Agronomy Journal

Understanding the response to temperature, vernalization, and photoperiod provides a significant advantage for optimizing the adaptability of oat (Avena sativa) genotypes to different production areas and sowing seasons in a climate change context. For this, two experiments were carried out in the Argentinian Pampas, where nine oat genotypes were sown on six sowing dates (from June to December, <10 h to >15 h photoperiod) and three vernalization treatments (40, 20, and 0 days at 4°C). Days from emergence to flowering were evaluated and then converted to growing degree days. The adjustment of duration from emergence to flowering using an average photoperiod was performed using bilinear regressions to determine the photoperiod sensitivity (Ps), threshold (Pt), and earliness per se. Our findings showed that genotypes were insensitive to vernalization, others with minimal requirements (<480 cold hours at 4°C) while materials with high requirements were not found, indicating a reasonably constrained range of variability. Different photoperiod responses were found between the genotypes explained by differences in Ps (slopes from −310°C days h⁻¹ to −158°C days h⁻¹) and Pt. Overall, vernalization was not strictly necessary for flowering across all genotypes or sowing dates, but its fulfillment significantly accelerated developmental transitions under long‐day conditions.

Previous research on starter fertilizer application has shown significant grain yield improvement; yet the greatest responses often occur on fields below the critical soil phosphorus (P) threshold. This study aimed to (i) investigate the impacts of starter fertilizer placement on corn growth, nutrient uptake, and grain yield in P‐sufficient soils and (ii) determine whether the timing of planting influences corn response to starter fertilizer placement across different growing environments. Field experiments were conducted at three locations in eastern South Dakota from 2021 to 2023, comparing an early with a normal planting date utilizing different starter fertilizer combinations, placements, and rates. Liquid fertilizers were used with and without zinc, placed in the seed in‐furrow at a lower (IFL) and a higher (IFH) rates, 5 × 5 normal rate placement (5 × 5), a combination of IFL and 5 × 5 placement and a control treatment without starter fertilizer application, with nutrient rates 10, 15, 25, 35, and 0 kg P2O5 ha⁻¹, respectively. The planting timing did not significantly influence corn response to starter fertilizer placement across the locations. Starter fertilizer placement, relative to the control, increased early‐season growth stage by 3.2% and 2.3%, plant height by 0.75 and 3.1 cm, dry matter production by 83 kg ha⁻¹, N and P uptake by 3.1 and 0.34 kg ha⁻¹, respectively. However, these improvements did not translate into increased whole season crop physiological parameters or grain yield. Therefore, this result indicates that starter fertilizer application will not be necessary on P‐sufficient soils for yield increased in eastern South Dakota.

Turfgrass irrigation based on evaporative requirements strengthens water conservation efforts. A study was conducted from 1998 to 2000 to determine actual evapotranspiration (ETa) of warm and cool‐season turfgrasses and to develop crop coefficient (KC) values normalized for growing degree days. Predicted values of maximum ETa and KC were calculated, and data from a second study were used to validate the fitted polynomial functions. Estimated ETa differed in 1998 and 1999 and ranged from 5.42 mm day⁻¹ (Poa pratensis L. ‘Adelphi’ in 1998) to 6.69 mm day⁻¹ (Lolium perenne L. ‘Seville’ in 1999) for cool‐season turfgrasses (CS) and from 4.54 mm day⁻¹ [Buchloe dactyloides (Nutt.) Engelm. ‘Bison’ in 1999] to 5.15 mm day⁻¹ [Cynodon dactylon (L.) Pers. ‘Guymon’ in 1998] for warm‐season turfgrasses (WS). For CS, between‐year variation was greater than differences within years, but for WS, within‐year differences were greater than between years. A quadratic function was used to model the trend in KC. For CS, KC differed among years, with similar trends in 1998 and 1999. Generally, values for CS ranged from 0.76 to 0.95 and for WS from 0.68 to 0.76. We were unable to establish a clear trend that would group both CS and WS into high water use versus low water use. If a variable KC based on our models had been applied during the 3‐year period, irrigation amounts would have been reduced by approximately 10% for CS and by 15% for WS when compared to a constant KC.

