CN111108835B - Method for improving low organic soil - Google Patents

Abstract

The invention discloses a method for improving low organic soil, and belongs to the technical field of soil improvement. The method comprises the following steps: mixing low organic soil with organic content less than 1% and biochemical oxygen demand: the leachate of the domestic garbage landfill with the chemical oxygen demand less than 0.1 is prepared from the following components in percentage by mass (2.5-5.3): 1, paving and placing the mixed soil under an aerobic condition, and continuously replenishing percolate into the mixed soil along with the reduction of water in the mixed soil so as to keep the water content in the mixed soil unchanged all the time until the organic matter content of the organic matter soil in the mixed soil is more than 3 percent. The method stably combines the household garbage landfill leachate and the low organic soil under an aerobic condition, is simple and convenient to operate, can realize the resource utilization of the household garbage landfill leachate, reduce the cost for improving the low organic soil and the treatment capacity of the garbage leachate, can improve the water and fertilizer retention capacity and the nutrient content of the low organic soil, and realize the effective improvement of the low organic soil.

Description

A kind of low organic matter soil improvement method

technical field

The invention specifically relates to a low organic matter soil improvement method, which belongs to the technical field of soil improvement.

Background technique

Soil improvement requires the use of pedology, ecology and other multidisciplinary theoretical techniques to improve soil properties, improve soil fertility, and create a good soil environment. Soil improvement mainly includes barren soil improvement, saline-alkali land improvement, acidified soil improvement, and soil structure improvement. Among them, barren soil, that is, low organic matter soil, is widely distributed in the northwest of my country, and has the characteristics of low viscosity, weak ability to retain water and fertilizer, and low nutrient content. The improvement of low organic matter soil is an extremely important part of soil improvement in my country.

Soil organic matter can not only provide nutrients for plant growth, increase the effectiveness of nutrients, retain water, fertilizer and enhance the buffer capacity of soil to acid and alkali, but also promote the formation of soil aggregate structure and improve soil physical properties. At present, the improvement methods for low organic matter soil are as follows: 1) A large amount of organic fertilizer is applied, and the applied organic fertilizer is easy to form humus, thereby promoting the formation of agglomerate structure and the improvement of organic matter; 2) Foreign soil, using non-local native High organic matter soil, such as river mud and pond mud to improve low organic matter soil; 3) Use agricultural biological measures, including land leveling, soil fertilization, planting economic crops or green manure; 4) For low organic matter soil with thin sand layer, use late autumn Press sand to mix the bottom clay with the surface sand to increase its organic matter content; 5) Use chemical reagents such as soil conditioners for improvement.

The above-mentioned improvement methods for low-organic soil usually require relatively complex improvement measures and improvement agents, and at the same time require a lot of capital and time investment. Therefore, it is necessary to develop an easy-to-operate and low-cost method to effectively improve low-organic soils.

SUMMARY OF THE INVENTION

In view of the problems in the prior art, the present invention provides a low-organic soil improvement method. The method utilizes the stable combination of domestic waste landfill leachate and low-organic soil under aerobic conditions, which are stably stored in a storage tank. It is simple and convenient, not only can realize the resource utilization of domestic waste landfill leachate, reduce the cost of improving low-organic soil and the amount of landfill leachate, but also improve the water and fertilizer retention capacity and nutrients (organic and nitrogen) of low-organic soil. ) content to achieve effective improvement of low organic matter soils.

For realizing the above technical purpose, the technical scheme of the present invention is:

A low-organic soil improvement method, the steps are: combining low-organic soil with an organic matter content of less than 1% and a domestic waste landfill leachate with a biochemical oxygen demand: chemical oxygen demand B/C less than 0.1 according to the mass ratio of ( 2.5 ~ 5.3): 1 Mixing, the mixed soil is paved under aerobic conditions, and the leachate is continuously added to the mixed soil as the water in the mixed soil decreases, so as to keep the water content in the mixed soil unchanged until Terminate when the organic matter content of the organic matter soil in the mixed soil is greater than 3%.

Preferably, the domestic waste landfill leachate is stored or treated in a storage tank to reach a stable state.

