Austrian Winter Pea Research Articles

Nitrous oxide fluxes during a winter cover crop season in a Mississippi corn cropping system

Agroecosystems are the largest source of anthropogenic N2O fluxes. While cover crops (CC) offer benefits for soil health, their impacts on greenhouse gas fluxes are inconsistent. In the southeastern US, where intensive agriculture and low CC adoption are prevalent, few studies have investigated CC impact on soil N2O fluxes. Our study explored the effects of CC species and management practices on soil N2O fluxes during the winter CC growing season in Mississippi, which was conducted in a non-tilled corn cropping system with seven CC treatments. We measured in situ soil N2O fluxes, along with soil moisture and temperature, throughout the CC growing season from 2022 to 2023. Surface soil samples were also collected to analyze soil mineral nitrogen (N) content and enzyme activity. Over the study period (a total of 188 days), cumulative N2O fluxes were 0.50–1.03 ​kg N2O–N ha−1, with the lowest values from the annually-rotated Elbon rye treatment and the highest from the annually-rotated Austrian winter pea. Our results show that both CC treatments and sampling time significantly affected soil N2O fluxes. There was a strong positive correlation (r ​= ​0.34, p ​< ​0.05) between N2O fluxes and NO3–N content, which was lowest under continuous rye and rotated-rye treatments (0.31 and 0.34 ​mg ​kg−1 ). The results suggest that Elbon rye effectively reduced soil N2O fluxes during this period by lowering the soil NO3–N content, the primary substrate for denitrification. This study is one of the few studies to examine the impacts of cover crops on soil N2O fluxes in cropping systems in the southeastern US, offering insights into the cover crop effects on soil N2O fluxes during their growing season.

The Impact of Peach Rootstocks and Winter Cover Crops on Reproduction of Ring Nematode

Two peach rootstocks (‘Guardian’ and ‘MP-29’) and ten winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, and daikon radish) were evaluated in a greenhouse environment to determine their suitability to host ring nematode, Mesocriconema xenoplax. Each crop was inoculated with 500 ring nematodes, and the experiments were terminated 60 days after inoculation. The reproduction factor (ratio of final and initial nematode population) ranged from 0 to 13.8, indicating the crops greatly varied in their host suitability to ring nematode. ‘Guardian’ has been known to tolerate ring nematode; however, results from the current study suggest the tolerance statement is anecdotal. Another peach rootstock, ‘MP-29’, was also a good host for ring nematode, suggesting an urgency to develop ring nematode-resistant peach rootstocks. Wheat supported the least to no nematode reproduction while pea supported the greatest reproduction. The rest of the cover crops were poor to good hosts to ring nematodes. Although planting cover crops in peach orchards is not common, employing non or poor host crops can help suppress nematodes in addition to having soil health benefits. Furthermore, peach breeding programs should focus on finding and introgressing ring nematode resistance in commercial rootstocks.

Cover Crop and Crop Rotation Effects on Tissue and Soil Population Dynamics of Macrophomina phaseolina and Yield Under No-Till System.

The effects of crop rotation and winter cover crops on soybean yield and colony-forming (CFU) units of Macrophomina phaseolina, the causal agent of charcoal rot (CR), are poorly understood. A field trial was conducted from 2011 to 2015 to evaluate (i) the impact of crop rotation consisting of soybean (Glycine max [L.] Merr.) following cotton (Gossypium hirsutum L.), soybean following corn (Zea mays L.), and soybean following soybean over a 2-year rotation and its interaction with cover crop and (ii) the impact of different cover crops on a continuous soybean crop over a 5-year period. This trial was conducted in a field with 10 subsequent years of cover crop and rotation treatments. Cover crops consisted of winter wheat (Triticum aestivum L.) and Austrian winter pea (Pisum sativum L. subsp. sativum var. arvense), hairy vetch (Vicia villosa Roth), and a fallow treatment was evaluated with and without poultry litter application (bio-cover). Tissue CFU of M. phaseolina varied significantly between crop rotation treatments: plots where soybean was grown following cotton had significantly greater tissue CFU than plots following soybean. Poultry litter and hairy vetch cover cropping caused increased tissue CFU, though this effect differed by year and crop rotation treatment. Soil CFU in 2015 was substantially lower compared with 2011. However, under some crop rotation sequences, plots in the fallow treatment had significantly greater soil CFU than plots where hairy vetch and wheat was grown as a cover crop. Yield was greater in 2015 compared with 2011. There was a significant interaction of the previous crop in the rotation with year, and greater yield was observed in plots planted following cotton in the rotation in 2015 but not in 2011. The result from the continuous soybean planted over 5 years showed that there were no significant overall effects of any of the cover crop treatments nor was there interaction between cover crop treatment and year on yield. The lack of significant interaction between crop rotation and cover crop and the absence of significant differences between cover crop treatments in continuous soybean planting suggest that cover crop recommendations for midsouthern soybean growers may need to be independent of crop rotation and be based on long-term crop needs.