Potassium (K) is essential for potato (Solanum tuberosum L.) production, influencing physiological processes, nutrient uptake, and tuber quality. This study evaluated the interactive effects of K and nitrogen (N) on potato yield and quality in Florida's sandy soils to determine optimal K application rates for maximum yield and improved N use efficiency. A 2‐year experiment was conducted in a split‐plot design with three N rates (168, 224, and 280 kg N ha⁻¹) in the main plot and six K rates (0, 112, 224, 336, 448, and 560 kg K2O ha⁻¹) in subplots in four replications in Hastings, FL. Results revealed a significant effect of seasons on the soil K availability, uptake, tuber yield, and nutrient use efficiency. The soil K levels and uptake increased with higher K application rates across all potato growth stages. Regression analysis identified optimum K rate of 425 and 535 kg K₂O ha⁻¹ for total and marketable tuber yield, respectively. In the first season, total tuber yield increased by 33% and 38% at K application rates of 336 and 560 kg K₂O ha⁻¹, respectively, compared to no K application. Tuber specific gravity was not affected by K rates, while the higher K application rates increased the N use efficiency and decreased benefit‐cost ratio. The study concludes that K application rates above 425 kg K₂O ha⁻¹ maximize potato tuber yield and enhance N efficiency, supporting the revision of K recommendations in sandy soils based on low K status.

Crop evapotranspiration (ETc) is a critical factor for understanding water demand in agricultural systems, influencing irrigation scheduling and water resource management. Identifying the meteorological factors influencing ETc is crucial for predicting variations in water needs and optimizing irrigation plans. Traditional correlation analysis methods, such as Pearson correlation, often fail to capture the time‐frequency variations in ETc, which limits their ability to effectively identify the primary influencing factors. This study integrates the Penman–Monteith model, Pearson correlation analysis, wavelet analysis, and vector projection length calculation method to propose a comprehensive approach for identifying primary and secondary meteorological influences on ETc from a time‐frequency perspective. Using rice (Oryza sativa) in the Gaoyou Irrigation District of Jiangsu Province, China, as a case study, the research examines seven meteorological factors—including air temperature, relative humidity, rainfall, and sunshine duration—along with four circulation indices, such as the East Asian Summer Monsoon index and ENSO index, from 1980 to 2021. The results indicate that sunshine duration and relative humidity are significant factors affecting the high‐frequency and low‐frequency signal components of local rice ETc, respectively. Additionally, other factors, such as minimum temperature, show strong correlations with ETc signals within specific frequency bands, positioning them as secondary influencing factors. This research presents a versatile framework that can be extended to other areas of hydrometeorology and beyond.

In Mexico, sesame (Sesamum indicum L.) is cultivated in rainfed environments with high temperatures and erratic precipitation. In these environments, there is low productivity due to the low availability of improved varieties; however, there is genetic diversity that can be used in programs for crop improvement. The objectives were to evaluate the grain yield per hectare (GY), variables associated with it, and the genotype × environment interaction (G × EI) in 50 sesame genotypes in four environments; these environments were integrated by Iguala and Zicapa in the spring–summer cycles 2021 and 2022 in Guerrero, Mexico; an alpha lattice design with three repetitions was used. The following analyses were conducted: combined analysis of variance, multivariate additive main effects and multiplicative interaction (AMMI), stability analysis, and Biplot G + G × EI. The combined analysis detected significant differences (p ≤ 0.01) for environment, genotype, and G × EI in every variable. The AMMI analysis showed greater variation in environment; the genotype component indicated 58.3% of variation of the GY and 24.8% of the G × EI. The coefficient of regression varied from 0.03 to 2.45, and the regression deviation was 0.03–0.26, with this indicating that the genotype had different responses to the environments. The Biplot G + G × EI with two components explained 80.75% of the variation in GY. The models and parameters used indicated that the Los_Hornos genotype (792.31 kg·ha⁻¹) presented a better stability and GY classification, higher than the general average (569.9 kg·ha⁻¹) and the improved control Calentana (591.85 kg·ha⁻¹). Therefore, this genotype can have a significant impact on the genetic gain of GY for future sesame improvement programs.

