, 63/559316, filed 29-Feb- 2024, 63/586486, filed 29-Sep-2023, 63/586489, filed 29-Sep-2023, 63/586497, filed 29-Sep- 2023, 63/586500, filed 29-Sep-2023, 63/586504, filed 29-Sep-2023, 63/586510, filed 29-Sep- 2023, 63/586514, filed 29-Sep-2023, 63/586524, filed 11-Oct-2023, 63/586529, filed 29-Sep- 2023, 63/586545, filed 29-Sep-2023, 63/586551, filed 29-Sep-2023, 63/586555, filed 29-Sep- 2023, 63/586562, filed 29-Sep-2023, 63/586608, filed 29-Sep-2023, 63/586619, filed 29-Sep- 2023, 63/586630, filed 29-Sep-2023, 63/586638, filed 29-Sep-2023, 63/586656, filed 29-Sep- 2023, 63/586672, filed 29-Sep-2023, 63/586702, filed 29-Sep-2023, 63/586726, filed 29-Sep- 2023, 63/586955, filed 29-Sep-2023, 63/586966, filed 29-Sep-2023, 63/586978, filed 29-Sep- 2023, 63/586984, filed 29-Sep-2023, 63/586990, filed 29-Sep-2023, and 63/646070, filed 13-May- 2024. EXAMPLES [0122] The following are nonlimiting examples. [0123] Example 1 - a system for processing an agricultural slurry, the system comprising: a source of an agricultural sample slurry; a stirring device comprising: a stir chamber comprising: Attorney Docket No.23162/WO a housing defining an internal cavity configured to receive an agricultural sample slurry; one or more outlet ports configured to release slurry from the internal cavity; and a filter fluidly coupled to the one or more outlet ports and positioned inside the internal cavity of the stir chamber to filter the slurry; and an ultrasonic transducer positioned proximate to or in physical contact with the filter. [0124] Example 2 - the system according to Example 1 wherein the ultrasonic transducer is configured to cause cavitation bubbles to form when the ultrasonic transducer is activated and the filter is immersed in a liquid. [0125] Example 3 - the system according to Example 1 wherein the stir chamber further comprises a filtrate suction tube configured to extract slurry from the internal cavity through the one or more outlet ports. [0126] Example 4 - the system according to Example 1 wherein the ultrasonic transducer is mounted to a wall of the housing of the stir chamber. [0127] Example 5 - the system according to any one of the preceding Examples wherein there is a distance between the ultrasonic filter and the filter such that the ultrasonic filter and the filter are not in physical contact. [0128] Example 6 - the system according to any one of the preceding Examples wherein the ultrasonic transducer, when activated, vibrates along a first axis perpendicular to an outer wall of the housing of the stir chamber. [0129] Example 7 - the system according to any one of the preceding Examples: wherein the ultrasonic transducer comprises a front driver element at a front end of the ultrasonic transducer; wherein the front driver element has a front portion proximate to the front end of the ultrasonic transducer and an opposite rear portion; and wherein a cross sectional area of the front portion of the front driver element is smaller than a cross sectional area of the rear portion of the front driver, where each of the cross sectional areas is parallel to an outer wall of the housing of the stir chamber. [0130] Example 8 - the system according to Example 7 wherein the front portion of the front driver is shaped as a first cylinder and the rear portion of the front driver is shaped as a second cylinder distinct from the first cylinder, the first cylinder having a circular cross section whose circumference is less than a circumference of a circular cross section of the second cylinder. Attorney Docket No.23162/WO [0131] Example 9 - the system according to Example 7: wherein the front portion of the front driver element of the ultrasonic transducer comprises grooves; and wherein the ultrasonic transducer further comprises O rings configured to fit within the grooves of the front driver to seal liquid within the internal cavity of the stir chamber. [0132] Example 10 - the system according to any one of the preceding Examples wherein the ultrasonic transducer comprises: a front driver element; a back driver element; two piezoelectric elements positioned between the front driver element and the back driver element; a bolt configured to pass through at least a portion of each of the front driver element, the back driver element, and the two piezoelectric elements; and an insulation sleeve surrounding a portion of the bolt to prevent the bolt from contacting the two piezoelectric elements, the insulation sleeve comprising a dielectric material. [0133] Example 11 - the system according to Example 10 wherein the ultrasonic transducer further comprises a housing surrounding at least a portion of the front driver, the back driver, the two piezoelectric elements, and the bolt. [0134] Example 12 - the system according to Example 11 wherein the housing of the ultrasonic transducer further comprises a mounting bracket configured to mount the ultrasonic transducer to an outer wall of the housing of the stir chamber. [0135] Example 13 - the system according to Example 10 wherein the front driver comprises aluminum and the back driver comprises stainless steel. [0136] Example 14 - the system according to Example 10 wherein a mass of the front driver element is plus or minus 5% of a mass of the rear driver element. [0137] Example 15 - the system according to Example 10 wherein the back driver element has a higher density than the front driver element. [0138] Example 16 - the system according to Example 10 wherein each of the two piezoelectric elements comprise a conductive piezoelectric ceramic material. [0139] Example 17 - the system according to any one of the preceding Examples wherein the source of the a agricultural slurry sample comprises a grinder. [0140] Example 18 - the system according to Example 3 wherein the filter comprises a mesh screen having openings sized to prevent sold particles exceeding a maximum size from being drawn into the filtrate suction tube. Attorney Docket No.23162/WO [0141] Example 19 - the system according to Example 18 wherein the stirring device further comprises a vacuum sensor disposed upstream of the pump between the pump and the filter, the vacuum sensor operable to detect a vacuum condition which is indicative of a clogged condition of the filter. [0142] Example 20 - the system according to Example 3: wherein the housing of the stir chamber comprises an upper housing section and a lower housing section; and wherein the one or more filtrate outlet ports are disposed in the upper housing section of