Cover crop residue quality regulates litter decomposition dynamics and soil carbon mineralization kinetics in semi-arid cropping systems

Cover crop residue addition provides several soil health benefits and serves as a precursor for storing soil organic carbon (SOC). However, information on residue decomposition dynamics and its contribution to soil carbon (C) and nitrogen (N) cycling in arid and semi-arid environments is limited. This study evaluated cover crop residue decomposition in field conditions and C mineralization kinetics in laboratory conditions. For the field experiment, approximately 20 g of Austrian winter pea (Pisum sativum subsp. arvense L.), turnip (Brassica rapa subsp. rapa L.), and triticale (×Triticosecale Wittmack) cover crop residues were kept in litter bags and placed on the soil surface before subsequent forage sorghum (Sorghum bicolor L. Moench) planting in ongoing cover crops study plots. Litter bags were collected every other week (12 destructive samplings) to evaluate the remaining dry matter and C and N contents. The decomposition data were plotted with first order kinetics and exponential models to describe the model fit. To study C mineralization kinetics, a 10-week incubation was set up in a laboratory with Austrian winter pea, turnip, and triticale cover crops and native grass, wheat, and sorghum residues. Carbon mineralization rates were evaluated with three statistical models (first order kinetics and single and double exponential). The exponential model best described the cover crop residue decomposition kinetics in the field. After 98 days, the residue decomposition was higher with Austrian winter pea (47 %), followed by turnip and triticale with ∼40 % biomass decomposition. Residue types and quality both affected the decomposition rates. The C mineralization rate correlated with initial N content (r = 0.87, P < 0.05), C: N ratio (r = −0.88, P < 0.05), and lignin: N (r = −0.87, P < 0.05). While the single exponential model explained field decomposition dynamics, the double exponential decay model best fitted the observed C mineralization trend among the three models. The decay models from our study can be applied to estimate the decomposition dynamics of other winter cover crop residues in similar agroecosystems. This study demonstrated that selecting suitable cover crops and mixtures is critical for maximizing soil C sequestration and N availability in subsequent crops in cover crop-integrated semi-arid cropping systems.

Determining cardinal temperatures for eight cover crop species

AbstractGrowing degree days (GDD) is a tool to predict plant growth and can be adapted for use in any plant species, including cover crops. A limitation of the GDD calculation is accurate temperature parameters used to predict plant development. For most cover crop species, the cardinal temperatures are not well defined in the literature, leading to a less accurate calculation of GDD. The objective of this study was to determine the cardinal temperatures of eight cover crop species, including Austrian winter pea (Pisum sativum), balansa clover (Trifolium michelianum), barley (Hordeum vulgare), black‐seeded oats (Avena sativa), common vetch (Vicia sativa), cereal rye (Secale cereale), crimson clover (Trifolium incarnatum), and hairy vetch (Vicia villosa), using a growth chamber experiment. Seven different temperature regimes from 4 to 34°C were implemented, and the number of leaves was counted from day 0 to 21. As a result, the data were regressed to estimate the cardinal temperatures for each species. The results of this research identified base (2), optimum (3), and maximum (8) temperatures for cover crops that were not previously reported. Five cardinal temperatures determined in this study were different from what was previously recorded; base and optimum temperatures were −4.5 and 24.8°C for cereal rye, 3.9 and 26.6°C for crimson clover, and the base temperature was 3.4°C for balansa clover. The successful identification of these cardinal temperatures for cover crops will allow the development of plant growth and biomass prediction models to aid in cover crop termination decision support tools.