Direct‐seeded rice (Oryza sativa) cultivation (DSR) is gradually replacing transplanted rice cultivation (TPR) across tropical Asia owing to labor shortages. However, the yields in DSR are lower than those in TPR under current farmer practices (FPs). It would be useful to introduce best management practices (BMPs), holistic technology packages prepared by researchers and extension staff, to improve DSR yield. We aimed at quantifying the effect of BMPs application on the on‐farm yield, input factors (labor requirements and production costs), and cost–benefit performance of DSR and comparing it with the results of TPR. On‐farm trials were conducted for 2 years in Timor‐Leste (East Timor) and categorized farmers into a 2 × 2 experimental design: farmers who used FPs in DSR, BMPs in DSR, FPs in TPR, or BMPs in TPR. There were no significant yield differences between DSR and TPR under BMPs (3.5 vs. 3.6 t ha⁻¹), but DSR produced a 20% lower yield than TPR under FPs (2.4 vs. 3.0 t ha⁻¹). Yield increases due to BMPs were greater in DSR (+46%) than in TPR (+20%). The benefit–cost ratio of BMPs in DSR was 21% higher than that of BMPs in TPR (1.48 vs. 1.22). DSR farmers can achieve yields similar to those of TPR farmers by applying BMPs, with less labor and lower production costs, even where subsistence farming prevails. The effects of BMPs on DSR and TPR in this study suggest that the BMPs could improve land and labor productivities through DSR in tropical agricultural development programs.

Planting date significantly impacts soybean (Glycine max L.) production in the Upper Midwest. Farmers often plant as early as possible, assuming higher risks and costs, to maximize yield potential. However, in drought‐prone, low‐productivity areas, the benefits of early planting, which are attributed to radiation utilization, could be offset by water stress. This study evaluated the effects of planting date and cultivar maturity on yield across environments with varying attainable productivity levels. Field experiments were conducted over 25 consecutive seasons (1999–2023) in Lamberton, Southwest MN, encompassing a broad range of productivity. An attainable productivity index that was strongly linked to precipitation availability was used to classify environments. In high‐attainable productivity environments, early planting with full‐season cultivars resulted in significant yield advantages, with delays reducing yield by up to 0.3% per day. Conversely, in low‐productivity environments, planting delays until late May did not reduce yield and, in extreme cases, yielded positive responses. Across all the environments, planting beyond the end of May consistently led to steep yield declines above 1% per day, regardless of resource availability or maturity. These findings highlighted that early planting with full‐season cultivars was optimal for high‐productivity environments but provided no clear yield advantage in drought‐prone, low‐productivity environments, where the risks and costs may not be justified. The results could offer guidance for tailoring planting date within heterogeneous fields.

Mungbean [Vigna radiata (L.) R. Wilczek var. radiata] is a potential crop for an inexpensive supplier of plant‐based protein for promoting food security. One of the causes of low mungbean production is pod shattering during pod maturing or harvesting. Currently, there is limited knowledge regarding the effects of genotype and genotype × environment (G × E) interaction on pod‐shattering resistance in mungbean. This study aimed to analyze the effect of G × E and to identify mungbean genotypes that had stability on pod‐shattering resistance and high yield. The study was conducted across two locations (Malang and Probolinggo, East Java, Indonesia) and two seasons (Dry Season 1, February to May 2023, and Dry Season 2, June to August 2023). Forty mungbean genotypes were evaluated for morpho‐agronomic traits (three qualitative and 16 quantitative traits) and pod‐shattering resistance (represented by the proportion of non‐shattering pods). There was a significant interaction effect of G × E for non‐shattering pod and yield. Genotypes G8 (MLGV 0377), G10 (MLGV 0371), G21 (MLGV 1052), G31 (Murai), and G36 (Vima 3) were identified as potential due to their stable resistance to pod shattering as well as high and stable yields based on several stability parameters, including linear regression coefficient (bi) = 1. These five genotypes belong to the resistant category, exhibiting a non‐shattering pod percentage of 91%–99%. No correlation was observed between qualitative traits and pod shattering, while for quantitative traits, a significant positive correlation (r = 0.35, p < 0.05) was found between pod width and non‐shattering pod. Our findings indicate the possibility of breeding stable pod‐shattering‐resistant genotypes with high yield, which would pave the way to advancing near‐future mungbean breeding programs.

Potatoes (Solanum tuberosum L.) have been shown in previous studies to respond to P fertilizer on high‐P testing soils. Response to P under these conditions may be due in part to their shallow root systems and poor associations with mycorrhizal fungi due to the use of fumigation to control soilborne diseases. This study evaluated the effects of P placement and microbial inoculation on tuber yield and P recovery in high‐P soil. A field study with a split–split‐plot randomized complete block design was conducted over 2 years, with whole plots defined by fumigation treatment (no fumigant or metam sodium) and subplots defined by cultivar (Ivory Russet or Russet Burbank). Each subplot was divided into seven sub‐subplots by P treatment. Four treatments were used to evaluate banded versus broadcast P placement at 37 and 73 kg P ha⁻¹ without inoculant. Four treatments were used to evaluate the effect of broadcast P at 0 and 73 kg P ha⁻¹ with or without an inoculant. At equivalent P rates, banded P placement produced 4.8% greater tuber yield, 4.8% greater P uptake, and 5.0% greater P recovery efficiency (PRE) than broadcast placement. However, microbial inoculation had no effect on tuber yield, P uptake, or PRE with or without fumigation. High soil P or control of foliar fungi may have inhibited mycorrhizae. Overall, at equivalent P rates, banded P placement increased tuber yield even under high soil P conditions, but inoculation with arbuscular mycorrhizal fungi and other beneficial microbes had no effect.

