Agrosystems, Geosciences & Environment最新文献

Effective nitrogen management is vital for maximizing yield and maintaining soil health in Basmati rice cultivation. A 2-year field study (2023–2024) was carried out to investigate the effects of integrated nitrogen management on yield traits, grain quality, and nitrogen use efficiency (NUE) in three Basmati rice (Oryza sativa L.) cultivars: Pusa Basmati 1718, Pusa Basmati 1847, and Pusa Basmati 1886. The experiment employed a split-plot design, with cultivars as main plots and six nitrogen treatments in sub-plots, incorporating prilled urea, foliar nano urea, and green manuring in various combinations. Pusa Basmati 1847 consistently showed superior performance in panicle length, grain count, 1000-grain weight, and overall yield. Among nitrogen regimes, the treatment comprising 75% prilled urea combined with a single nano urea spray and green manuring achieved the highest grain yield (5.29 t ha⁻¹), biological yield (11.97 t ha⁻¹), and NUE (32.33%). Integrated nitrogen approaches significantly improved nitrogen accumulation in both grain and straw without depleting residual soil nitrogen. These findings highlight the potential of combining conventional fertilizers with nano and organic sources to enhance productivity, grain quality, and nitrogen use efficiency in aromatic rice systems.

Agronomic practices for good crop performance vary with variety and growing conditions. A split-plot experiment was conducted in the dry season in southwestern Ethiopia to determine growth, yield component, and yield responses of medium- and late-maturing hybrid maize (Zea mays L.) varieties (BH-546 and BH-661, respectively) to different plant densities (39,216, 44,444, 47,059, 51,282, 53,333, 58,824, 61,538, 66,667, and 76,923 plants ha⁻¹) and to optimize the plant density for offseason hybrid maize production in the hot-submoist tropical environment of the study area. Both variety and plant density significantly affected most growth traits and yield components considered, while their interaction significantly affected grain yield and harvest index. The late-maturing variety provided higher growth and yield components than the medium-maturing variety. The higher plant density (66,667 and 76,923 plants ha⁻¹) showed a higher leaf area index and biomass yield followed by 53,333 plants ha⁻¹. However, the higher plant density (76,923 plants ha⁻¹) produced a smaller stalk diameter, leaf area, cobs, and 1000-grain weight than the other plant densities. The late-maturing variety planted at 66,667 plants ha⁻¹ and the medium-maturing variety planted at 53,333 plants ha⁻¹ produced a higher grain yield with a higher economic return than the other variety–plant density combinations, suggesting that these plant densities can be used for hybrid maize production under irrigation system in the offseason in the study area. This study also pinpointed that the optimum plant density for offseason maize production differs from that is recommended for the rainy season (44,444 plants ha⁻¹).

High-protein wheat (Triticum aestivum L.) grain is useful for bread flour, and normalized difference vegetation index (NDVI) can be useful in predicting crop yields and assessing overall crop health in response to a wide variety of management systems. However, protein and NDVI responses to nitrogen rates in systems containing cover crops have been understudied in spring wheat. Protein, grain yield, and NDVI measurements were collected during the spring wheat phase of spring wheat–pea (Pisum Sativum L.)/cover crop rotations in different plots in 2018 and 2019 at the Northern Great Plains Research Laboratory, Mandan, ND. Grain protein concentration increased with nitrogen (N) rate, but not every level of N rate was significantly different. This result suggests that preceding pea then cover crop mixture can slightly reduce the nitrogen fertilizer requirements of subsequent spring wheat. Spring wheat NDVI did not significantly respond to categorical nitrogen rates, but continuous N rate had a small positive effect. Adding NDVI heterogeneity (as measured by the nugget:sill ratio) improved peak NDVI-based spring wheat grain yield predictions at the relatively small scales that were measured.

Soil is a fundamental resource for plant growth and ecosystem sustainability, yet limited site-specific soil information has hindered optimal sugarcane (Saccharum officinarum L.) production in the Arjo-Dhidhesa Estate Sugar Factory Development Project area, Oromia, Ethiopia. This study aimed to characterize and classify the soils across 28,092 ha to inform sustainable land management and enhance sugarcane productivity. A detailed field survey was conducted, including 90 auger observations and the selection of representative pedons, following Food and Agriculture Organization soil description guidelines. Physical and chemical properties such as texture, bulk density, pH, organic carbon, and exchangeable bases were analyzed. The results revealed considerable variability in soil properties among pedons. Most exhibited clay to heavy clay textures favorable for water and nutrient retention, while Pedon A-5 showed sandy clay loam, suggesting better drainage. Variations in bulk density, porosity, and water-holding capacity reflected differences in root penetration and moisture availability. Soil pH ranged from slightly acidic to neutral, and several pedons demonstrated high organic carbon, cation exchange capacity, and exchangeable calcium indicative of good fertility. These findings underscore the importance of site-specific soil data in guiding sugarcane management. The diversity of soil types across the estate necessitates tailored strategies to enhance productivity and support sustainable agriculture. This study provides a foundation for implementing targeted soil management practices to improve crop yields and long-term soil health in the Arjo-Dhidhesa Estate Sugar Factory.

