1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific know... more 1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu
Anaerobic potentially mineralizable nitrogen (PMN) combined with preplant nitrate test (PPNT) or ... more Anaerobic potentially mineralizable nitrogen (PMN) combined with preplant nitrate test (PPNT) or pre‐sidedress nitrate test (PSNT) may improve corn (Zea mays L.) N management. Forty‐nine corn N response studies were conducted across the U.S. Midwest to evaluate the capacity of PPNT and PSNT to predict grain yield, N uptake, and economic optimal N rate (EONR) when adjusted by soil sampling depth, soil texture, temperature, PMN, and initial NH4–N from PMN analysis. Pre‐plant soil samples were obtained for PPNT (0‐ to 30‐, 30‐ to 60‐, 60‐ to 90‐cm depths) and PMN (0‐ to 30‐cm depth) before corn planting and N fertilization. In‐season soil samples were obtained at the V5 corn development stage for PSNT (0‐ to 30‐, 30‐ to 60‐cm depths) at 0 kg N ha−1 at‐planting rate and for PMN when 0 and 180 kg N ha−1 was applied at planting. Grain yield, N uptake, and EONR were best predicted when separating soils by texture or sites by annual growing degree‐days and including PMN and initial NH4–N wi...
ABSTRACT Potato yield and quality are highly dependent on an adequate supply of water. In this st... more ABSTRACT Potato yield and quality are highly dependent on an adequate supply of water. In this study, 3 years of information from thermal and RGB images were collected to evaluate water status in potato fields. Irrigation experiments were conducted in commercial potato fields (Desiree; drippers). Two water-deficit scenarios were tested: a short-term water deficit (by suppressing irrigation for a number of days before image acquisition), and a long-term cumulative water deficit. Ground and aerial images were acquired in various phenological stages along the potato growing season. Effects of irrigation treatments were recorded by thermal indices and biophysical measurements of stomatal conductance (SC), leaf water potential, leaf osmotic potential and gravimetric water potential in soil. Canopy temperature was delineated from the thermal images with and without fused information from the RGB image. Crop water stress index (CWSI) was calculated, using three forms of minimum baseline temperature: empirical, theoretical and statistical. An empirical evaluation of maximum baseline temperature of Tair + 7 °C was used in all CWSI forms examined. Statistical tests and comparison of CWSI with biophysical measurements were performed to evaluate the responses to irrigation treatments. The results indicated a high correlation of CWSI with SC from tuber initiation to maturity based on ground and aerial data (0.64 ≤ R2 ≤ 0.99). Similar trends of increasing CWSI from well to deficit-irrigated treatments were found in all three growing seasons. The results also showed that CWSI may be calculated based merely on thermal imagery data.
ABSTRACT The nitrogen sufficiency index (NSI) can be used for in-season variable rate management ... more ABSTRACT The nitrogen sufficiency index (NSI) can be used for in-season variable rate management of nitrogen (N) fertilizer to maintain productivity of potato (Solanum tuberosum, L.) while reducing leaching losses. The objective of this study was to evaluate the implications of using high spatial resolution broad-band imagery for determining N prescriptions at different growth stages. Aerial images were obtained for research plots, as well as for a commercial potato field (59 ha) near Becker, Minnesota on 30, 56 and 79 days after emergence (DAE) with a Redlake MS4100 multispectral camera. In research plots, experimental treatments included five N treatments with varying rates and timing of N fertilizer, and two potato varieties, Russet Burbank and Alpine Russet. Spectral indices investigated in this study adequately predicted N stress based on leaf N concentration (r 2 values within dates ranged from 0.49 to 0.82). On 56 and 79 DAE, the Green Ratio Vegetation Index (GRVI) normalized by an NSI that used the recommended rate and timing from the research plots as a reference showed that most areas of the commercial field did not require supplemental N fertilizer (using an NSI over-sufficiency threshold of 120 %). Based on regional guidelines, N was over-applied to the commercial field, but in situations where N is applied more sparingly, a GRVI NSI threshold of 80 % should be used to identify areas that are most suitable for supplemental N fertilizer. A practical approach and the implications associated with using spectral data for in-season N management are proposed.
