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Pulse crops, including lentil (Lens culinaris Medik.) and pea (Pisum sativum L.), can improve the sustainability of Northern Great Plains cropping systems, largely through biological N fixation. Greater N fixation amounts can help producers to increase yield while decreasing N fertilizer inputs for the following crop. There may be potential to breed greater N‐fixing pulse varieties, yet little is known about varietal differences in N fixation. Nitrogen fixation of pea and lentil varieties was quantified at two sites in Montana from 2019 to 2021 using an N difference approach and the 15N natural abundance method. Riveland and CDC Richlea were frequently high N‐fixing lentil varieties, both fixing ca. 130 kg N ha−1 in the site‐year with the most favorable growing conditions. No pea variety had consistently greater N fixation than others, despite N fixation ranging from 88 to 135 kg N ha−1 in one site‐year among varieties. Nitrogen fixation by lentil had an inverse relationship with days to flowering but was not correlated with days to maturity. Nitrogen fixation by pea was positively correlated with days to maturity but was not correlated with days to flowering. Breeding lentil and pea for high N fixation by selecting high N‐fixing varieties is likely difficult, as varieties performed differently under variable environmental conditions. Breeding efforts based on traits, such as days to flowering, could be more successful. There were more positive correlations between N fixation parameters and seed yield for pea than for lentil, suggesting that breeding for greater yields could increase N fixation for pea but not lentil. Core Ideas Variation in environmental conditions strongly influenced N fixation by lentil and pea varieties. Differences in N fixation among varieties were up to 21 kg N ha−1 for lentil and 47 kg N ha−1 for pea. Two lentil varieties often fixed more N than others, while no pea varieties performed consistently well. Breeding lentil for shorter days to flower could increase N fixation, suggested by an inverse relationship. Breeding pea for greater yield or longer days to maturity could increase N fixation, suggested by positive relationships.

Cover crops during summer fallow have been rarely researched in the semiarid northern Great Plains. This study was conducted during 2012–2019 at four Montana locations and included four functional groups (Brassica family, fibrous‐rooted crops, legumes, and tap‐rooted crops). Eleven treatments included sole functional groups, a Full Mix, the Full Mix minus each functional group, pea, and chemical fallow. Wheat (Triticum aestivum L.) was grown after each cover crop year with three nitrogen (N) fertilizer rates. Cover crops were terminated with herbicide at first flower stage of pea (Pisum sativum L.) 57 to 66 days after planting. Shoot biomass averaged 2.0 Mg ha−1 over eight site‐years representative of dryland farming in Montana. Using equal overall plant densities, treatments with six species averaged 13% greater biomass than two species. Measured at termination to a 0.9‐m depth, Fallow held greater soil water than cover crop treatments, with Fallow averaging 57 mm greater than the Full Mix. Soil nitrate averaged 49 kg N ha−1 greater after Fallow than the Full Mix; the Legume treatment averaged 26 kg N ha−1 greater than the Minus Legume treatment. Wheat yield on Fallow averaged 0.85 Mg ha−1 greater than the Full Mix in 5 of 10 site‐years, mainly at the driest site‐years. The Legume treatment elevated wheat protein over the Minus Legume treatment by an average of 15 g kg−1. Cover crops grown during summer fallow reduced soil nitrate‐N, soil water, and wheat yields compared with chemical fallow, especially in the major wheat growing region of north central Montana. Core Ideas Soil improvement via cover crop growth is an uncertain trade‐off with soil water and nitrogen use. May–June rainfall best predicted cover crop biomass (Y = 757 + 12.4X; Adj. R2 = 0.72; p < 0.01). Cover crop treatments that included six crop species averaged 13% greater biomass than those with only two species. An eight‐species cover crop mix averaged 57 mm less soil water and 49 kg ha−1 less soil N compared with fallow. Wheat yield on fallow averaged 0.85 Mg ha−1 (22%) greater than cover crops for 5 of 10 site‐years.

Increasing climate aridity and drought, exacerbated by global warming, are increasing risks for western United States of America (U.S.A.) rainfed farming, and challenging producers’ capacity to maintain production and profitability. With agricultural water demand in the region exceeding limited supplies and fewer opportunities to develop new water sources, rainfed agriculture is under increasing pressure to meet the nation’s growing food demands. This study examines three major western U.S.A. rainfed crops: barley, spring wheat, and winter wheat. We analyzed the relationship between crop repurposing (the ratio of acres harvested for grain to the total planted acres) to seasonal climatic water deficit (CWD). To isolate the climate signal from economic factors, our analysis accounted for the influence of crop prices on grain harvest. We used historical climate and agricultural data between 1958 and 2020 to model crop repurposing (e.g. forage) across the observed CWD record using a fixed effect model. Our methodology is applicable for any region and incorporates regional differences in farming and economic drivers. Our results indicate that farmers are less likely to harvest barley and spring wheat for grain when the spring CWD is above average. Of the major winter wheat growing regions, only the Northern High Plains in Texas showed a trend of decreasing grain harvest during high CWD. For the majority of major crop growing regions, grain prices increased with lower levels of grain harvest. Interestingly, winter wheat repurposing is significantly higher in the southern Great Plains (∼50% harvested for grain) compared to the rest of the West (∼90%). Our results highlight that the major barley and spring wheat regions’ grain harvests are vulnerable to high spring CWD and low summer CWD, while winter wheat grain harvest is unaffected by variable CWD in most of the West.

