Agronomy Journal最新文献

The application of composted sewage sludge (CSS) in crop production offers a sustainable solution for nutrient recycling and reducing reliance on mineral fertilizers. This study evaluated the residual effects of CSS on phosphorus (P) bioavailability and agronomic performance of maize and cover crops in P-fixing soils of the Brazilian Savannah (Cerrado). A field experiment was conducted over three cropping cycles (third, fourth, and fifth season), applying CSS at rates of 0, 5, 7.5, 10, and 12.5 Mg ha⁻¹ (wet basis) alongside conventional mineral fertilizer. The results showed that CSS significantly enhanced P uptake and maize (Zea mays L.) yield, with linear increases in plant height and grain yield (up to 28%) in the third season. Marandu grass (Urochloa brizantha (A. Rich.) T.Q. Nguyen cv. Marandu) growth responded positively to CSS, while a cover crop mix showed no response. Soil available P increased linearly with CSS rates, though climatic variability influenced outcomes. This work shows CSS demonstrates potential as a sustainable P source, but its efficacy depends on management practices and environmental conditions.

Tillage and cover cropping influence N, crop yield, quality, and soil properties in organic systems. This study evaluated four N application rates (0, 50, 100, and 150 kg ha⁻¹) in two industrial hemp (Cannabis sativa L.) types (grain and fiber) under conventional till (CT) and no-till (NT), with and without a legume cover crop (CC), in rotation with malt barley (Hordeum vulgare L.) from 2021 to 2024. Measurements included hemp biomass, grain and fiber yield, barley yield and grain quality, soil health indicators, and N use efficiency. Tillage was instrumental to hemp establishment, as NT with cover crop residue (NTCC) resulted in severe stand loss, preventing yield gains despite modest improvements in soil health indicators such as permanganate oxidizable carbon (POXC) and soil protein (typically 10–30 mg kg⁻¹). Because all CCs were established under full tillage, CC biomass could not be compared across tillage systems. Under CT, CCs enhanced hemp biomass and grain yield, and N fertilization up to 100 kg ha⁻¹ improved performance, whereas higher N provided no additional benefit. Barley crude protein and germination were unaffected by CC or N rate, although barley grain yield increased where hemp followed CC or higher N input, reflecting residual N rather than changes in soil C. No statistically significant differences in N use efficiency indices were detected among N rates. Soil health gains under NT did not translate into agronomic viability for hemp. Cover cropping and tillage should be integrated to optimize N use, productivity, and crop quality in organic hemp–barley systems.

Aquaponics is an alternative agricultural practice that combines aquaculture with hydroponics. It increases productivity while treating macronutrient loads on effluents. Yet, little information is available on productivity of commercial aquaponic models using saline waters, especially with biofloc technology (BFT) systems, which are characterized by high concentrations of total suspended solids and nitrate. This experiment evaluated the productivity and nutritional quality of the halophytes celery (Apium graveolens var. tall Utah) and sea asparagus (Salicornia neei), and the growth of a coastal fish, the Southern black drum (Pogonias courbina) in coupled aquaponic cultivation with clear water and BFT water. No previous report was found in the literature regarding celery cultivation coupled with saline BFT. The experiment was carried out for 18 weeks with a water salinity of 10 g L⁻¹. Floating rafts with halophytes (≈20 plants m⁻² per species) were placed inside tanks holding juvenile Southern black drums (21 ind m⁻³). Each water-treatment type was tested in three replicate tanks (15 m³). Both S. neei and A. graveolens produced more aboveground biomass in the BFT system than in clear-water tanks, with average shoot yields of 0.64 and 0.23 kg m⁻² 30 days⁻¹, respectively. The protein content of A. graveolens was significantly higher in BFT system, likely due to increased nitrogen availability. S. neei shoots showed highest P content in clear water, suggesting that the higher alkalinity and pH in the BFT system may have reduced P uptake. The growth of P. courbina fry did not differ significantly between treatments. Southern black drum, celery, and sea asparagus can be successfully cocultured in a biofloc-based aquaponic system.

Saline–alkaline soils pose significant challenges to agricultural productivity and crop growth. This study investigates the effects of chitooligosaccharide (COS) administration on the growth, ion homeostasis, and antioxidant defense systems of Brassica rapa in saline–alkaline field conditions over two consecutive growing seasons (2022–2023). The results showed that COS treatments significantly increased both shoot and root biomass, with the 0.3 g L⁻¹ dosage yielding the highest total weight based on statistical analysis (p < 0.05). COS also enhanced chlorophyll content, reduced Na⁺/K⁺ ratios, and stimulated antioxidant enzyme activities such as superoxide dismutase and catalase, while decreasing malondialdehyde accumulation. These findings suggest that COS enhances plant resilience to salt–alkaline stress by promoting biomass development, maintaining ionic balance, and strengthening oxidative defense mechanisms. This work demonstrates the potential application of COS as a sustainable biostimulant for agricultural practices in saline–alkaline environments.