Soil is one of the most complex microbial environments on earth, providing many ecosystem services to benefit humankind. Many of the services associated with soil microorganisms are particularly important to the agricultural industry as these improve crop stress tolerance, nutrition, and yield. However, conventional agricultural practices that use excessive chemical inputs, tillage, and monocropping have diminished the soil biosphere and lessened the ecosystem services that microbes are able to provide. Cover cropping is one of the key principles underpinning conservation agriculture systems. Despite it being relatively well‐known that cover cropping has a beneficial impact on the overall abundance and community structure of soil microbes, the effects on specific microbial structures and their functions are vastly under‐researched. In fact, some fungal structures investigated in this study have never been examined under cover cropping systems before. Therefore, soil samples were taken from five cover cropped and five conventionally managed fields growing spring bean (Phaseolus vulgaris) in Kent, UK, and the abundance of seven key mycorrhizal and endophytic fungal structures were identified. Cover cropping was associated with a significantly higher abundance of hyphae, arbuscules, vesicles, moniliform hyphae, and microsclerotia, but not spores or chlamydospores. Since these structures are known to be associated with nutrient exchange, overwintering and long‐term survival, energy storage, and branching and inoculation, cover cropping practices are likely to improve the functioning of mycorrhizal and endophytic fungi.

Previous studies indicate reduced‐lignin (RL) alfalfa (Medicago sativa L.) cultivars as a more digestible livestock feed option with minimal reductions in biomass than conventional alfalfa cultivars at the same growth stage, allowing for harvest flexibility. However, these findings are derived from environments with adequate moisture. Thus, RL performance in water‐limited environments, such as the US's Central Great Plains (CGP), is unknown. Our objective was to compare the 54HVX41 cultivar's (RL) season‐long biomass and nutritive value against three reference alfalfa cultivars (54VR10, DKA44‐16RR, and WL 356 HQ.RR) at different harvest intervals (i.e., 28, 35, and 48 days) at three locations for two seasons in the CGP. In locations that received adequate annual rainfall (near Lahoma, OK), RL alfalfa had similar or lower season‐long biomass (p = 0.02), acid detergent lignin (ADL) concentration (p > 0.01), greater neutral detergent fiber digestibility 30 h (p < 0.01), and in vitro dry matter digestibility 48 h (IVTDMD 48 h) than the reference cultivars (p > 0.01). Nevertheless, in water‐limited environments (near Hutchinson, KS, and Stillwater, OK), the RL had similar season‐long biomass, ADL, and IVTDMD 48 h concentrations to the reference cultivars. Further research is needed to validate our interpretation, as only one RL alfalfa cultivar was evaluated in water‐deficit environments.

A field study was established at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center in 2020 with the following objectives: (1) Assess the performance of alfalfa–grass mixtures under reduced irrigation. (2) Identify the best grass species and optimum seeding ratio of alfalfa–grass mixtures for improved productivity and nutritive value under full and deficit irrigations; (3) Compare the net economic return from different seeding ratios of alfalfa–grass mixtures under full and deficit irrigations. Treatments included monocrop alfalfa, 75–25 ratio, 50–50 mixed row planting, and 50–50 alternate row planting of alfalfa with each of three perennial cool‐season grasses (orchardgrass, tall fescue, and meadow bromegrass) under full and deficit irrigation. Under full irrigation, 75–25 mixture with tall fescue produced the highest 2‐year total forage dry matter, while alternate row planting of alfalfa and orchardgrass produced the highest under deficit irrigation. Deficit irrigation affected forage dry matter yield negatively. Economic analysis revealed that a 75–25 mixture of alfalfa and tall fescue under full irrigation produced the highest net present value (NPV). Although deficit irrigation reduced costs, that did not result in higher NPV than full irrigation. However, alternate row planting with orchardgrass under deficit irrigation produced an NPVsimilar to the treatments under full irrigation.