Bioenergy carbon capture and storage (BECCS) systems can serve as decarbonization pathways for climate mitigation. Perennial grasses are a promising second‐generation lignocellulosic bioenergy feedstock for BECCS expansion, but optimizing their sustainability, productivity, and climate mitigation potential requires an evaluation of how nitrogen (N) fertilizer strategies interact with greenhouse gas (GHG) and soil organic carbon (SOC) dynamics. Furthermore, crop and fertilizer choice can affect the soil microbiome which is critical to soil organic matter turnover, nutrient cycling, and sustaining crop productivity but these feedbacks are poorly understood due to the paucity of data from certain agroecosystems. Here, we examine the climate mitigation potential and soil microbiome response to establishing two functionally different perennial grasses, switchgrass (Panicum virgatum, C4) and tall wheatgrass (Thinopyrum ponticum, C3), in a cool semi‐arid agroecosystem under two fertilizer applications, a novel cyanobacterial biofertilizer (CBF) and urea. We find that in contrast to the C4 grass, the C3 grass achieved 98% greater productivity and had a higher N use efficiency when fertilized. For both crops, the CBF produced the same biomass enhancement as urea. Non‐CO2 GHG fluxes across all treatments were low and we observed a 3‐year net loss of SOC under the C4 crop and a net gain under the C3 crop at a 0–30 cm soil depth regardless of fertilization. Finally, we detected crop‐specific changes in the soil microbiome, including an increased relative abundance of arbuscular mycorrhizal fungi under the C3, and potentially pathogenic fungi in the C4 grass. Taken together, these findings highlight the potential of CBF‐fertilized C3 crops as a second‐generation bioenergy feedstock in semi‐arid regions as a part of a climate mitigation strategy. Cyanobacteria biofertilizers are a promising sustainable alternative to synthetic nitrogen fertilizers and a potential component in climate mitigation strategies. Here, we compare the growth and environmental response of two perennial grass bioenergy candidates to a cyanobacteria biofertilizer and urea in a semi‐arid cropland. Cyanobacteria application matched urea biomass production for a cool‐season (C3) grass while the warm‐season grass (C4) had marginal growth responses to any treatment. Regardless of fertilization, soil organic carbon increased under the C3 but not the C4 grass, all treatments had low non‐CO2 greenhouse gas emissions, and crop‐specific changes were detected in the soil microbiome after three years.

Pea (Pisum sativum L.) is increasingly being rotated with wheat (Triticum aestivum L.) in Montana. Our objective was to compare economic net returns among wheat‐only and pea–wheat systems during an established 4‐yr crop rotation. The experimental design included three wheat‐only (tilled fallow–wheat, no‐till fallow–wheat, no‐till continuous wheat) and three no‐till pea–wheat (pea–wheat, pea brown manure–wheat, and pea forage–wheat) systems as main plots, and high and low available N rates as subplots. Net returns were calculated as the difference between market revenues and operation and input costs associated with machinery, seed and seed treatment, fertilizer, and pesticides. Gross returns for wheat were adjusted to reflect grain protein at “flat” and “sharp” discount/premium schedules based on historical Montana elevator schedules. Cumulative net returns were calculated for four scenarios including high and low available N rates and flat and sharp protein discount/premium schedules. Pea–wheat consistently had the greatest net returns among the six systems studied. Pea fallow–wheat systems exhibited greater economic stability across scenarios but had greater 4‐yr returns (US$287 ha−1) than fallow–wheat systems only under the low N rate and sharp protein discount schedule scenario. We concluded that pea–wheat systems can reduce net return uncertainties relative to wheat‐only systems under contrasting N fertility regimes, and variable wheat protein discount schedules in southwestern Montana. This implies that pea–wheat rotations, which protected wheat yield and/or protein levels under varying N fertility management, can reduce farmers’ exposure to annual economic variability.