Cover crop and biofuel crop effects on hydraulic properties for claypan soils

AbstractPerennial biofuel and cover crops systems are important for enhancing soil health and can provide numerous soil, agricultural, and environmental benefits. The study objective was to investigate the effects of cover crops and biofuel crops on soil hydraulic properties relative to traditional management for claypan soils. The study site included selected management practices: cover crop (CC) and no cover crop (NC) with corn/soybean rotation, switchgrass (SW), and miscanthus (MI). The CC mixture consisted of cereal rye, hairy vetch, and Austrian winter pea. The research site was located at Bradford Research Center in Missouri, USA, and was implemented on a Mexico silt loam. Intact soil cores (76‐mm diam. by 76‐mm long) were taken from the 0–10, 10–20, 20–30, and 30–40 cm depths with three plot replicates and two sub‐samples per plot replicate per depth. Soil hydraulic properties evaluated for each sample included: saturated hydraulic conductivity (Ksat), water retention, bulk density, and pore size distributions. Results showed with the test of Duncan's least significant differences that treatments of MI (1.18 Mg m−3) and SW (1.21 Mg m−3) had lower values of bulk density averaging across soil depth than CC (1.27 Mg m−3) and NC (1.31 Mg m−3). Management systems significantly increased Ksat with the biofuel treatments at 0–10 cm compared to NC system. The MI management showed a significant increase in macroporosity and fine mesoporosity as compared to other management systems. Slight changes have occurred in the measured soil physical properties for CC system compared to NC plots. Overall, increasing soil organic matter from more plant roots from long‐term biofuel cropping systems can improve soil water storage and crop productivity.

Multi-Stage Corn Yield Prediction Using High-Resolution UAV Multispectral Data and Machine Learning Models

Timely and cost-effective crop yield prediction is vital in crop management decision-making. This study evaluates the efficacy of Unmanned Aerial Vehicle (UAV)-based Vegetation Indices (VIs) coupled with Machine Learning (ML) models for corn (Zea mays) yield prediction at vegetative (V6) and reproductive (R5) growth stages using a limited number of training samples at the farm scale. Four agronomic treatments, namely Austrian Winter Peas (AWP) (Pisum sativum L.) cover crop, biochar, gypsum, and fallow with sixteen replications were applied during the non-growing corn season to assess their impact on the following corn yield. Thirty different variables (i.e., four spectral bands: green, red, red edge, and near-infrared and twenty-six VIs) were derived from UAV multispectral data collected at the V6 and R5 stages to assess their utility in yield prediction. Five different ML algorithms including Linear Regression (LR), k-Nearest Neighbor (KNN), Random Forest (RF), Support Vector Regression (SVR), and Deep Neural Network (DNN) were evaluated in yield prediction. One-year experimental results of different treatments indicated a negligible impact on overall corn yield. Red edge, canopy chlorophyll content index, red edge chlorophyll index, chlorophyll absorption ratio index, green normalized difference vegetation index, green spectral band, and chlorophyll vegetation index were among the most suitable variables in predicting corn yield. The SVR predicted yield for the fallow with a Coefficient of Determination (R2) and Root Mean Square Error (RMSE) of 0.84 and 0.69 Mg/ha at V6 and 0.83 and 1.05 Mg/ha at the R5 stage, respectively. The KNN achieved a higher prediction accuracy for AWP (R2 = 0.69 and RMSE = 1.05 Mg/ha at V6 and 0.64 and 1.13 Mg/ha at R5) and gypsum treatment (R2 = 0.61 and RMSE = 1.49 Mg/ha at V6 and 0.80 and 1.35 Mg/ha at R5). The DNN achieved a higher prediction accuracy for biochar treatment (R2 = 0.71 and RMSE = 1.08 Mg/ha at V6 and 0.74 and 1.27 Mg/ha at R5). For the combined (AWP, biochar, gypsum, and fallow) treatment, the SVR produced the most accurate yield prediction with an R2 and RMSE of 0.36 and 1.48 Mg/ha at V6 and 0.41 and 1.43 Mg/ha at the R5. Overall, the treatment-specific yield prediction was more accurate than the combined treatment. Yield was most accurately predicted for fallow than other treatments regardless of the ML model used. SVR and KNN outperformed other ML models in yield prediction. Yields were predicted with similar accuracy at both growth stages. Thus, this study demonstrated that VIs coupled with ML models can be used in multi-stage corn yield prediction at the farm scale, even with a limited number of training data.