Preferably, the characteristics of the leachate are: pH 7.5-8.3; alkalinity 7000-9000 mgCaCO ₃ /L; COD _Cr 4000-6500 mg/L; BOD ₅ 120-200 mg/L, biochemical oxygen demand: chemical oxygen demand less than 0.1; the characteristics of the low-organic soil are: bulk density 1.0-1.7 g/cm ³ , field water holding capacity less than 25%, pH 7.5-8.5, and organic matter content less than 1%.

Preferably, the aerobic condition means that the soil after mixing is spread and placed in the air at room temperature, with a thickness of no more than 0.5 m, and the soil is turned over and stirred every 3 days.

Preferably, the leachate is irrigated to the surface of the low-organic soil by means of irrigation to realize mixing with the low-organic soil.

Further preferably, the irrigation method can be furrow irrigation or drip irrigation.

As can be seen from the above description, the present invention has the following advantages:

1. The present invention mixes domestic waste landfill leachate with low-organic soil and spreads it under aerobic conditions, so that the organic matter and nitrogen in the leachate can be stably combined with the low-organic soil. Transfer to low organic matter soil can provide a better substrate environment for microorganisms in low organic matter soil, and in turn, microorganisms with good substrate environment can better promote the conversion of a large amount of ammonia nitrogen in leachate to nitrate nitrogen through nitrification. It can be used as nitrogen fertilizer to improve the water and fertilizer retention capacity and nutrient (organic matter and nitrogen) content of low-organic soil, and achieve effective improvement of low-organic soil.

2. The method of the present invention is easy to operate, can realize the resource utilization of the leachate of the domestic waste landfill, and reduce the cost of improving the low-organic soil and the disposal amount of the landfill leachate.

Description of drawings

Fig. 1 is the process schematic diagram of the inventive method;

Detailed ways

The features of the present invention are further described below through examples, but the claims of the present invention are not limited in any way.

In the following examples of the present invention, the low-organic soil is taken from loess in Northwest China; the leachate is taken from a landfill leachate adjustment and storage tank.

Example 1:

(1) Characteristics of low organic matter soil

The object of improvement in this example is barren soil with soil organic matter content below 1%, and typical features are: bulk density 1.0-1.2 g/cm ³ , moisture content 3-5%, pH 7.5-8.0, and organic matter content 0.5-0.75%.

(2) Characteristics of stable leachate

The leachate selected in this example is a domestic waste landfill leachate that has been stably stored in a storage tank, and its typical characteristics are: pH: 8.0-8.3; alkalinity: 8000-9000mgCaCO3/L; COD _Cr : 4000-4200mg /L; BOD ₅ : 120-150 mg/L, and B/C (biochemical oxygen demand: chemical oxygen demand) was 0.03.

(3) Composition ratio

In the present invention, the mass ratio of low-organic soil to leachate is required to be 2.5-5.3, that is, the soil moisture content after mixing is 16-28%, and the low-organic soil content is 72-84%. In this example, the mass ratio of low-organic soil to leachate is 5:1, and the moisture content of the mixed soil is 16.7%.

(4) Improvement method

The domestic waste landfill leachate of the above-mentioned characteristics is sprayed onto the surface of the low-organic soil with the above-mentioned characteristics to realize the mixing of the leachate and the low-organic soil, wherein, the mass ratio of the low-organic soil and the leachate mixed is 5:1 (i.e. mixed. The soil moisture content is 16.7%), after mixing, the soil is paved at room temperature in the air, and the paving thickness is not more than 0.5m, and the heap is turned and stirred every 3 days. The leachate was added to keep the moisture content in the mixed soil unchanged. During the paving process, samples were taken every ten days for testing. When the sixth sampling (that is, when the improvement time was 60 days), the mixed soil was detected. When the organic matter content of the organic soil is greater than 3%, the improvement is terminated.

(4) Improvement effect

The soil properties before and after the improvement of the low organic matter soil are shown in Table 1, and the heavy metal content in the soil is shown in Table 2;

Table 1 Soil properties of low organic matter soil before and after improvement

Table 2 Content of heavy metals in soil before and after improvement of low organic matter soil

It can be seen from the above data that the leachate improvement of low organic matter soil can effectively increase its organic matter content and nitrogen content, and will not cause a significant increase in soil heavy metal content. Therefore, the use of stable leachate to improve low-organic soil is an economical and effective solution.