During the growing season of 2012, 35 garlic plant samples were submitted to the University of Mi... more During the growing season of 2012, 35 garlic plant samples were submitted to the University of Minnesota Plant Disease Clinic for disease diagnosis. Samples originated from multiple counties throughout Minnesota as well as Iowa, Wisconsin, and South Dakota. Symptoms first appeared at the time plants were starting to produce scapes. Symptoms included leaf discoloration that varied from yellow to purple, plant stunting, and leaf tip necrosis. In severe cases, the plants wilted and died. Bulbs of affected plants ranged from being soft and small to almost normal-looking. Symptoms were similar to those associated with phytoplasma infection in other plants. Total genomic DNA was extracted from 30 symptomatic samples and five asymptomatic leaf samples using a Qiagen DNeasy Plant Mini Kit (Qiagen, Germantown, MD) according to the manufacturer's instructions, and used with the universal phytoplasma primers P1/P7 in a direct PCR assay, and with P1/AYint in a nested PCR assay (2) to yield ...
A 2-yr field experiment was conducted to determine the influence of supplemental N-P-K foliar fer... more A 2-yr field experiment was conducted to determine the influence of supplemental N-P-K foliar fertilizers (9-8-7 or 16-2-3) applied during flowering, fruit enlargement and/or flower initiation on yield, quality, and nutrition of Earliglow strawberries (Fragaria × ananassa Duch.). All plots received soil applied fertilizer at planting and at renovation according to soil test recommendations. Foliar fertilizers did not significantly increase total yield at any of the rates or times of application employed. Average yields the first year were 1.5 times greater than those the second year, regardless of whether foliar fertilizers were applied. Treatments did not significantly affect mean berry weight or percent soluble solids. Concentrations of N and P in recently matured leaves sampled during harvest were not significantly affected by foliar treatments, but K level was increased in the second year of the study by some foliar treatments.Key words: Fragaria spp., foliar nutrient sprays, ni...
Arugula (Eruca sativa), mizuna (Brassica rapa var. nipponsinca), red giant mustard (Brassica junc... more Arugula (Eruca sativa), mizuna (Brassica rapa var. nipponsinca), red giant mustard (Brassica juncea), and spinach (Spinaciaoleracea “Tyee”) are fresh produce crops high in nutritive value that provide shortfall and high interest nutrients addressed in the U.S. Dietary Guidelines. The primary objective of this project was to evaluate fertility treatments unique to these crops that optimize their nutritional capacity. Measurements discussed include: vitamin C, dietary fiber, calcium, iron, potassium, sodium, and nitrate. Plants were grown at the University of Minnesota St. Paul Campus (St. Paul, MN) in a greenhouse from November to April under an 18 h photoperiod and a 24/13°C day/night temperature. Plants were grown using five different fertility treatments, including four organic treatments and one conventional control. The plant treatment combinations were replicated three times and the entire experiment was duplicated. Fertility treatments had a high impact on vitamin C (with over...
Potato (Solanum tuberosum L.) production in irrigated coarse-textured soils requires intensive ni... more Potato (Solanum tuberosum L.) production in irrigated coarse-textured soils requires intensive nitrogen (N) fertilization which may increase reactive N losses. Biological soil additives including N-fixing microbes (NFM) have been promoted as a means to increase crop N use efficiency, though few field studies have evaluated their effects, and none have examined the combined use of NFM with microbial inhibitors. A 2-year study (2018-19) in an irrigated loamy sand quantified the effects of the urease inhibitor NBPT, the nitrification inhibitor DMPSA, NFM, and the additive combinations DMPSA + NBPT and DMPSA + NFM on potato performance and growing season nitrous oxide (N2O) emissions and nitrate (NO3-) leaching. All treatments, except a zero-N control, received diammonium phosphate at 45 kg N ha-1 and split applied urea at 280 kg N ha-1. Compared with urea alone, DMPSA + NBPT reduced NO3- leaching and N2O emissions by 25% and 62%, respectively, and increased crop N uptake by 19% in one year, although none of the additive treatments increased tuber yields. The DMPSA and DMPSA + NBPT treatments had greater soil ammonium concentration, and all DMPSA-containing treatments consistently reduced N2O emissions, compared to urea-only. Use of NBPT by itself reduced NO3- leaching by 21% across growing seasons and N2O emissions by 37% in 2018 relative to urea-only. In contrast to the inhibitors, NFM by itself increased N2O by 23% in 2019; however, co-applying DMPSA with NFM reduced N2O emissions by ≥ 50% compared to urea alone. These results demonstrate that DMPSA can mitigate N2O emissions in potato production systems and that DMPSA + NBPT can reduce both N2O and NO3- losses and increase the N supply for crop uptake. This is the first study to show that combining a nitrification inhibitor with NFM can result in decreased N2O emissions in contrast to unintended increases in N2O emissions that can occur when NFM is applied by itself.
