Agronomy Journal最新文献

Corn (Zea mays L.) yields have increased historically, but production concerns still exist. For decades, abnormal corn ear development symptoms have been reported. Most of these reports have not been addressed through research, perhaps due to low occurrence and challenges in replicating them. In 2016, widespread abnormal ear development (multiple ears per node, barbell-ears, and short-husk ears) issues were reported in several cornfields in the Texas Panhandle, Eastern Colorado, Nebraska, and other US Midwest states. Fields with a high frequency of abnormalities resulted in lower yields. To investigate causal factors, a field trial was established to study the effect of hybrids, environments, and planting dates on abnormal ears. The project was conducted at two Nebraska sites during the 2018, 2019, and 2020 growing seasons. Six hybrids, six environments, and four planting dates were studied. Approximately 59,200 plants were individually assessed at the dent stage (R5). Abnormal ear percentages ranged from 0% to 45% per plot, with a mean of 6.66% across all conditions. Interactions among hybrids, environments, and planting dates were documented despite the overall low incidence of abnormal ears. Grain yields ranged from 5.2 to 22.5 Mg ha⁻¹; hybrids with higher abnormal ear percentages were associated with lower yields. The main documented symptom was short-husk ears. Abnormal ears were often placed at lower heights in the plant relative to normal ears. The results presented here demonstrate the importance of studying abnormal ears and understanding the impact of planting dates and hybrid selection as potential strategies to mitigate abnormal ears.

Diversified crop rotations with no-till management are considered fundamental to sustainable agroecosystems; however, associated uncertainty in economic returns may hinder farmers’ decisions to adopt these practices. The objectives of this study were to compare economic performance (gross revenue, net revenue, and production cost) among various low-input diversified versus conventional crop rotations. The experiment was initiated in the fall of 2000 with winter wheat (Triticum aestivum L.) planting and planting of remaining crops in the spring of 2001 near Brookings, SD. Economic analysis was performed from data collected during the fifth complete 4-year crop rotational cycle (2017–2020) of six crop rotations: (1) 4-year corn (Zea mays L.)-soybean [Glycine max L. (Merr.)]-spring wheat-sunflower (Helianthus annus L.) (CSSwSf), (2) 4 year corn-soybean-spring wheat-pea (Pisum sativum L.) (CSSwP), (3) 4-year corn-pea-winter wheat-soybean (CPWwS), (4) 4-year corn-oat (Avena sativa L.)-winter wheat-soybean (COWwS), (5) 2-year corn-soybean (CS), and (6) continuous corn (CCC, treatment initiated in 2017). Corn yield in CSSwP rotation, where corn followed peas, was higher (p < 0.05) by 20%, 25%, 45%, and 89%, compared to CPWwS, CSSwSf, CS, and CCC rotations, respectively. Similarly, soybean yield following winter wheat was significantly higher by 16%–38% in COWwS and 13%–38% in CPWwS compared to CSSwP, CSSwSf, and CS. Overall, diversified crop rotations improved both corn and soybean yield and net revenue compared to 2-year CS and monoculture CCC rotations. Moreover, 4-year diversified systems, specifically COWwS, CPWwS, and CSSwP, demonstrated economic resilience by maintaining stable production costs.

Introducing integrated crop-livestock systems into row crop production promotes income diversification and potential soil health benefits through cover crop grazing on degraded soils of the southeastern United States, but effects of these practices on crop yields and soil health in Coastal Plain soils are not well established. A 4-year study was performed to evaluate the effects of grazing a multi-species winter cover crop on soil health and crop yields under mid-February, mid-March, and mid-April cattle removal dates and a non-grazed control within an annual cotton (Gossypium hirsutum L.) and peanut crop rotation (Arachis hypogaea L.). Chemical soil health indicators (soil organic carbon and permanganate oxidizable carbon), physical soil health indicators (water-stable aggregates and penetration resistance), biological soil health indicators (microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi colonization), crop yield, and cover crop biomass were evaluated. Cover crop biomass at termination was reduced by 3660, 5250, and 5610 kg ha⁻¹ for the mid-February, mid-March, and mid-April cattle removal treatments compared to the non-grazed control. No grazing treatment effects were observed for biological soil properties. Soil organic carbon was higher in the non-grazed treatment than the mid-April grazing treatment across 0- to 30-cm depth. Penetration resistance across 0- to 50-cm depth and water-stable aggregates at the 0- to 30-cm depth were both negatively impacted by increased grazing period lengths. Results from this study suggest that longer cover crop grazing periods have little effect on biological and chemical soil health indicators in the short term but can negatively impact some physical soil health indicators.