Example 2:

(1) Characteristics of low organic matter soil

The object of improvement in this example is barren soil with soil organic matter content below 1%, and typical features are: bulk density 1.2-1.5 g/cm ³ , moisture content 6-8%, pH 7.8-8.2, and organic matter content 0.7-0.9%.

(2) Characteristics of stable leachate

The leachate selected in this example is a domestic waste landfill leachate that has been stably stored in a storage tank, and its typical characteristics are: pH 7.5-8.0; alkalinity 7000-8000 mgCaCO ₃ /L; COD _Cr 5000-5500 mg/L ; BOD ₅ 150～200mg/L; B/C 0.03.

(3) Composition ratio

In the present invention, the mass ratio of low-organic soil to leachate is required to be 2.5-5.3, that is, the soil moisture content after mixing is 16-28%, and the low-organic soil content is 72-84%. In this example, the mass ratio of low organic matter soil to leachate is 4:1, and the moisture content of the mixed soil is 20% at this time.

(4) Improvement method

The domestic waste landfill leachate of the above-mentioned characteristics is dripped onto the surface of the low-organic soil with the above-mentioned characteristics to realize the mixing of the leachate and the low-organic soil, wherein the mass ratio of the low-organic soil and the leachate mixed is 4:1 (that is, mixed. The soil moisture content is 20%), after mixing, the soil is paved at room temperature in the air, the thickness of the paving is not more than 0.5m, and the pile is turned and stirred every 3 days. The leachate was added to keep the moisture content in the mixed soil unchanged. During the paving process, samples were taken every ten days for testing. At the fifth sampling (that is, when the improvement time was 50 days), the mixed soil was detected. When the organic matter content of the organic soil is greater than 3%, the improvement is terminated.

(4) Improvement effect

The soil properties before and after the improvement of the low organic matter soil are shown in Table 3, and the heavy metal content in the soil is shown in Table 4;

Table 3 Soil properties of low organic matter soil before and after improvement

Table 4 Heavy metal content in soil before and after improvement of low organic matter soil

It can be seen from the above data that the leachate improvement of low organic matter soil can effectively increase its organic matter content and nitrogen content, and will not cause a significant increase in soil heavy metal content. Therefore, the use of stable leachate to improve low-organic soil is an economical and effective solution.

Example 3:

(1) Characteristics of low organic matter soil

The object of improvement in this embodiment is barren soil with soil organic matter content below 1%, and typical features are: bulk density 1.4-1.7 g/cm ³ , moisture content 8-10%, pH 8.2-8.5, and organic matter content 0.6-0.8%. .

(2) Characteristics of stable leachate

The leachate selected in this example is a domestic waste landfill leachate that has been stably stored in a storage tank, and its typical characteristics are: pH 7.5-7.8; alkalinity 7000-7500mgCaCO ₃ /L; COD _Cr : 6000-6500mg/ L; BOD ₅ 150～170mg/L; B/C 0.025.

(3) Composition ratio

In the present invention, the mass ratio of low-organic soil to leachate is required to be 2.5-5.3, that is, the soil moisture content after mixing is 16-28%, and the low-organic soil content is 72-84%. In this example, the mass ratio of low organic matter soil to leachate is 3:1, and the moisture content of the mixed soil is 25% at this time.

(4) Improvement method

The domestic waste landfill leachate of the above-mentioned characteristics is dripped onto the surface of the low-organic soil with the above-mentioned characteristics to realize the mixing of the leachate and the low-organic soil, wherein the mass ratio of the low-organic soil and the leachate mixed is 3:1 (i.e. mixed. The soil moisture content is 25%), after mixing, the soil is paved at room temperature in the air, the thickness of the paving is not more than 0.5m, and the pile is turned and stirred every 3 days, and the mixed soil is continuously added to the mixed soil as the water in the mixed soil decreases. Add leachate to keep the water content in the mixed soil unchanged. During the paving process, samples were taken every ten days for testing. The fourth sampling (that is, when the improvement time was 40 days), the mixed soil was detected. When the organic matter content of the organic soil is greater than 3%, the improvement is terminated.