Influence of cover crops on soybean yield and partial returns as an alternative to double‐crop soybean in Arkansas

AbstractThe number of hectares dedicated to winter wheat (Triticum aestivum L.) in the southern United States has been trending downward for almost a decade, presenting an opportunity for producers to utilize alternatives in their soybean [Glycine max (L.) Merr.] rotations, such as winter cover crops. A study was established to compare the cover crops to traditional cropping systems by determining the effect each had on a successive soybean crop and to examine partial economic returns. Cropping systems implemented were winter fallow, winter wheat, and seven cover crop treatments, including cereal rye (Secale cereale L.), black‐seeded oat (Avena sativa L.), barley (Hordeum vulgare L.), Austrian winter pea (Pisum sativum L.), blue lupin (Lupinus angustifolius L.), Blend 1 (cereal rye, crimson clover [Trifolium incarnatum L.], seven‐top turnip [Brassica rapa L.]). and Blend 2 (black‐seeded oats and Austrian winter pea). The winter cropping system did not affect the soybean plant population (p = 0.32). Soybean grain yield varied among the different winter cropping systems (p &lt; 0.01) with yields ranging from 3346 to 3906 kg ha−1. The soybean double‐crop system ($1383.02 ha−1) and soybean following winter cover crops ($1239–1380 ha−1) produced similar partial returns but both were greater than soybean following winter fallow ($1217.81 ha−1) (p &lt; 0.01). Soybean yields and partial returns were the highest when following Blend 2. Results of this study showed that winter cover crops can provide an adequate alternative to both winter fallow and traditional winter wheat soybean double‐crop systems in the mid‐southern United States.

Simulated effects of cover crops with no-tillage on soil and crop productivity in rainfed semi-arid cotton production systems

Cover cropping and no-tillage (NT) practices are promoted for soil health and environmental benefits. However, producing enough quantity of biomass to meet expected benefits can be a challenge in semi-arid cropping systems where water resources are limited, and producers have lingering questions regarding cover crop selection, termination timings, water use, and their subsequent effect on cash crop. The objective of this study was to assess the impacts of cover crops with NT on soil and crop productivity in a rainfed, continuous cotton (Gossypium hirsutum L.) system using the Denitrification Decomposition (DNDC) model. Treatments included: (a) conventional till (CT); (b) NT, and NT with the following cover crops: (c) Austrian winter pea (Pisum sativum L.) (Pea); (d) crimson clover (Trifolium incarnatum L.) (Clover); (e) hairy vetch (Vicia villosa L.) (Vetch); (f) a multi-species mixture (Mixture); and (g) winter wheat (Triticum aestivum L.) (Wheat). The DNDC model adequately simulated the seed cotton yield and cover crop biomass during calibration (root mean square error (RMSE) = 200 and 398 kg ha−1, respectively) and validation (RMSE = 277 and 270 kg ha−1, respectively). Stocks of soil organic carbon (SOC) and total nitrogen (TN) were simulated with Nash–Sutcliffe efficiency (NSE) of 0.91 and 0.78 during calibration, and with NSE of 0.88 and 0.75, respectively during validation. Long-term simulations revealed: (1) Vetch and Pea produced greater biomass and hence highest SOC and TN contents, which was followed by Mixture, Wheat, and Clover; (2) cotton yield in cover crop treatments was no different to that in non-cover crop treatments when cover crop was terminated about six weeks prior to cotton planting; (3) later termination of cover crops can result in greater cotton yield loss due to soil water depletion by cover crops. Overall, this study highlights the potential of conservation practices, such as cover crops and NT to improve soil health without significant loss in cotton yields.