Humalite is a humic acid-rich biostimulant known for its ability to improve plant agronomic parameters and increase crop nitrogen use. Limited field research exists on Humalite effect, its application rate, and its interaction with urea, especially at reduced rates on grain agronomic parameters. Therefore, a field study was conducted from 2021 to 2023 at three Alberta sites—Battle River Research Group (BRRG), Gateway Research Organization (GRO), and St. Albert Research Station (St. Albert), in a split-plot design with four replications, three urea levels (i.e., recommended, half-recommend, and zero urea) combined with five Humalite rates (0, 56 (or 112), 224, 448, and 896 kg ha⁻¹). In 2021, the highest wheat yields were observed at half urea rates plus 224 kg ha⁻¹ at BRRG (35% yield increase), GRO (8.4% yield increase), and St. Albert (33.5% yield increase). In 2022, canola yields were unaffected by Humalite application rates. In 2023, wheat yields from half-recommended and recommended urea rates plots outperformed zero urea plots across all sites, regardless of Humalite rates. The highest wheat grain protein content values were observed at 224–448 kg ha⁻¹ of Humalite plus half-recommended or recommended urea rate. Depending on the site, the highest net revenue resulted from half urea rates plus Humalite at application rates between 112 and 448 kg ha⁻¹ in wheat, that is, optimal Humalite rate for increased profitability. Therefore, the incorporation of biostimulants such as Humalite can reduce urea use and contribute to the sustainability of wheat cropping systems.

Precision management (PM) aims to reduce inputs while increasing land productivity and economical return and enhancing cropping system resiliency to climate change. This study evaluated how climate (precipitation) and management influenced yields and soil nutrients in a dryland agricultural system. We compared an “aspirational” (ASP) system (no-till, 4-year rotation of winter wheat [Triticum aestivum L.], corn [Zea mays L.], proso millet [Panicum miliaceum L.], and fallow/flex) to a traditional “business-as-usual” (BAU) system (reduced tillage, 2-year rotation of winter wheat and fallow: W–F). Phases of each rotation were included yearly throughout the study period (2018–2022) with three replications. The ASP system incorporated PM by dividing each ASP field into three zones (high-, medium-, and low-PM) according to prior yield and topography. Nitrogen was applied at high, medium, or low application rates within those zones. Under favorable precipitation, wheat, corn, and millet yields responded to PM treatments, with yields increasing proportional to N addition. Years with low in-season precipitation had a significant reduction in wheat and corn yields (2020 and 2022) and complete millet yield failures (2020 and 2021). Low soil organic matter accumulation (0.1%–0.5%) and a reduction in soil macro- and micronutrient status suggested that soil nutrient additions are needed to prevent soil-nutrient degradation. The ASP treatment added a third crop every 4 years and did so without significantly decreasing wheat yield following fallow. The ASP management shows promise as an alternative to BAU in the Great Plains dryland production region.

Climate-smart agricultural practices, such as no-tillage (NT) and cover cropping, have been widely adopted and are anticipated to yield multiple benefits, including soil carbon sequestration, enhancing soil health, and crop yield stability. However, their influence on nitrous oxide (N₂O) emissions varies, with the potential of both increasing and decreasing N₂O emissions. Increasing N₂O emissions under these practices may potentially offset the climate mitigation benefits from increased soil carbon sequestration. We investigated N₂O emissions in response to 42 years of long-term adoption of NT and legume cover crop, under nitrogen (N) rates of 0 and 67 kg N ha⁻¹, in a continuous cotton system in the Southeastern United States. Intensive manual chamber-based measurements were conducted over two growing seasons (2021–2022 and 2022–2023). Long-term NT did not significantly affect cumulative N₂O emissions during the study period (p > 0.05). Hairy vetch cover crop-grown plots emitted two to three times more N₂O than those without cover crops in 2021–2022, with no significant effect observed in 2022–2023. Cumulative emissions in cover crop plots were greater compared to those in no cover crop plots when fertilized with 67 kg N ha⁻¹ in 2021–2022; however, this trend did not persist in 2022–2023. While interannual variability exists, our results generally suggest that long-term NT may not increase N₂O emissions, hence its adoption could enhance its broader soil health and climate benefits via soil carbon sequestration, whereas managing legume cover crop residues in N-fertilized systems is critical to mitigate N₂O emissions.