Grid‐based soil sampling captures within‐field fertility variability, enabling site‐specific lime and fertilizer management but at a high cost. This study grid‐sampled 20 corn (Zea mays L.) fields in New York to (1) document spatial variability in soil series, pH, soil test phosphorus (P), and potassium (K); (2) assess the impact of grid size (0.2, 0.4, 1.0 ha/grid) on field‐based lime, P, and K recommendations compared to whole‐field sampling for corn with and without alfalfa (Medicago sativa L.) in the rotation; and (3) derive guidance for soil sampling beyond the initial grid‐based sampling event. Soil pH was measured using a 1:1 soil‐to‐water mixture, while P and K were extracted or converted to Morgan equivalents. Soil pH ranged from 6.2 to 7.4, while P and K varied from 3 to 177 mg P/kg and 22 to 213 mg K/kg, respectively. Grid‐based management led to higher recommended lime rates, especially for fields in alfalfa rotations. For P, grid‐based decision‐making increased the recommended amount of fertilizer for many fields. For K, several fields showed potential fertilizer savings. In most fields requiring lime applications, the amount recommended increased with grid size, whereas for P and K, smaller grid sizes resulted in higher recommendations. Grid‐based soil measurements were converted to soil test‐based management zones, providing both a transition from regular grid sampling in the initial year to more cost‐effective zone‐based sampling in future years, and a means to homogenize the field with targeted lime and fertilizer management.

Annual bluegrass (Poa annua) golf course putting greens are prone to winterkill in northern regions. Therefore, a 2‐year field trial was conducted to investigate whether mowing height increases of annual bluegrass putting greens starting in late summer could improve winter recovery. Field plots in East Lansing, MI, were mown at a height of 3.17 mm (control), or the mowing height was raised gradually to a maximum height of 3.81, 4.44, and 5.08 mm. The changes in mowing regimes started in early September for both years. Normalized vegetative difference index (NDVI), leaf area index (LAI), and chlorophyll index (CHL) were measured during the fall and spring of 2021/2022 and 2022/2023. In March of both years, turfgrass plugs (10.16‐cm diameter) were extracted from each plot and were transferred to a low‐temperature growth chamber and encased in ice for 0 (no ice encasement), 10, 20, or 40 days. After ice encasement, percent green cover was determined and total nonstructural carbohydrate (TNC) analyzed for crowns, leaves, and roots. Fall NDVI, LAI, and CHL values were positively correlated with higher mowing heights, particularly 5.08 mm. Increasing duration of ice encasement reduced TNC in leaf, crown, and root tissues, but mowing height had no effect on TNC. Overall, increasing mowing height in fall may enhance annual bluegrass's spring recovery; however, additional research is needed to explore optimal mowing heights and timings.

Drought stress is a critical factor that limits the growth, yield, and related traits of durum wheat (Triticum turgidum L. var. durum). Thus, to identify superior drought‐tolerant genotypes, a comprehensive study was carried out through rainout shelter and field experiments during the 2020–2021 and 2022–2023 growing seasons. The goal was to select genotypes that exhibit enhanced drought resilience based on key morphophysiological traits. In the preliminary phase, 100 genotypes were exposed to two water regimes: drought‐stressed and well‐watered conditions. From this pool, 12 promising genotypes were shortlisted for further evaluation in both pot experiments and natural drought‐prone environments. Various traits, including leaf water status, leaf gas exchange parameters, morphological characteristics, and agronomic performance, were measured. The results highlighted significant genetic variation among the genotypes for traits such as relative water content (RWC), excised leaf water loss (ELWL), and chlorophyll content. Significant differences were also observed from transpiration rate (E), photosynthetic rate, stomatal conductance (gsw), intercellular CO2 concentration (Ci), boundary layer conductance, normalized difference vegetation index, leaf angle, and leaf rolling. Among the tested genotypes, DW183123 consistently outperformed others in both drought‐stressed and well‐watered conditions, demonstrating superior performance in pot and field trials. Under drought stress, it maintained higher RWC, Ci, E, and gsw, and low ELWL in drought stress conditions, which were identified as having a greater potential to maintain water balance in their leaves. Moreover, it displayed tighter inward leaf rolling with erect leaves compared to susceptible genotypes, which exhibited loose rolling. Therefore, these findings suggest that DW183123 is a promising candidate for future wheat breeding programs aimed at enhancing drought tolerance in durum wheat varieties.