Efforts to mitigate the nitrogen (N) footprint of maize production include using N‐fixing microbe... more Efforts to mitigate the nitrogen (N) footprint of maize production include using N‐fixing microbes (NFM) and/or microbial inhibitors. We quantified the effects of NFM, the nitrification inhibitor (NI) 2‐(N‐3,4‐dimethyl‐1H‐pyrazol‐1‐yl) succinic acid isomeric mixture, and the urease inhibitor (UI) N‐(n‐butyl) thiophosphoric triamide, each applied by itself or paired with another additive, on nitrous oxide (N2O) emissions, nitrate (NO3−) leaching, and crop performance in contrasting irrigated and rainfed maize systems over two growing seasons. We also used published emission factors to estimate indirect N2O emissions from leached NO3− that can be converted to N2O. Agronomic effects were relatively small; the NI + NFM treatment increased N use efficiency and grain yield and protein content in some cases by 11%–14% relative to a treatment receiving only urea. Most of the additive treatments reduced direct (in‐field) N2O emissions, most consistently for treatments that contained NI which reduced emissions by 24%–77%. However, these beneficial effects were counteracted by increased NO3− leaching, which occurred most consistently with UI or NFM applied as single additives or with NI. In these treatments, NO3− leaching increased during at least one growing season, and at both sites, by factors of 2–7. In three site‐years, increased NO3− leaching with NFM and NI + NFM offset large reductions in direct N2O, such that total direct + indirect N2O emissions were not different from that in the urea only treatment. These unintended effects may have resulted from unfavorable rainfall timing, varying crop N demand, and declining additive effectiveness. Use of these soil additives requires caution and further study.
The two fertilizer nutrients primarily involved, nitrogen and phospholUs, are needed by all plant... more The two fertilizer nutrients primarily involved, nitrogen and phospholUs, are needed by all plants for healthy growth. Although an individual lawn or garden seems small, the total area of lawns and gardens in urban environments can be significant. Runoff and drainage waters carrying these nutrients may move over hard-surfaced streets where there is no soil to act as a filter. The potential result is an increase in pollution problems.
1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific know... more 1 online resource (PDF, 4 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu
Anaerobic potentially mineralizable nitrogen (PMN) combined with preplant nitrate test (PPNT) or ... more Anaerobic potentially mineralizable nitrogen (PMN) combined with preplant nitrate test (PPNT) or pre‐sidedress nitrate test (PSNT) may improve corn (Zea mays L.) N management. Forty‐nine corn N response studies were conducted across the U.S. Midwest to evaluate the capacity of PPNT and PSNT to predict grain yield, N uptake, and economic optimal N rate (EONR) when adjusted by soil sampling depth, soil texture, temperature, PMN, and initial NH4–N from PMN analysis. Pre‐plant soil samples were obtained for PPNT (0‐ to 30‐, 30‐ to 60‐, 60‐ to 90‐cm depths) and PMN (0‐ to 30‐cm depth) before corn planting and N fertilization. In‐season soil samples were obtained at the V5 corn development stage for PSNT (0‐ to 30‐, 30‐ to 60‐cm depths) at 0 kg N ha−1 at‐planting rate and for PMN when 0 and 180 kg N ha−1 was applied at planting. Grain yield, N uptake, and EONR were best predicted when separating soils by texture or sites by annual growing degree‐days and including PMN and initial NH4–N wi...
ABSTRACT Potato yield and quality are highly dependent on an adequate supply of water. In this st... more ABSTRACT Potato yield and quality are highly dependent on an adequate supply of water. In this study, 3 years of information from thermal and RGB images were collected to evaluate water status in potato fields. Irrigation experiments were conducted in commercial potato fields (Desiree; drippers). Two water-deficit scenarios were tested: a short-term water deficit (by suppressing irrigation for a number of days before image acquisition), and a long-term cumulative water deficit. Ground and aerial images were acquired in various phenological stages along the potato growing season. Effects of irrigation treatments were recorded by thermal indices and biophysical measurements of stomatal conductance (SC), leaf water potential, leaf osmotic potential and gravimetric water potential in soil. Canopy temperature was delineated from the thermal images with and without fused information from the RGB image. Crop water stress index (CWSI) was calculated, using three forms of minimum baseline temperature: empirical, theoretical and statistical. An empirical evaluation of maximum baseline temperature of Tair + 7 °C was used in all CWSI forms examined. Statistical tests and comparison of CWSI with biophysical measurements were performed to evaluate the responses to irrigation treatments. The results indicated a high correlation of CWSI with SC from tuber initiation to maturity based on ground and aerial data (0.64 ≤ R2 ≤ 0.99). Similar trends of increasing CWSI from well to deficit-irrigated treatments were found in all three growing seasons. The results also showed that CWSI may be calculated based merely on thermal imagery data.