Cereal crops are frequently rotated with broadleaf crops to achieve the benefits associated with crop diversification. However, broadleaf crops often fail in Mediterranean drylands due to their lower adaptation to drought. Alternative cereal crops such as triticale (×Triticosecale Wittmack) and oat (Avena sativa L.) can help diversify drylands in the Ebro valley, dominated by barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) cultivation. A 6-year field experiment was conducted with five crop sequences under no-tillage: triticale–wheat–barley (TWB), oat–wheat–barley (OWB), fallow–wheat–barley, monocrop wheat, and monocrop barley. Wheat and barley grain yield, N use efficiency, and water use efficiency responses were evaluated, and economic analyses of the whole sequences were performed. Oat increased subsequent wheat yields by 15% and barley yields by 12% (p < 0.001) compared to monocropping. Similar water and N availability at sowing suggest additional synergies in an OWB rotation (possibly pest reduction), contributing to the yield increase of both crops. However, this rotation was less profitable than a TWB rotation (p = 0.002) due to the limited adaptation of oat to Mediterranean settings. Long fallowing lacked consistent benefits in water and N availability for subsequent crops. This practice protects farmers from economic losses in low-yielding seasons, but there is an associated opportunity cost in favorable years. The introduction of alternative cereal crops has demonstrated benefits for wheat and barley production, although greater understanding of the synergistic mechanisms involved is essential to ascertain whether resource efficiency is maintained beyond the studied timeframe.

Corn (Zea mays L.) stover demand as a forage or for an emerging bioeconomy has increased the importance of determining the long-term effects of stover removal on grain yield and soil properties. Study objectives were to evaluate grain yield, soil organic carbon (SOC), and total soil N (0–150 cm) in a 20-year, irrigated, continuous corn study, located in eastern Nebraska, under conventional tillage (CT) and no-till (NT) with variable corn stover removal rates (none, medium, and high). After 20 years, grain yield was up to 6.0% greater under NT with stover removal compared with NT and no stover removal, while yield was similar for CT in all stover removal treatments. Grain yield was similar between NT with stover removal and CT in all stover removal treatments. High stover removal rates resulted in greater SOC loss at the surface soil layers (0–15 cm and 0–30 cm) after 20 years compared with no or medium stover removal. Corn stover retention under NT resulted in the same cumulative SOC stock loss as CT or stover removal. All management practices resulted in cumulative (0–120 cm) SOC stock loss (8% decrease) that occurred in the last 10 years of the study. Total soil nitrogen stocks were maintained or increased after 20 years at the surface soil layers (0–15 cm and 0–30 cm) and were similar between NT and CT. In an irrigated continuous corn system, neither NT nor stover retention was able to maintain cumulative SOC stocks over time.

In the last decade, due to prolonged and persisting drought conditions, California initially restricted water for outdoor landscape irrigation, and subsequently offered turf removal rebates to homeowners. Nevertheless, the effects of turf removal on land surface temperature (LST) in the region have not been investigated. Temperature differences between artificial and natural turf were assessed over time across four counties in Southern California using MODIS/ASTER airborne simulator (MASTER) with a spatial resolution of 5–50 m. Moreover, airborne thermal imagery (submeter spatial resolution) was acquired over selected areas of the city of Riverside, CA, during the summers of 2018 and 2019, including neighborhoods with different income levels, and temperatures for natural turf, artificial turf, and xeriscape were recorded. Environmental and socioeconomic data were compared to the LST in different neighborhoods. Results showed that the LST difference between artificial and natural turf increases in Southern California moving from coastal region to inland. Airborne thermal imagery in Riverside confirmed that University of California artificial turf fields are irrigated during the summer to allow athletes to use the pitch. No correlation between socioeconomic factors and LST of turf and artificial turf fields (and paired differences) was found. On a city scale, natural turf lawns were consistently cooler than xeriscape and artificial turf lawns, closely mirroring mean air temperature. Socioeconomic factors do not describe LST in residential lawns, as warmest and coolest lawns regardless of vegetation are found evenly distributed among different income neighborhoods. Turfgrass removal for water conservation may have unforeseen environmental side effects.

Prohexadione calcium is a growth regulator, which manages excessive vine growth in peanut (Arachis hypogaea L.) by reducing shoot internode length. To test the effect of prohexadione calcium on peanut, a field experiment was conducted at the West Florida Research and Education Center in Jay, FL, during 2021 and 2022. The objective was to determine peanut response at different rates (untreated control, 70, 105, 140, and 175 g a.i. ha⁻¹ of prohexadione calcium). Data were collected on yield, peg strength, above- and belowground biomass, plant height, and total sound mature kernels. Additionally, return on investment for prohexadione calcium application was also calculated. Prohexadione calcium application resulted in significant reduction of peanut plant height. The application rate of 105 g a.i. ha⁻¹ resulted in significantly greater normalized difference vegetation index as compared to untreated control. Belowground, aboveground, and total biomass did not significantly differ between the 140 g a.i. ha⁻¹ rate and untreated control. However, peanut peg strength increased significantly at the 140 g a.i. ha⁻¹ treatment compared to the untreated control. Peanut yield ranged from 6.65 to 7.15 Mg ha⁻¹ among different treatments; however, the differences among treatments were not significant. Similarly, the total sound mature kernels and return on investment did not differ significantly under different prohexadione calcium treatments. Considering that peanut response to prohexadione calcium is difficult to observe in small plots, it is important to test the effect of prohexadione calcium on peanut production under on-farm large plot conditions.