the stirring device, and the filtrate suction tube is suspended in the internal cavity of the stir chamber from the upper housing section. [0143] Example 21 - the system according to Example 20 wherein the filtrate suction tube extends vertically from at least a top end of the stir chamber down into a lower portion of the internal cavity of the stir chamber. [0144] Example 22 - the system according to Example 21 wherein the filtrate suction tube is fluidly coupled to a pump via the filtrate outlet ports, the pump operable to apply suction to the filtrate suction tube for extracting the slurry from the stir chamber. [0145] Example 23 - the system according to Example 22 wherein at least a portion of the extracted slurry is transferred to an analysis unit. [0146] Example 24 - the system according to any one of the preceding Examples wherein the stirring device further comprises a strain gauge structurally coupled to the stir chamber, the strain gauge configured and operable to measure a weight of the stir chamber with and without slurry. [0147] Example 25 - the system according to Example 24 wherein the strain gauge independently supports the stir chamber, the stir chamber being mechanically isolated from other portions of the stirring device. [0148] Example 26 - the system according to any one of the preceding Examples wherein the stirring device further comprises an agitator including a rotatable agitator shaft with blade disposed in the internal cavity of the stir chamber and a motor operably coupled to the agitator shaft. [0149] Example 27 - an ultrasonic transducer for causing cavitation bubbles to form in a liquid, the ultrasonic transducer comprising: a front driver element; a back driver element; two piezoelectric elements positioned between the front driver element and the back driver element; a bolt configured to pass through at least a portion of each of the front driver element, the back Attorney Docket No.23162/WO driver element, and the two piezoelectric elements; and an insulation sleeve surrounding a portion of the bolt to prevent the bolt from contacting the two piezoelectric elements, the insulation sleeve comprising a dielectric material; wherein the ultrasonic transducer vibrates along a first axis; wherein the front driver element has a front portion proximate to the front end of the ultrasonic transducer and an opposite rear portion; and wherein a cross sectional area of the front portion of the front driver element is smaller than a cross sectional area of the rear portion of the front driver, where each of the cross sectional areas is perpendicular to the first axis. [0150] Example 28 - the ultrasonic transducer according to Example 27 wherein the front portion of the front driver is shaped as a first cylinder and the rear portion of the front driver is shaped as a second cylinder distinct from the first cylinder, the first cylinder having a circular cross section whose circumference is less than a circumference of a circular cross section of the second cylinder. [0151] Example 29 - the ultrasonic transducer according to any one of Examples 27-28 wherein the ultrasonic transducer further comprises a housing surrounding at least a portion of the front driver, the back driver, the two piezoelectric elements, and the bolt. [0152] Example 30 - the ultrasonic transducer according to Example 29 wherein the housing of the ultrasonic transducer comprises a mounting bracket configured to mount the ultrasonic transducer to an outer wall of a housing of a stir chamber. [0153] Example 31 - the ultrasonic transducer according to any one of Examples 27-30 wherein the front driver element comprises aluminum and the back driver element comprises stainless steel. [0154] Example 32 - the ultrasonic transducer according to any one of Examples 27-31 wherein a mass of the front driver element is plus or minus 5% of a mass of the back driver element. [0155] Example 33 - the ultrasonic transducer according to any one of Examples 27-32 wherein the back driver element has a higher density than the front driver element. [0156] Example 34 - the ultrasonic transducer according to any one of Examples 27-33 wherein each of the two piezoelectric elements comprise a conductive piezoelectric ceramic material. [0157] Example 35 - a method for cleaning a filter of a stirring device for an agricultural sample slurry, the method comprising: positioning an ultrasonic transducer proximate to or in physical contact with the filter of the stirring device; stirring an agricultural sample slurry in a stirring Attorney Docket No.23162/WO device, the stirring device comprising a filter; and activating the ultrasonic transducer to clean the filter. [0158] Example 36- the method of Example 35 further comprising immersing the filter of the stirring device in a liquid, wherein the activation of the ultrasonic transducer causes cavitation bubbles to form in the liquid and thereby clean the filter. [0159] Example 37 - the method of Example 36: wherein the filter is positioned in a stir chamber of the stirring device, the stir chamber comprising: a housing defining an internal cavity configured to receive the agricultural sample slurry; and a filtrate suction tube configured to extract slurry from the internal cavity through one or more filtrate outlet ports of the stirring device; wherein the filter is fluidly coupled to the filtrate suction tube and positioned inside the internal cavity of the stir chamber to filter the slurry. [0160] While the foregoing description and drawings represent some example systems, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that embodiments of the present disclosure may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods/processes described herein may be made. One skilled in the art will further appreciate that the embodiments of the present disclosure may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the embodiments of the present disclosure, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present embodiments of the present disclosure. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the embodiments of the present disclosure being defined by the appended claims and equivalents thereof, and not limited to the foregoing description or embodiments. Rather, the appended claims should be construed broadly, to include other variants and embodiments, which may be made by those skilled in the art without departing from the scope and range of equivalents of the embodiments of the present disclosure.