ABSTRACT The nitrogen sufficiency index (NSI) can be used for in-season variable rate management ... more ABSTRACT The nitrogen sufficiency index (NSI) can be used for in-season variable rate management of nitrogen (N) fertilizer to maintain productivity of potato (Solanum tuberosum, L.) while reducing leaching losses. The objective of this study was to evaluate the implications of using high spatial resolution broad-band imagery for determining N prescriptions at different growth stages. Aerial images were obtained for research plots, as well as for a commercial potato field (59 ha) near Becker, Minnesota on 30, 56 and 79 days after emergence (DAE) with a Redlake MS4100 multispectral camera. In research plots, experimental treatments included five N treatments with varying rates and timing of N fertilizer, and two potato varieties, Russet Burbank and Alpine Russet. Spectral indices investigated in this study adequately predicted N stress based on leaf N concentration (r 2 values within dates ranged from 0.49 to 0.82). On 56 and 79 DAE, the Green Ratio Vegetation Index (GRVI) normalized by an NSI that used the recommended rate and timing from the research plots as a reference showed that most areas of the commercial field did not require supplemental N fertilizer (using an NSI over-sufficiency threshold of 120 %). Based on regional guidelines, N was over-applied to the commercial field, but in situations where N is applied more sparingly, a GRVI NSI threshold of 80 % should be used to identify areas that are most suitable for supplemental N fertilizer. A practical approach and the implications associated with using spectral data for in-season N management are proposed.
During the growing season of 2012, 35 garlic plant samples were submitted to the University of Mi... more During the growing season of 2012, 35 garlic plant samples were submitted to the University of Minnesota Plant Disease Clinic for disease diagnosis. Samples originated from multiple counties throughout Minnesota as well as Iowa, Wisconsin, and South Dakota. Symptoms first appeared at the time plants were starting to produce scapes. Symptoms included leaf discoloration that varied from yellow to purple, plant stunting, and leaf tip necrosis. In severe cases, the plants wilted and died. Bulbs of affected plants ranged from being soft and small to almost normal-looking. Symptoms were similar to those associated with phytoplasma infection in other plants. Total genomic DNA was extracted from 30 symptomatic samples and five asymptomatic leaf samples using a Qiagen DNeasy Plant Mini Kit (Qiagen, Germantown, MD) according to the manufacturer's instructions, and used with the universal phytoplasma primers P1/P7 in a direct PCR assay, and with P1/AYint in a nested PCR assay (2) to yield ...
A 2-yr field experiment was conducted to determine the influence of supplemental N-P-K foliar fer... more A 2-yr field experiment was conducted to determine the influence of supplemental N-P-K foliar fertilizers (9-8-7 or 16-2-3) applied during flowering, fruit enlargement and/or flower initiation on yield, quality, and nutrition of Earliglow strawberries (Fragaria × ananassa Duch.). All plots received soil applied fertilizer at planting and at renovation according to soil test recommendations. Foliar fertilizers did not significantly increase total yield at any of the rates or times of application employed. Average yields the first year were 1.5 times greater than those the second year, regardless of whether foliar fertilizers were applied. Treatments did not significantly affect mean berry weight or percent soluble solids. Concentrations of N and P in recently matured leaves sampled during harvest were not significantly affected by foliar treatments, but K level was increased in the second year of the study by some foliar treatments.Key words: Fragaria spp., foliar nutrient sprays, ni...
Arugula (Eruca sativa), mizuna (Brassica rapa var. nipponsinca), red giant mustard (Brassica junc... more Arugula (Eruca sativa), mizuna (Brassica rapa var. nipponsinca), red giant mustard (Brassica juncea), and spinach (Spinaciaoleracea “Tyee”) are fresh produce crops high in nutritive value that provide shortfall and high interest nutrients addressed in the U.S. Dietary Guidelines. The primary objective of this project was to evaluate fertility treatments unique to these crops that optimize their nutritional capacity. Measurements discussed include: vitamin C, dietary fiber, calcium, iron, potassium, sodium, and nitrate. Plants were grown at the University of Minnesota St. Paul Campus (St. Paul, MN) in a greenhouse from November to April under an 18 h photoperiod and a 24/13°C day/night temperature. Plants were grown using five different fertility treatments, including four organic treatments and one conventional control. The plant treatment combinations were replicated three times and the entire experiment was duplicated. Fertility treatments had a high impact on vitamin C (with over...