Intercropping, the growing of more than one crop at the same time within the same land area, could be a sustainable method of crop production in semiarid regions, which could increase biodiversity, and productivity and quality of crops compared to monocultures. This may be of significance under limited N, such as in organic agriculture, and could be an alternative to green manure. An organic study was conducted in the semiarid Canadian Prairie in drier than average years (2017–2018) to determine if intercropping legumes with non‐legumes could reduce weeds and increase grain yield and quality of crops at different seeding rate ratios. Intercrops examined were lentil (Lens culinaris Medik.)–yellow mustard (Sinapis alba L.), and field pea (Pisum sativum L.)–oat (Avena sativa L.), at three seeding rate ratios, and their respective monocultures. Weed density was lower in the pea–oat intercrop than the pea monoculture, while weed biomass was lower in the lentil–mustard intercrop than the lentil monoculture. Legumes, when intercropped even at monoculture ratios, had lower aboveground biomass and grain yield than their monocultures, with pea showing higher tolerance than lentil to competition with its companion. Total biomass and grain yield were accounted for mostly by the non‐legumes, which performed better than expected based on their seeding ratios. Mustard grown with lentil appeared to be more competitive than oat grown with pea. Grain weight of oat was higher in all intercrops with pea than in its monoculture, while grain protein of pea was higher when intercropped with oat than in its monoculture.

Organic crop production relies mostly on legumes for N input. Intercropping of organic legumes with more competitive crops might provide an alternative to the poor weed suppression and disease susceptibility of legumes. It might also be expected that such intercropping could be of benefit to crops grown in the subsequent year through increased N from the preceding intercropped legume, and lower weed growth due to the more competitive companion. The objective of this study, conducted under drier than average conditions in a semiarid region of the Canadian Prairies, was to determine how organic intercrops of legumes with a cereal or oilseed at different ratios would affect soil nutrients the next spring, weed levels, and the productivity and quality of the following durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.]. Results from 2018 to 2019 showed that intercropping had a negligible impact on Olsen P and extractable K. Soil NO3‐N (>15‐cm deep) was lowest following the lentil (Lens culinaris Medik.)–mustard (Sinapis alba L.) intercrops and mustard monoculture, which was reflected in lower growth of the durum wheat. Conversely, some of the pea (Pisum sativum L.)–oat (Avena sativa L.) intercrops and the oat and all legume monocultures resulted in higher durum wheat biomass and grain yield, with their highest values observed after the checks summerfallow and forage pea manure. Weeds tended to have lower densities after the intercrops than the grain legume monocultures. Nutrient concentration in plant tissue suggested that weeds could be a greater source of soil nutrients than crops.

Research is lacking on wheat (Triticum aestivum L.) mineral nutrient uptake at broad scales, accounting for environmental variation, which is needed to effectively manage and model nutrient dynamics of wheat cropping systems. Therefore, our primary research objectives were to (1) provide analysis and estimation tools characterizing wheat nutrient (N, P, K, Mg, Ca, S, Mn, Fe, Zn, Cu) uptake in grain and the whole crop at farm and regional scales and (2) evaluate nutrient harvest indices (NutHIs)—nutrients deposited in grain relative to total aboveground uptake—as an indicator of crop nutrient relations/economies. There were clear linear relationships between grain yield and nutrient uptakes in grain and the whole crop. Functions describing the nature and error of these relationships are presented, along with more flexible estimation approaches. Median NutHIs approximated averages synthesized from recent studies and generally exceeded those from older studies, consistent with evidence that NutHIs have increased with wheat improvement. The NutHIs, except ZnHI, were generally positively associated with grain harvest index and not related to yield. Given that grain mineral density, an indicator of nutritional value, has declined over time, making ongoing progress in simultaneously improving grain yield and mineral density may depend on selection for increased crop nutrient uptake and partitioning to grain. This study also provided corroborative evidence that the modern wheat classes do not differ in grain mineral density. In summary, this research provides valuable data and tools useful for sustainable nutrient management and provides insights into the nutrient economy and nutritional value of modern wheat.