Winter cover crop impact on soil health in Texas Rolling Plains dryland cotton

AbstractThe Rolling Plains of Texas are historically semi‐arid with sporadic, high intensity storms followed by periods of long drought. Fallow management is a common practice intended to store soil water, but leaves the bare soil exposed to erosive forces that can diminish the soil productivity. Cover crops in no‐till (NT) agriculture have been proposed to increase soil health under environments with low precipitation as an alternative to fallow management. This study evaluated multiple treatments in a dryland cotton system including: (1) conventional tillage (CT); (2) NT; and NT with the following cover crops: (3) wheat; (4) Austrian winter pea; (5) crimson clover; (6) hairy vetch; and (7) mixed species cover. Soil samples were collected at 0, 3, and 6 weeks after cover crop termination and analyzed for soil organic carbon, total nitrogen, inorganic N, water‐extractable organic carbon, water‐extractable organic nitrogen, carbon mineralization, and phospholipid fatty acid analysis. For all parameters tested, there was no significant difference between CT and NT at any date or depth, so the addition of cover crops to NT cotton systems might be needed in order to enhance NT in regard to soil function. The multi‐species mixed treatment was predicted to perform the best out of the cover crop treatments due to its combined benefits from grasses and legumes. However, the single‐species Austrian winter pea treatment had 24% and 28% higher soil carbon and nitrogen than no‐till without a cover crop, and can be a useful alternative to fallow management under these dryland agriculture conditions.

Can relative sensitivity of cover crop species to chloroacetamide and pyrazole herbicides be exploited to design interseeding mixtures?

AbstractDrill-interseeding cover crops into standing corn (V3 to V5 growth stage) provides opportunities for increasing functional diversity in cropping systems by facilitating use of cover crop mixtures that include grass, legume, and brassica species. Designing herbicide-based weed control programs that negotiate tradeoffs between crop protection and environmental goals when interseeding mixtures remains a major challenge. The objective of this study was to use greenhouse-based dose-response assays to describe the relative sensitivity of 12 cover crop species that differ in traits, including taxonomic group and seed mass, to chloroacetamide (acetochlor, dimethenamid, S-metolachlor; Group 15 herbicides as categorized by the Weed Science Society of America) and pyrazole (pyroxasulfone; Group 15) herbicides. Nonlinear models were fit, and effective doses were estimated (ED50) to compare relative sensitivities of cover crop species to each herbicide. Brassica species (winter canola, Dwarf Essex rape, daikon radish) were less sensitive than small-seeded legumes (medium red clover, crimson clover) and grasses (annual ryegrass) in response to each chloroacetamide, but similar in response to pyroxasulfone. Austrian winter pea, a large-seeded legume, was less sensitive to each herbicide compared to other legumes (crimson clover, medium red clover, hairy vetch). Cereal rye and triticale were less sensitive to dimethenamid, S-metolachlor, and pyroxasulfone compared to annual ryegrass, but similar sensitivities were observed for acetochlor. These results suggest that relative differences in sensitivity to chloroacetamide and pyrazole herbicides could be exploited when designing cover crop mixtures for interseeding. It is imperative, however, to use these findings in conjunction with field-based observations of cover crop injury potential in interseeded systems.

Fall–winter cover crops promote soil health and weed control in the southeastern clayey soils

AbstractSeven winter cover crops including grasses, legumes, and brassicas were evaluated for biomass production and effects on weed presence, stored soil water, soil health indicators, and the performance of a subsequent soybean [Glycine max (L.) Merr.] crop in the clayey soils of South Carolina during 2019–2020 and 2020–2021. A mixture of Austrian winter pea (Pisum sativum L.), rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa Roth), and oat (Avena sativa L.), a mixture of crimson clover and rye, and single rye ranked high for biomass production. Cover crops did not deplete more soil water than a fallow did (–22 to 8% difference in soil water retention, compared to fallow with or without herbicide application), controlled weeds equally well or better than herbicides (&gt;90% reduction in weed presence, compared to herbicide control), and reduced soil penetration resistance (&gt;40%, compared to fallow with or without herbicide application in the second season). The five‐species mixture also improved soil biological activity (&gt;43% increase in soil respiration at cover‐crop termination, compared to that under a chemical fallow). The subsequent soybean crop's yield was never negatively affected if not improved by the above cover crops (9–173% increase, compared to that following a chemical fallow). Our results indicate the suitability of the above cover crops for the southeastern clayey soils based on biomass production, weed suppression, and improvements in soil health and the subsequent soybean crop's performance and provide the rationale for planting them rather than keeping the land under a chemical fallow.