Previously published data were used to examine the N economy of pulse crops typically grown on the Northern Great Plains with the goal of assessing the potential contribution of field pea (Pisum sativum L.), lentil (Lens culinaris Medik.), chickpea (Cicer arietinum L.), common bean (Phaseolus vulgaris L.), and faba bean (Vicia faba L.) to soil N accretion. Incremental changes in soil N associated with the pulse crops (i.e., the nitrogen increment, Ninc), were strongly correlated to N2 fixation and were highly variable. Data suggest that crops that can achieve relatively high levels of N2 fixation, such as faba bean, field pea, and lentil are more likely to contribute positively to the overall N economy, particularly when a cropping system is evaluated over a long term. In contrast, pulse crops that typically achieve only modest levels of N2 fixation such as desi and kabuli chickpea and common bean are more likely to be either N neutral or contribute to a soil N deficit. Because of extreme variability in levels of N2 fixation achieved, presumably reflecting variability in soil productivity as well as variations in local climate and weather, the Ninc of pulse crops likewise is highly variable. Thus, the N contribution to a subsequent crop is difficult to predict with any certainty, particularly on a yearly or short-term basis.

The need for sustainable agricultural practices to meet the food, feed, and fuel demands of a growing global population while reducing detrimental environmental impacts has driven research in multi‐faceted approaches to agricultural sustainability. Perennial cropping systems and microbial biofertilizer supplements are two emerging strategies to increase agricultural sustainability that are studied in tandem for the first time in this study. During the establishment phase of a perennial switchgrass stand in SW Montana, USA, we supplemented synthetic fertilization with a nitrogen‐fixing cyanobacterial biofertilizer (CBF) and were able to maintain aboveground crop productivity in comparison to a synthetic only (urea) fertilizer treatment. Soil chemical analysis conducted at the end of the growing season revealed that late‐season nitrogen availability in CBF‐supplemented field plots increased relative to urea‐only plots. High‐throughput sequencing of bacterial/archaeal and fungal communities suggested fine‐scale responses of the microbial community and sensitivity to fertilization among arbuscular mycorrhizal fungi, Planctomycetes, Proteobacteria, and Actinobacteria. Given their critical role in plant productivity and soil nutrient cycling, soil microbiome monitoring is vital to understand the impacts of implementation of alternative agricultural practices on soil health. The biofertilizer potential of N‐fixing cyanobacterium Anabaena cylindrica on Panicum virgatum (switchgrass) stand establishment was assessed in a semi‐arid, perennial bioenergy cropping system. Results showed biofertilizer application promoted similar plant growth as chemically fertilized P. virgatum and increased late‐season soil N‐availability without having strong effects on the soil microbial community composition or diversity. Combining perennial bioenergy crops and biofertilization could significantly improve agricultural sustainability by improving nutrient retention and maintaining microbially‐mediated ecosystem processes. These results provide a foundation for further implementation of biofertilizers in perennial bioenergy cropping systems.

To facilitate studies of the yeast proteome, we cloned 5800 open reading frames and overexpressed and purified their corresponding proteins. The proteins were printed onto slides at high spatial density to form a yeast proteome microarray and screened for their ability to interact with proteins and phospholipids. We identified many new calmodulin- and phospholipid-interacting proteins; a common potential binding motif was identified for many of the calmodulin-binding proteins. Thus, microarrays of an entire eukaryotic proteome can be prepared and screened for diverse biochemical activities. The microarrays can also be used to screen protein-drug interactions and to detect posttranslational modifications.

In the North American northern Great Plains (NGP), legumes are promising summer fallow replacement/cropping intensification options that may decrease dependence on nitrogen (N) fertilizer in small grain systems and mitigate effects of soil organic matter (SOM) losses from summer fallow. Benefits may not be realized immediately in semiarid conditions though, and longer-term effects of legumes and intensified cropping in this region are unclear, particularly in no-till systems. We compared effects of four no-till wheat (Triticum aestivum L.) cropping systems–summer fallow–wheat (F–W), continuous wheat (CW), legume green manure (pea, Pisum sativum L.)—wheat (LGM–W), and pea–wheat (P–W)—on select soil attributes in an 8-year-old rotation study, and N fertilizer effects on C and N mineralization on a duplicate soil set in a laboratory experiment. We analyzed potentially mineralizable carbon and nitrogen (PMC and PMN) and mineralization trends with a nonlinear model, microbial biomass carbon (MB-C), and wet aggregate stability (WAS). Legume-containing systems generally resulted in higher PMC, PMN, and MB-C, while intensified systems (CW and P–W) had higher WAS. Half-lives of PMC were shortest in intensified systems, and were longest in legume systems (LGM–W and P–W) for PMN. Nitrogen addition depressed C and N mineralization, particularly in CW, and generally shortened the half-life of mineralizable C. Legumes may increase long-term, no-till NGP agroecosystem resilience and sustainability by (1) increasing the available N-supply (~26–50 %) compared to wheat-only systems, thereby reducing the need for N fertilizer for subsequent crops, and (2) by potentially mitigating negative effects of SOM loss from summer fallow.