(4) Improvement effect

The soil properties before and after the improvement of the low organic matter soil are shown in Table 5, and the content of heavy metals in the soil is shown in Table 6;

Table 5 Soil properties of low organic matter soil before and after improvement

Table 6 Contents of heavy metals in soil before and after improvement of low organic matter soil

It can be seen from the above data that the leachate improvement of low organic matter soil can effectively increase its organic matter content and nitrogen content, and will not cause a significant increase in soil heavy metal content. Therefore, the use of stable leachate to improve low-organic soil is an economical and effective solution.

Comparative Example 1:

Take the same domestic waste landfill leachate and low organic soil as in Example 1, and spray the domestic waste landfill leachate to the surface of the low organic soil with the above characteristics to realize the mixing of the leachate and the low organic soil, wherein the low The mass ratio of organic soil and leachate mixed is 6:1 (that is, the moisture content of the mixed soil is 14%). After mixing, the soil is spread and placed in the air at room temperature, and is continuously added to the mixed soil as the water in the mixed soil decreases. Leachate to keep the water content in the mixed soil unchanged, and stop the good soil after 60 days of paving. The soil properties before and after the improvement of the low organic matter soil are shown in Table 7, and the content of heavy metals in the soil is shown in Table 8;

Table 7 Soil properties of low organic matter soil before and after improvement

Table 8 Heavy metal content in soil before and after improvement of low organic matter soil

When the low-organic soil and the leachate were mixed at a mass ratio of 6:1, after 60 days of improved cultivation, it was detected that the organic matter content of the organic soil in the mixed soil was still less than 3%, and the increase of nitrogen was only 5.6%. The effect is much smaller than that of Example 1.

Comparative Example 2:

The low organic matter soil is mixed with the leachate, wherein the mass ratio of the low organic matter soil to the leachate is less than 2.5:1.

Since when the mass ratio of low organic matter soil and leachate is 2.5:1, the moisture content of the mixed soil is 28.6%, and the maximum field water holding capacity of the adjacent soil (the maximum field water holding capacity after the improvement of the low organic matter soil is 280- 290g/kg, that is, the moisture content at this time is about 28-29%), so when the mass ratio of low organic matter soil and leachate mixed is less than 2.5:1, there is a risk of leachate overflow causing pollution to the surrounding environment.

It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effect; as long as it meets the needs of use, it is within the protection scope of the present invention.

Claims (5)

1. a low-organic soil improvement method, is characterized in that, the step is: by the low-organic soil with organic matter content lower than 1% and biochemical oxygen demand: chemical oxygen demand is less than the domestic waste landfill leachate of 0.1 according to quality The ratio is (2.5 to 5.3): 1 mixed, the mixed soil is paved and placed under aerobic conditions, and as the water in the mixed soil decreases, domestic waste landfill leachate is continuously added to the mixed soil to keep the mixed soil The water content in the mixed soil remains unchanged until the organic matter content of the organic soil in the mixed soil is greater than 3%; the characteristics of the domestic waste landfill leachate are: pH 7.5-8.3; alkalinity 7000-9000 mgCaCO ₃ /L; COD _Cr 4000～6500mg/L; BOD ₅ 120～200mg/L, biochemical oxygen demand: chemical oxygen demand is less than 0.1; the characteristics of the low organic matter soil are: bulk density 1.0～1.7g/cm ³ , field water holding capacity is less than 25 %, pH 7.5～8.5, organic matter content is less than 1%. 2 . The method for improving low-organic soil according to claim 1 , wherein the domestic waste landfill leachate is stored or treated in a storage tank to reach a stable state. 3 . 3. The low-organic soil improvement method as claimed in claim 1 or 2, wherein the aerobic condition refers to that the mixed soil is spread and placed in the air at room temperature, and the thickness of the spread is not more than 0.5m, and the thickness is not more than 0.5m. Stir every day. 4. The method for improving low-organic soil according to claim 1 or 2, wherein the domestic waste landfill leachate is irrigated to the surface of the low-organic soil to be mixed with the low-organic soil. 5 . The method for improving low organic matter soil according to claim 4 , wherein the irrigation method is furrow irrigation or drip irrigation. 6 .

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