Winter Wheat Performance Following One-time High Rates of Compost and Annual Cover Crop Planting in Wheat-fallow Rotations

Aims: One-time high rates of compost were applied at 15, 30, and 45 Mg ha-1 to improve soil organic matter (SOM) and fertility in dryland organic winter wheat-fallow rotations. Cover crop mixtures (oats and Austrian winter peas) were planted in fallow phases annually to suppress weeds and reduce repetitive tillage used for weed control because the latter breaks down SOM.&#x0D; Study Design: The experiment was laid-out in a split-plot design with four replications. Fertilizer (compost rates, inorganic fertilizer and no amendment control) and cover crops served as main and sub-plot factors respectively.&#x0D; Place and Duration of Study: The experiment was conducted at the Sustainable Agriculture Research and Extension Center, University of Wyoming, from September 2015 to August 2018.&#x0D; Methodology: Soil samples, weed biomass, wheat yield and protein quality data were collected and analyzed over three years.&#x0D; Results: Results indicated that 45 Mg ha-1 compost increased (P=.05) soil total carbon (TC) and nitrogen (TN) concentrations up to 25 and 19% respectively, in the last two years. Wheat yield was not affected (p&gt;0.05) by compost or cover crops in any growing season but 45 Mg ha-1 compost increased (P=.05) protein quality by 2-9% in the first growing season. Cover crops suppressed weeds while growing in the first growing season but had varying effects on weeds in wheat phases that followed them in rotation. It was noted that soil electrical conductivity levels affected by 45 Mg ha-1 compost was 5 times lower than wheat thresholds; and soil moisture loss by cover crops did not affect wheat yield.&#x0D; Conclusion: 45 Mg ha-1 compost improves soil fertility and SOM in the short term. However, significant reflection of soil changes in wheat yield may take longer time. Further research is needed to effectively integrate cover crops as a weed control measure in dryland organic wheat-fallow rotations.

Cover Crops Enhance Soil Properties in Arid Agroecosystem despite Limited Irrigation

Cover crops (CCs) can enhance the sustainability and resiliency of agroecosystems by providing multiple ecosystem benefits, including soil quality improvement. However, in areas with limited precipitation such as the southwestern USA, cover cropping is challenging. With limited water, it may be difficult to raise cover crops for realizing ecosystem benefits. Research was conducted at two sites in New Mexico over two years to determine if CC under limited irrigation could produce enough biomass to improve soil quality. Treatments included a fallow (control) and monocultures of barley (Hordeum vulgare), Austrian winter peas (Pisum sativum subsp. arvense), mustard (Brassica rapa, var. Caliente 199), and a three-way mixture of these species, grown under three different irrigation regimes. The results indicate that the improvement in soil quality measurements by CCs grown under one supplemental irrigation were comparable to those grown under multiple irrigations. All CC treatments improved the soil dry aggregate size distribution from 2018 to 2020. At the end of the study, the MWD of dry aggregates was higher (3.26 mm) in all CC treatments than in the fallows (2.43 mm) at one site, but at the second site, mustard and mix were comparable to the fallows. Wet aggregate stability increased by 19% in the mix between 2018 and 2020 at one site. Pea plots needed about 23 kg ha−1 less N fertilizer for sweet corn production compared to the fallow treatment at one site. This suggests that CCs can be successfully grown under limited water availability in irrigated arid systems of New Mexico while still improving the soil quality.

Winter legume cover effects on yields of biomass‐sorghum and cotton in Georgia

AbstractAmong the many ecosystems services of winter covers, winter legumes have an advantage over winter grain covers by fixing N that may be used by subsequent crops. A 5‐yr study was conducted to compare the biomass yields of five leguminous winter cover crops [Austrian winter pea (Pisum sativum L.), fava bean (Vicia fava L.), narrow‐leaf lupin (Lupinus angustifolius L.), cahaba vetch (Vicia spp.), crimson clover (Trifolium incarnatum L.)] plus rye (Secale cereale L.) and determine the effects of these winter cover crops either harvested or left on the soil on subsequent biomass sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.) yields at two field locations in Georgia. Lupin produced between 4.16 and 9.54 Mg ha−1 biomass, approximately two to four times more than any other cover at both locations every year. Lupin, followed by vetch and winter pea had the greatest positive effect on biomass sorghum yields. Biomass‐sorghum yields after lupin cover were not significantly different whether biomass was retained on the soil by rolling or removed. Seed cotton yields were higher after lupin and vetch . Significantly higher sorghum and cotton yields occurred for rolled covers with crimson clover, winter pea, and fava bean. Averaged over the years and locations, lupin biomass produced approximately 143 kg ha−1 N, more than any other cover. The study suggests that harvested or grazed lupin or vetch covers could give similar benefits to summer row crops compared with traditionally leaving the cover on the soil.