Over the past century, numerous studies have addressed the physiology and genetics of biological nitrogen fixation (BNF) in legumes—targeting improvements through screening of existing germplasm, hybridization, and mutagenesis. Although these efforts have not been successful in commercializing grain pea (Pisum sativum) varieties with enhanced BNF, they offer promising avenues for improving pea BNF for forage and cover crop (CC) cultivation. To examine this approach, we tested the performance of a panel of 20 pea lines derived from crosses between high‐yielding pea cultivars and two supernodulated pea mutants, Frisson‐Sym29 and Rondo‐nod3. The pea lines, parents, and mutant checks were trialed during the 2020 and 2021 growing seasons in Chico, CA, under rainfed conditions. Nodulation, the percent of nitrogen derived from the atmosphere (%Ndfa), biomass and nitrogen accumulation, and days to flowering of progenies were compared to their parent varieties and mutant donors. Overall, tested materials performed similarly in both study years. The pea produced an average dry biomass of 1694 kg in 2020 and 1964 kg in 2021 while accumulating 53.3 kg N ha⁻¹ in 2020 and 57.1 kg N ha⁻¹ in 2021. The materials produced up to 120 and 126 nodules plant⁻¹, weighing 126 and 217 mg plant⁻¹, in 2020 and 2021, respectively. Genotypic variations for agronomic and N‐fixation traits were mainly associated with variations of parent cultivars and mutants. This study suggests that screening nodulation and aboveground and belowground biomass at pre‐commercial breeding stages might yield effective CC varieties compared to screening solely for %Ndfa and grain yield.

Coarse‐textured soils in central Minnesota cultivated with corn (Zea mays L.) and soybean (Glycine max L.) exhibit good productivity, however, are vulnerable to nitrate‐N leaching losses. In such circumstances, winter rye (Secale cereale L.) as a cover crop may reduce nitrate‐N leaching by scavenging soil nitrogen (N) in late‐fall and early‐spring fallow period. The Environmental Policy Integrated Climate (EPIC) model was used for decadal‐scale (2010–2020) simulation of yield/biomass and nitrate‐N leaching in corn– (C–C) and corn–soybean/soybean–corn (C–Sb/Sb–C) rotations, with and without winter rye, under different fertilizer N rates applied to corn (0, 100, 200, 250, and 300 kg ha⁻¹) on irrigated coarse‐textured soils in central Minnesota. Model efficiency calculated based on Nash–Sutcliffe coefficient, relative root mean square error, and R² statistics indicate that EPIC assessment for calibration and validation treatments was excellent‐good for corn/soybean yield, and good‐satisfactory for rye biomass and NO3‐N leaching losses. Results indicate that N fertilizer rates up to 250 kg N ha⁻¹ applied to corn had a positive impact on rye biomass; however, large crop‐rotation and climate‐induced variations were observed. Annual nitrate‐N leaching losses at maximum return to nitrogen rates at a 0.05 N price to crop value ratio for corn under C–C (250 kg N ha⁻¹) and C–Sb/Sb–C (200 kg N ha⁻¹) with no‐rye averaged 61.5, 47.4, and 41.8 kg ha⁻¹, while grain yield averaged 12.5, 12.3, and 4.0 t ha⁻¹ for corn (C–C), corn (C–Sb/Sb–C), and soybean (C–Sb/Sb–C), respectively. Planting rye under these rotations gave annual average reductions in nitrate‐N losses relative to corresponding no‐rye treatments of 2.9 (4.7%), 3.4 (7.3%), and 6.5 kg ha⁻¹ (15.6%), with rye N uptake of 10.3, 12.1, and 33.5 kg ha⁻¹; and rye biomass production of 0.61, 0.74, and 2.0 t ha⁻¹, respectively. EPIC assessment indicates that winter rye as cover crop did not negatively impact the subsequent corn/soybean yield and proved to be an effective strategy for reducing nitrate‐N losses, particularly following the soybean crop.

Soybean [Glycine max (L.) Merr.] after winter wheat (Triticum aestivum L.) is the most common double‐cropping system in the United States, driven by the desire for increased cash flow and profits and bolstering global food security. Despite its popularity, double‐cropping often results in a lower soybean yield compared to full‐season systems, attributed to various factors. Maintaining wheat stubble height ≤30 cm during harvesting and planting soybean in between wheat rows minimizes some negative effects of wheat residue. Planting double‐crop soybean immediately after wheat harvest is crucial, as late planting is the primary factor of diminished double‐crop yield. Late planting results in a shorter soybean growing season, limiting the time available to develop an optimal leaf area index (LAI). Harvesting wheat at high moisture or planting early‐maturing wheat cultivars with comparable yield potential can facilitate 7–10 days earlier soybean planting. Employing narrow rows (19 cm) during double‐crop soybean planting ensures rapid attainment of optimum LAI (3.5–4.0) by the pod set stage, maximizing solar radiation interception and canopy photosynthesis. A 16 kg ha⁻¹ starter N may enhance early vegetative growth, expediting optimal LAI achievement. Indeterminate soybean may be more appropriate for double‐crop due to fewer branching habits, which reduces competition in narrow rows compared to determinate counterparts. Double‐crop soybean in narrow rows requires higher seeding rates than full‐season to maximize yield by optimizing LAI expeditiously. Additionally, double‐crop soybean is more vulnerable to drought and insect–pest infestation or defoliation than full‐season system. Therefore, managing double‐crop soybean with the same diligence as full‐season is imperative to maximize yield and profitability.