Summer fallow practices are of increased interest in semi-arid irrigated areas of the western United States as a means to replenish water resources. Understanding of cereal residue decomposition in these conditions is limited, and data are needed to develop guidance. Research was conducted from 2018 to 2020 in Aberdeen, ID. Residue decomposition bag studies assessed crop type (barley [Hordeum vulgare L.], corn [Zea mays L.], hard red wheat [Triticum aestivum L.; HRW], and soft white wheat [SWW]), tillage (surface and incorporated), and supplemental fertilizer-N rates (0, 56, and 112 kg N ha⁻¹) collected after application (spring, summer, and fall). Barley, corn, HRW, and SWW carbon:nitrogen (C:N) ratios were 74, 62, 105, and 87, respectively. Crop type and tillage affected residue decomposition, but fertilizer-N had no impact. Decomposition was greatest from post-harvest to spring for incorporated corn (37%) and least for surface barley, HRW, and SWW (21%). At the fall sampling, patterns were largely the same with minor changes from spring. Fertilizer-N decreased C:N ratio at the spring sampling but not at the summer or fall timings. First-order decay constants ranged from 0.00075 to 0.00300 day⁻¹ for surface HRW and incorporated corn, respectively. This equates to a timeframe of 231–929 days for 50% of residue to decompose. Additions of fertilizer-N to increase residue decomposition were not supported by the data but incorporation of residue by tillage and lower C:N crop types did result in more rapid decomposition. Relatively slow rates of decomposition occurred, particularly when surface applied, and these estimates can be used to improve residue management in semi-arid regions.

Organic amendments enhance soil quality in agroecosystems, although they may modify the dynamics of greenhouse gas (GHG) emissions, highlighting complex interactions between soil management and environmental sustainability. A field experiment was conducted in the semiarid region of Iran to evaluate the effects of barley residues (BR), sheep manure (SM), and their combination (BR+SM) on soil carbon dioxide (CO₂) and nitrous oxide (N₂O) emissions under maize and mungbean. In mungbean, both SM and BR+SM resulted in higher CO₂ fluxes than BR. Conversely, in maize, cumulative CO₂ emissions were similar among treatments. Under mungbean, BR+SM exhibited higher soil N₂O values than SM and BR. The lowest cumulative CO₂ (4.77 ± 0.24 and 5.29 ± 0.37 Mg ha⁻¹ year⁻¹ for maize and mungbean, respectively) and N₂O (4.73 and 3.00 kg ha⁻¹ year⁻¹ for maize and mungbean, respectively) values were measured in the BR, whereas the BR+SM resulted in significantly high cumulative CO₂ and N₂O under both crops. Cumulative CO₂ fluxes were 21.5% and 53.5% lower in the BR than BR+SM under maize and mungbean, respectively. Similarly cumulative N₂O was 48% lower in the BR than in the BR+SM treatment under the mungbean cropping system. Application of BR can be considered as an effective alternative management strategy in terms of lowering GHG emissions under maize and mungbean. By exploring the impact of organic input management on soil carbon and nitrogen dynamics in semiarid cropping systems, our study provides key insights for enhancing agricultural sustainability, while reducing GHG emissions.

Hydrologic modeling studies within the United States frequently utilize the USDA-Natural Resources Conservation Service State Soil Geographic (STATSGO, 1:250,000 resolution) or Soil Survey Geographic (SSURGO, 1:24,000 resolution) database to characterize soil properties. The finer resolution of SSURGO enables more precise spatial modeling that is beneficial in locating hydrologically vulnerable regions. However, the coarser-resolution STATSGO results in quicker simulation runtimes, which can be computationally necessary in larger watersheds and for multi-decadal estimation periods. Extending runtime by several minutes for a single simulation translates into multiple days during calibration and optimization modeling, for which hundreds to thousands of runs may be needed. We developed a method to aggregate SSURGO using soil taxonomy while maintaining distinctions critical to hydrologic processes. We automated this process in R for the Soil and Water Assessment Tool (SWAT; https://www.climatehubs.usda.gov/hubs/international/tools/soil-and-water-assessment-tool) soil input data. Our method identifies hydrologically sensitive SSURGO map units, aggregates them up to the taxonomic subgroup level, and then creates the SWAT-required inputs from the subgroup characteristics. Soil horizons are then standardized by depth-weighting the SSURGO horizons. The taxonomic SWAT model ran twice as fast as the SSURGO model, predicted similar nutrient and sediment losses, and matched SSURGO identification of hydrologically vulnerable areas. The STATSGO model ran most quickly but also held the most water in the soil profile, likely due to much larger map units (309 ha each vs. 26 ha for SSURGO and 52 ha for taxonomic). Conversion of SSURGO into a taxonomy-based input layer supports more exploratory research by reducing processing time while maintaining similar precision levels.