Exploring Overwintered Cover Crops as a Soil Management Tool in Upper-midwest High Tunnels

High tunnels are an important season extension tool for horticultural production in cold climates, however maintaining soil health in these intensively managed spaces is challenging. Cover crops are an attractive management tool to address issues such as decreased organic matter, degraded soil structure, increased salinity, and high nitrogen needs. We explored the effect of winter cover crops on soil nutrients, soil health and bell pepper (Capsicum annuum) crop yield in high tunnels for 2 years in three locations across Minnesota. Cover crop treatments included red clover (Trifolium pratense) monoculture, Austrian winter pea/winter rye biculture (Pisum sativum/Secale cereale), hairy vetch/winter rye/tillage radish (Vicia villosa/S. cereale/Raphanus sativus) polyculture, and a bare-ground, weeded control. Cover crop treatments were seeded in two planting date treatments: early planted treatments were seeded into a standing bell pepper crop in late Aug/early September and late planted treatments were seeded after bell peppers were removed in mid-September At termination time in early May, all cover crops had successfully overwintered and produced biomass in three Minnesota locations except for Austrian winter pea at the coldest location, zone 3b. Data collected include cover crop and weed biomass, biomass carbon and nitrogen, extractable soil nitrogen, potentially mineralizable nitrogen, microbial biomass carbon, permanganate oxidizable carbon, soil pH, soluble salts (EC), and pepper yield. Despite poor legume performance, increases in extractable soil nitrogen and potentially mineralizable nitrogen in the weeks following cover crop residue incorporation were observed. Biomass nitrogen contributions averaged 100 kg·ha−1 N with an observed high of 365 kg·ha−1 N. Cover crops also reduced extractable soil N in a spring sampling relative to the bare ground control, suggesting provision of nitrogen retention ecosystem services.

Corn productivity and profitability in raised stale seedbed systems with and without cover crops

AbstractCover crops are promoted for reducing the negative environmental effects of high‐input row‐crop production; however, cover crop adoption in the mid‐southern United States is low, partly because of a perceived increase in risk. The objective of this research was to determine if cover crops cost‐effectively improved the productivity and water use of corn (Zea mays L.) in raised stale seedbed systems. The effects of four cover crops, namely Austrian winter pea [Pisum sativum var. arvense (L.) Poiret], crimson clover (Trifolium incarnatum L.), cereal rye (Secale cereal L.), and tillage radish (Raphanus sativus L.), in a raised stale seedbed environment on corn grain yield, net returns, and water use efficiency (WUE) were investigated at Stoneville, MS, on a Commerce very fine sandy loam soil (fine‐silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquept). A cover crop preceding corn maintained or decreased yield, net returns, and WUE. Cover crops had no effect on corn grain yield in any year, except for 2017, in which Austrian winter pea and cereal rye decreased yield by 37 and 45%, respectively. Tillage radish never affected net returns; however, the inclusion of Austrian winter pea, crimson clover, or cereal rye reduced net returns by up to 57% in two of four years. Cover crops either maintained or decreased WUE by up to 44%. In the 4 yr of this research, the inclusion of a cover crop in a raised stale seedbed system only maintained or decreased corn grain yield, net returns, and WUE.