Claims

Attorney Docket No.23162/WO CLAIMS What is claimed is: 1. A system for processing an agricultural slurry, the system comprising: a source of an agricultural sample slurry; a stirring device comprising: a stir chamber comprising: a housing defining an internal cavity configured to receive an agricultural sample slurry; one or more outlet ports configured to release slurry from the internal cavity; and a filter fluidly coupled to the one or more outlet ports and positioned inside the internal cavity of the stir chamber to filter the slurry; and an ultrasonic transducer positioned proximate to or in physical contact with the filter. 2. The system according to claim 1 wherein the ultrasonic transducer is configured to cause cavitation bubbles to form when the ultrasonic transducer is activated and the filter is immersed in a liquid. 3. The system according to claim 1 wherein the stir chamber further comprises a filtrate suction tube configured to extract slurry from the internal cavity through the one or more outlet ports. 4. The system according to claim 1 wherein the ultrasonic transducer is mounted to a wall of the housing of the stir chamber. 5. The system according to any one of the preceding claims wherein there is a distance between the ultrasonic filter and the filter such that the ultrasonic filter and the filter are not in physical contact. 6. The system according to any one of the preceding claims wherein the ultrasonic transducer, when activated, vibrates along a first axis perpendicular to an outer wall of the housing of the stir chamber. 7. The system according to any one of the preceding claims: Attorney Docket No.23162/WO wherein the ultrasonic transducer comprises a front driver element at a front end of the ultrasonic transducer; wherein the front driver element has a front portion proximate to the front end of the ultrasonic transducer and an opposite rear portion; and wherein a cross sectional area of the front portion of the front driver element is smaller than a cross sectional area of the rear portion of the front driver, where each of the cross sectional areas is parallel to an outer wall of the housing of the stir chamber. 8. The system according to claim 7 wherein the front portion of the front driver is shaped as a first cylinder and the rear portion of the front driver is shaped as a second cylinder distinct from the first cylinder, the first cylinder having a circular cross section whose circumference is less than a circumference of a circular cross section of the second cylinder. 9. The system according to claim 7: wherein the front portion of the front driver element of the ultrasonic transducer comprises grooves; and wherein the ultrasonic transducer further comprises O rings configured to fit within the grooves of the front driver to seal liquid within the internal cavity of the stir chamber. 10. The system according to any one of the preceding claims wherein the ultrasonic transducer comprises: a front driver element; a back driver element; two piezoelectric elements positioned between the front driver element and the back driver element; a bolt configured to pass through at least a portion of each of the front driver element, the back driver element, and the two piezoelectric elements; and an insulation sleeve surrounding a portion of the bolt to prevent the bolt from contacting the two piezoelectric elements, the insulation sleeve comprising a dielectric material. 11. The system according to claim 10 wherein the ultrasonic transducer further comprises a housing surrounding at least a portion of the front driver, the back driver, the two piezoelectric elements, and the bolt. Attorney Docket No.23162/WO 12. The system according to claim 11 wherein the housing of the ultrasonic transducer further comprises a mounting bracket configured to mount the ultrasonic transducer to an outer wall of the housing of the stir chamber. 13. The system according to claim 10 wherein the front driver comprises aluminum and the back driver comprises stainless steel. 14. The system according to claim 10 wherein a mass of the front driver element is plus or minus 5% of a mass of the rear driver element. 15. The system according to claim 10 wherein the back driver element has a higher density than the front driver element. 16. The system according to claim 10 wherein each of the two piezoelectric elements comprise a conductive piezoelectric ceramic material. 17. The system according to any one of the preceding claims wherein the source of the a agricultural slurry sample comprises a grinder. 18. The system according to claim 3 wherein the filter comprises a mesh screen having openings sized to prevent sold particles exceeding a maximum size from being drawn into the filtrate suction tube. 19. The system according to claim 18 wherein the stirring device further comprises a vacuum sensor disposed upstream of the pump between the pump and the filter, the vacuum sensor operable to detect a vacuum condition which is indicative of a clogged condition of the filter. 20. The system according to claim 3: wherein the housing of the stir chamber comprises an upper housing section and a lower housing section; and wherein the one or more filtrate outlet ports are disposed in the upper housing section of the stirring device, and the filtrate suction tube is suspended in the internal cavity of the stir chamber from the upper housing section. 