Nitrogen (N) management is crucial to increase winter wheat production. Improved prediction of the economic optimal N rates (EONR) for winter wheat could increase N use efficiency and farmers' profits. However, characterization of the variability in the EONR and the performance of existing dynamic and static N recommendation models have been limited. The objectives were (i) to characterize winter wheat yield and protein content response to N rate and timing and (ii) to evaluate the performance of static and dynamic N recommendation models. Nine experiments across 2 years were conducted in eastern Nebraska to evaluate N rate recommendation models and N application timing. Dynamic models included Oklahoma State University, Holland and Schepers, and Kansas State University remote sensing‐based N recommendations. Static N recommendation models included empirical equations from the University of Nebraska–Lincoln and Kansas State University. The EONR ranged across site‐years from 57 to 150 kg N ha⁻¹, yield at the EONR from 3.33 to 7.51 Mg ha⁻¹, and protein at the EONR from 11.1% to 16.4%. There was no significant effect of the timing of N application on grain yield and protein content. Dynamic N recommendations performed better than static models based on an average difference from the observed EONR (±14.8 kg N ha⁻¹ and 46.0 ± 83 kg N ha⁻¹, respectively). Further testing of N winter wheat recommendation models is needed to better inform winter wheat growers about N management and fine‐tuned N recommendations to current management practices.

Cover cropping in the fallow phase of winter wheat (Triticum aestivum L.)–fallow systems of the semiarid Pacific Northwest has been identified as an opportunity to build resilience and enhance farm profitability. Nine fall‐ and spring‐sown cover crops (CCs) grown during the traditional fallow period were evaluated at sites in the low and intermediate precipitation zones of the region in a 2‐year study (2021 and 2022). The fall‐sown CCs included winter pea (Pisum sativum L.), winter lentil (Lens culinaris Medik.), and fall species mix; and the spring‐sown CCs included common vetch, yellow mustard, lacy phacelia, tillage radish (Raphanus sativus L.), spring barley (Hordeum vulgare L.), and a spring species mix. CCs were evaluated for biomass production and impacts on soil water and weeds. CC growth was dependent on location, year, planting timing, and CC species. Fall‐sown CCs generally produced more biomass than spring‐sown CCs across site‐years, with winter peas and the fall species mix being most productive. Following a year of greater than average precipitation, no negative effects of CCs on fall soil moisture were observed at the intermediate precipitation site, while fall‐sown CCs reduced soil moisture at the low precipitation site. The suppressive effect of CCs on weeds ranged from null to moderate, depending on site, year, and CC seeding time. Fall‐sown CCs more consistently suppressed weeds than spring‐sown CCs. Additionally, fall‐sown CCs were terminated in the spring before weeds set viable seeds, saving a herbicide application and reducing herbicide pressure without exacerbating future weed issues. Overall, select fall‐sown CCs showed promise to enhance ecosystem services during the traditional fallow period.

Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] account for much of the arable land in the Upper US Midwest during the summer. Land is left fallow in late autumn after harvest through early spring leaving valuable growing degree days unused. Temporal intensification is a concept that considers planting crops such as winter camelina (Camelina sativa L.) during these fallow periods. Winter camelina is a freeze‐hardy winter annual oilseed that can provide an economic benefit to farmers the following spring. However, there are significant agronomic and economic trade‐offs associated with integrating camelina into the corn–soybean rotation. The objectives were to assess the yield potential and seed quality of a corn–camelina–soybean rotation using (1) a range of corn hybrid maturities, (2) corn stover presence or absence, and (3) calculate the economic trade‐offs compared with a typical corn–soybean rotation. This study was conducted over the 2019 and 2020 growing seasons at two locations in Minnesota. Corn and soybean seed yield was maximized in treatments where camelina performed poorly and vice versa. Late corn harvest and stover presence had a negative effect on camelina establishment and yield but were favorable to soybean production. Based on both the agronomic and economic analyses for the aggregated cropping system, treatments that began with 90‐ and 95‐day relatively mature corn hybrids performed equally well, regardless of stover presence. This indicates there are multiple options to move forward with a corn–camelina–soybean cropping rotation.