Runoff, erosion, and nutrient transport arising from furrow irrigation in a corn conservation production system

AbstractContemporary row‐crop practices in the mid‐southern United States contribute to declining water tables and impairment of downstream waters, threatening the sustainability of irrigated agriculture and vital ecosystem services. This research was conducted to determine whether agro‐hydrology can be altered by cover crop or traffic pattern. The effects of cover crop {Austrian winter pea [Pisum sativum var. arvense (L.) Poiret], crimson clover [Trifolium incarnatum L.], cereal rye [Secale cereal L.], and tillage radish [Raphanus sativus L.]} and traffic pattern (traffic, nontraffic) on runoff, erosion, and nutrient transport from a furrow irrigation event were investigated at Stoneville, MS on a Commerce very fine sandy loam (a fine‐silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquept). Relative to winter fallow, the inclusion of a cover crop reduced erosion by at least 16% but had no effect on runoff or the transport of total P, total Kjeldahl nitrogen (TKN), soluble reactive phosphate (SRP), NH4–N, or NO3–N. Eliminating traffic in furrows reduced runoff, erosion, and SRP transport up to 13%. Traffic pattern had no effect on the transport of total P, TKN, NH4–N, or NO3–N. Regardless of treatment, total N loss never exceeded 0.2% of N applied as inorganic fertilizer. This research demonstrates that cover crop and equipment traffic pattern can be manipulated in reduced tillage systems to improve the sustainability of irrigated agriculture and ecosystem services in the mid‐southern United States.

Biological nitrogen fixation of cool‐season legumes in agronomic systems of the Southern Great Plains

AbstractBiological nitrogen fixation (BNF) is a key ecosystem service rendered by legumes, but quantitative information is lacking regarding BNF in the Texas Rolling Plains (TRP), an easterly portion of U.S. Southern Great Plains where cool‐season legumes can typically be grown as cash or cover crops in dryland conditions. Using three diverse cropping systems studies (Site 1, long‐term cotton [Gossypium hirsutum L.]‐cover crop systems; Site 2, short‐term cotton‐cover crop systems; and Site 3, transitional organic wheat [Triticum aestivum L.] system), our research objective was to quantify and compare BNF and associated parameters among four cool‐season legumes (Austrian winter pea [Pisum sativum subsp. Arvense], hairy vetch [Vicia villosa], crimson clover [Trifolium incarnatum], and lentil [Lens culinaris]) in different settings. At Sites 1 and 2, winter pea had growth of 2.73 to 3.44 Mg ha−1, the greatest percent N derived from the atmosphere (%Ndfa; 57.2–72.6%) and, depending on site, the greatest level of BNF (67–74 kg N ha−1). Results from the organic system (Site 3) demonstrated winter pea was also productive in growth and BNF when intercropped with wheat in N‐poor soil, with exceptionally high %Ndfa (92.7%). Hairy vetch and lentil differed in growth and %Ndfa, but had comparable BNF (46–51 kg N ha−1) at Sites 1 and 2. Growth of crimson clover was poor. This data provides insights on how cool‐season legumes differ in BNF in the TRP in a year when legume growth was average for the region. The TRP has a volatile climate, however, indicating further study is needed to fully understand the BNF benefit cool‐season legumes can provide in the region.

Weed suppression versus water use: Efficacy of cover crops in water‐limited agroecosystems

AbstractWinter cover crops (CC) may facilitate weed management by inhibiting weed seed germination and seedling emergence and suppressing weed growth within the cash crop. In southern New Mexico, with scarce winter precipitation and limited irrigation water, producing sufficient CC biomass for effective weed suppression while conserving water resources is challenging. This study assessed the water requirement to produce a CC with enough biomass for weed suppression benefits during cash crop growth at two locations in New Mexico. Three winter CC species, barley, Austrian winter pea and mustard, grown singly and in a three‐way mix, under three differential irrigation treatments (one, two or three irrigations after emergence) were evaluated for their weed‐suppressive potential. Maize was planted as a cash crop four weeks after winter CC termination. Number of irrigations had no effect on the CC and weed biomass production. All CCs had lower weed density prior to maize planting compared with fallow. Barley and the three‐way mix reduced weed density by 56–96% and 68–95%, respectively. All CC treatments had lower weed biomass at the end of critical period for weed control in maize compared with fallow. Weed biomass at maize harvest did not differ between treatments. The maize yield was consistently higher in conventionally managed, weed‐free subplots, than in unsprayed weedy subplots, suggesting that CCs did not suppress weeds throughout the maize growing season. Except for barley, CCs did not cause reductions in maize yield compared with fallow. Overall, the study suggested that with adequate winter precipitation, weed‐suppressive winter cover crop stands can be produced with just one irrigation at seeding and one supplemental irrigation, making them a viable option in water‐limited agroecosystems.