21. The system according to claim 20 wherein the filtrate suction tube extends vertically from at least a top end of the stir chamber down into a lower portion of the internal cavity of the stir chamber. Attorney Docket No.23162/WO 22. The system according to claim 21 wherein the filtrate suction tube is fluidly coupled to a pump via the filtrate outlet ports, the pump operable to apply suction to the filtrate suction tube for extracting the slurry from the stir chamber. 23. The system according to claim 22 wherein at least a portion of the extracted slurry is transferred to an analysis unit. 24. The system according to any one of the preceding claims wherein the stirring device further comprises a strain gauge structurally coupled to the stir chamber, the strain gauge configured and operable to measure a weight of the stir chamber with and without slurry. 25. The system according to claim 24 wherein the strain gauge independently supports the stir chamber, the stir chamber being mechanically isolated from other portions of the stirring device. 26. The system according to any one of the preceding claims wherein the stirring device further comprises an agitator including a rotatable agitator shaft with blade disposed in the internal cavity of the stir chamber and a motor operably coupled to the agitator shaft. 27. An ultrasonic transducer for causing cavitation bubbles to form in a liquid, the ultrasonic transducer comprising: a front driver element; a back driver element; two piezoelectric elements positioned between the front driver element and the back driver element; a bolt configured to pass through at least a portion of each of the front driver element, the back driver element, and the two piezoelectric elements; and an insulation sleeve surrounding a portion of the bolt to prevent the bolt from contacting the two piezoelectric elements, the insulation sleeve comprising a dielectric material; wherein the ultrasonic transducer vibrates along a first axis; wherein the front driver element has a front portion proximate to the front end of the ultrasonic transducer and an opposite rear portion; and wherein a cross sectional area of the front portion of the front driver element is smaller than a cross sectional area of the rear portion of the front driver, where each of the cross sectional areas is perpendicular to the first axis. Attorney Docket No.23162/WO 28. The ultrasonic transducer according to claim 27 wherein the front portion of the front driver is shaped as a first cylinder and the rear portion of the front driver is shaped as a second cylinder distinct from the first cylinder, the first cylinder having a circular cross section whose circumference is less than a circumference of a circular cross section of the second cylinder. 29. The ultrasonic transducer according to any one of claims 27-28 wherein the ultrasonic transducer further comprises a housing surrounding at least a portion of the front driver, the back driver, the two piezoelectric elements, and the bolt. 30. The ultrasonic transducer according to claim 29 wherein the housing of the ultrasonic transducer comprises a mounting bracket configured to mount the ultrasonic transducer to an outer wall of a housing of a stir chamber. 31. The ultrasonic transducer according to any one of claims 27-30 wherein the front driver element comprises aluminum and the back driver element comprises stainless steel. 32. The ultrasonic transducer according to any one of claims 27-31 wherein a mass of the front driver element is plus or minus 5% of a mass of the back driver element. 33. The ultrasonic transducer according to any one of claims 27-32 wherein the back driver element has a higher density than the front driver element. 34. The ultrasonic transducer according to any one of claims 27-33 wherein each of the two piezoelectric elements comprise a conductive piezoelectric ceramic material. 35. A method for cleaning a filter of a stirring device for an agricultural sample slurry, the method comprising: positioning an ultrasonic transducer proximate to or in physical contact with the filter of the stirring device; stirring an agricultural sample slurry in a stirring device, the stirring device comprising a filter; and activating the ultrasonic transducer to clean the filter. 36. The method of claim 35 further comprising immersing the filter of the stirring device in a liquid, wherein the activation of the ultrasonic transducer causes cavitation bubbles to form in the liquid and thereby clean the filter. 37. The method of claim 36, wherein the filter is positioned in a stir chamber of the stirring device, the stir chamber comprising: a housing defining an internal cavity configured to receive the agricultural sample slurry; Attorney Docket No.23162/WO and a filtrate suction tube configured to extract slurry from the internal cavity through one or more filtrate outlet ports of the stirring device; wherein the filter is fluidly coupled to the filtrate suction tube and positioned inside the internal cavity of the stir chamber to filter the slurry.