Potato (Solanum tuberosum L.) production in irrigated coarse-textured soils requires intensive ni... more Potato (Solanum tuberosum L.) production in irrigated coarse-textured soils requires intensive nitrogen (N) fertilization which may increase reactive N losses. Biological soil additives including N-fixing microbes (NFM) have been promoted as a means to increase crop N use efficiency, though few field studies have evaluated their effects, and none have examined the combined use of NFM with microbial inhibitors. A 2-year study (2018-19) in an irrigated loamy sand quantified the effects of the urease inhibitor NBPT, the nitrification inhibitor DMPSA, NFM, and the additive combinations DMPSA + NBPT and DMPSA + NFM on potato performance and growing season nitrous oxide (N2O) emissions and nitrate (NO3-) leaching. All treatments, except a zero-N control, received diammonium phosphate at 45 kg N ha-1 and split applied urea at 280 kg N ha-1. Compared with urea alone, DMPSA + NBPT reduced NO3- leaching and N2O emissions by 25% and 62%, respectively, and increased crop N uptake by 19% in one year, although none of the additive treatments increased tuber yields. The DMPSA and DMPSA + NBPT treatments had greater soil ammonium concentration, and all DMPSA-containing treatments consistently reduced N2O emissions, compared to urea-only. Use of NBPT by itself reduced NO3- leaching by 21% across growing seasons and N2O emissions by 37% in 2018 relative to urea-only. In contrast to the inhibitors, NFM by itself increased N2O by 23% in 2019; however, co-applying DMPSA with NFM reduced N2O emissions by ≥ 50% compared to urea alone. These results demonstrate that DMPSA can mitigate N2O emissions in potato production systems and that DMPSA + NBPT can reduce both N2O and NO3- losses and increase the N supply for crop uptake. This is the first study to show that combining a nitrification inhibitor with NFM can result in decreased N2O emissions in contrast to unintended increases in N2O emissions that can occur when NFM is applied by itself.
Efforts to mitigate the nitrogen (N) footprint of maize production include using N‐fixing microbe... more Efforts to mitigate the nitrogen (N) footprint of maize production include using N‐fixing microbes (NFM) and/or microbial inhibitors. We quantified the effects of NFM, the nitrification inhibitor (NI) 2‐(N‐3,4‐dimethyl‐1H‐pyrazol‐1‐yl) succinic acid isomeric mixture, and the urease inhibitor (UI) N‐(n‐butyl) thiophosphoric triamide, each applied by itself or paired with another additive, on nitrous oxide (N2O) emissions, nitrate (NO3−) leaching, and crop performance in contrasting irrigated and rainfed maize systems over two growing seasons. We also used published emission factors to estimate indirect N2O emissions from leached NO3− that can be converted to N2O. Agronomic effects were relatively small; the NI + NFM treatment increased N use efficiency and grain yield and protein content in some cases by 11%–14% relative to a treatment receiving only urea. Most of the additive treatments reduced direct (in‐field) N2O emissions, most consistently for treatments that contained NI which reduced emissions by 24%–77%. However, these beneficial effects were counteracted by increased NO3− leaching, which occurred most consistently with UI or NFM applied as single additives or with NI. In these treatments, NO3− leaching increased during at least one growing season, and at both sites, by factors of 2–7. In three site‐years, increased NO3− leaching with NFM and NI + NFM offset large reductions in direct N2O, such that total direct + indirect N2O emissions were not different from that in the urea only treatment. These unintended effects may have resulted from unfavorable rainfall timing, varying crop N demand, and declining additive effectiveness. Use of these soil additives requires caution and further study.
The two fertilizer nutrients primarily involved, nitrogen and phospholUs, are needed by all plant... more The two fertilizer nutrients primarily involved, nitrogen and phospholUs, are needed by all plants for healthy growth. Although an individual lawn or garden seems small, the total area of lawns and gardens in urban environments can be significant. Runoff and drainage waters carrying these nutrients may move over hard-surfaced streets where there is no soil to act as a filter. The potential result is an increase in pollution problems.
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