This case study seeks to assess the long-term impact of manure usage on soil health and water under on-farm conditions. Explicitly, we concurrently monitored nutrient concentrations in shallow groundwater (nitrogen and phosphorus) and related in-field soil health indicators (permanganate oxidizable carbon, mineralizable C, and autoclaved citrate extractable-protein) on two fields located in northcentral Ohio with a historic legacy of annual cropping with and without manure utilization. Results indicated the usage of manure as a main source of nutrient can lead to lower nutrient concentrations for nitrogen in local shallow groundwater but showed virtually no direct influence on measurable soil health. These initial on-farm condition results are encouraging from the water quality perspective as they suggest that management alternatives such as wider utilization of manure associated with reintegration of crops and livestock could help reduce environmental impacts.

Degraded cool-season grass pastures pose a major challenge for sustainable forage production in the southeastern United States. Orchardgrass (OG; Dactylis glomerata L.), a widely used forage species, often exhibits poor persistence under suboptimal management and environmental stress, requiring restoration. Strategies that minimize soil disturbance while improving productivity and soil quality are needed to support long-term pasture sustainability. This study evaluated six low-disturbance strategies to restore OG pastures while preserving soil quality: (1) control (C-OG), (2) synthetic N fertilization (OG+N; 67 kg N ha⁻¹), (3) fall-seeded alfalfa (Medicago sativa L.) (FA), (4) spring-seeded alfalfa (SA), (5) FA combined with crabgrass (Digitaria sanguinalis L.; CG) (FA+CG), and (6) SA+CG. Treatments were applied from 2021 to 2022 in Spring Hill, TN, and evaluated for forage mass (FM), root biomass, and soil carbon (C) and nitrogen (N) concentrations. The OG-N treatment produced the greatest FM (2390 kg DM ha⁻¹, where DM is dry matter), while C-OG yielded the least (1927 kg DM ha⁻¹). Alfalfa and alfalfa+CG treatments produced intermediate yields, averaging 2159 kg DM ha⁻¹, and did not differ among them. Root biomass declined over time across all treatments but was unaffected by restoration strategy. Soil C and N concentrations remained stable throughout the 2-year period. These findings indicate that both N fertilization and legume-grass mixtures can enhance productivity without soil disturbance or nutrient loss. Integrating alfalfa and CG into existing OG pastures offers a sustainable restoration approach that supports forage production while maintaining soil health.

Gap-filling is used to mitigate yield losses in different legumes. There is scanty information on this mechanism of yield compensation in the cowpea [Vigna unguiculata (L.) Walp]. This study investigated responses of yield and yield components to plant density in some accessions of cowpea at Minjibir and Shika locations. The randomized complete block design, in a split-plot arrangement in three replicates, was used. The main plots consisted of four plant densities, while the sub-plots consisted of six cowpea accessions. Results showed that plant density and environment affected yield and yield components. Total grain yield increased as plant density increased at both locations and was highest in the accession DANILA (1793.3 kg ha⁻¹) at 99,999 plant ha⁻¹ and lowest in the accession IT98K-205-8 (1100 kg ha⁻¹) at 33,333 plants ha⁻¹. Pod yield was positively correlated with total grain yield at Minjibir (0.267*) and Shika (0.917**) and when data were combined (0.990**). Shelling percentage was negatively correlated with total grain yield when data were combined (−0.610**). Significant positive correlation between total grain yield and 100-seed weight as well as biological yield was observed at Shika. Harvest index was positively correlated with total grain yield (0.407**) at Minjibir. The study concludes that erect accessions (IT93K-452-1 and IT98K-205-8) and semi-erect accessions (IT99K-573-1-1 and IT08K-150-27) could be adopted for cultivation at 133,333 plants ha⁻¹, while prostrate accessions (IT89KD-288 and DANILA) could be cultivated at 99,999 plants ha⁻¹ at Minjibir. The accessions IT93K-452-1, IT98K-205-8, IT99K-573-1-1, and IT08K-150-27 could be cultivated at Shika, irrespective of plant density.