Herbicide spray drift from roadside application sites poses risks of damaging nearby sensitive crops. The objective of this research was to investigate the impact of five herbicides (sulfometuron-methyl, indaziflam, triclopyr, triclopyr + clopyralid, and 2, 4-D + dichlorprop) commonly used to manage roadside vegetation at four application rates (0.01x. 0.05x, 0.1x, and 1x of the field rate) and six application timings (18, 12, and 6 weeks before planting, at planting, and 4 and 8 weeks after planting) on corn (Zea mays L.) and cotton (Gossypium hirsutum L.). Field studies were conducted at Upper Coastal Plain Research Station in Rocky Mount, NC, in 2022 and 2023. Although herbicide sensitivity varied by crop species, both species presented higher levels of injury and stunting for application conducted at planting and early post-planting, and at higher rates. In corn, sulfometuron-methyl caused the greatest damage. When applied at 4 weeks after planting, this herbicides caused injury of 100% and 48%, and height reduction of 66% and 16%, at 0.1x and 0.01x rates, respectively. In cotton, synthetic auxin herbicides, particularly 2, 4-D + dichlorprop and triclopyr, were the most damaging post-emergence. For instance, 2, 4-D + dichlorprop applied 4 weeks after planting at the 0.01× rate caused 78% injury and 25% height reduction. This study highlights the importance of herbicide selection and application timing when spraying along roadsides to minimize the risk of spray drift damaging nearby corn and cotton fields.

Alfalfa (Medicago sativa L.) is an important forage crop in US agriculture, especially for dairy and livestock, due to its high nutritional value and environmental benefits. However, frequent machinery traffic during harvests can lead to soil compaction and damage to regrowing plants, adversely affecting yield, forage quality, and soil health. Our study evaluated the effects of controlled traffic farming (CTF), varying tire inflation pressures, and different forage harvest methods (silage vs. hay) on alfalfa yield and quality, and soil compaction. Field and plot experiments were conducted at two Wisconsin sites. Our results indicated a negative correlation between alfalfa yield and machinery traffic intensity. Tire inflation pressure effects on yield were variable: low and medium pressures tended to reduce yield compared to no-traffic controls, while high pressure showed no yield effect. Soil compaction was notably higher in areas with direct traffic, particularly at 0- to 10-cm and 10- to 20-cm depths, and silage harvest management generally resulted in greater soil compaction than hay management. These findings highlight the complex interactions between machinery traffic, alfalfa yield and quality, and soil structure. While CTF and tire pressure adjustments did not produce immediate improvements in all areas, their potential to reduce long-term compaction is important for sustainable alfalfa management. This underscores the need to balance short-term productivity with soil conservation practices, especially in dairy systems where high-quality forage and soil health are essential for long-term productivity.

The objective in this study was to identify yield gaps and management factors that limit the yield of cassava (Manihot esculenta Crantz) in tropical and subtropical regions of Brazil. A total of 303 cassava fields were analyzed, and the yield potential was estimated using the Food and Agriculture Organization of the United Nations (FAO) model for agroecological zones for tropical regions and the Simanihot model for subtropical regions. Yield-limiting management factors were identified using regression tree analysis, and the optimal values of the key variables were determined using threshold functions (boundary). The estimated yield gap was 34.2 Mg ha⁻¹ in tropical regions and 27.7 Mg ha⁻¹ in subtropical regions. In the tropical regions, the most limiting factors were planting density, planting date, land tenure, and irrigation. In the subtropical regions, planting density, planting date, row spacing, and desiccation were the most important constraints. Optimal values for planting density were 13,000 plants ha⁻¹ for tropical and 11,000 plants ha⁻¹ for subtropical regions. The recommended planting dates to achieve maximum yields were by November 15 in tropical areas and by September 27 in subtropical areas. These results show the importance of adapting cultivation practices to regional conditions in order to close yield gaps and improve cassava yields in Brazil.

This study quantifies the effect of breeding and water supply on maize (Zea mays L.) yields, yield components, grain quality, and water use efficiency in Bayer legacy maize hybrids. Thirty-eight hybrids released from 1980 to 2020 were grown under three irrigation levels (non-irrigated, partially, and fully irrigated) in a 3-year experiment in Nebraska. Results indicate a significant grain yield increase across all irrigation treatments, with an average genetic gain of 111 kg/ha/year. New hybrids without irrigation produced as much yield as old hybrids with irrigation. Kernel number and weight increased with the year of hybrid release, with the kernel number being the primary driver of yield increase. This coincided with a reduced anthesis-silking interval (delta of 3 days between old and new hybrids). Grain protein concentration decreased by 1% from 1980 to 2020 following a dilution curve. Starch concentration increased by the same amount (∼1%), while oil concentration remained unchanged. Water use efficiency, defined as grain yield per water supply unit (growing season rain and irrigation), increased by 28% in the 40-year period. We concluded that maize breeding for high yields has indirectly affected several plant traits, including water use efficiency improvement, which is very encouraging for the future of crop production in the face of increased weather variability and climate change. Furthermore, we concluded that yield increase is the result of increasing both yield potential and drought stress tolerance. Present results can assist decision-making regarding water management of modern hybrids and enhance our crop physiology knowledge.

Soybean [Glycine max (L.) Merr.] seeding rate is typically set uniformly across entire fields, overlooking within-field variability. On-farm experimentation (OFE), combined with precision agriculture (PA) tools, can help determine optimal seeding rates across different areas of a field, generating data that support variable seeding rate decisions. Soil characteristics are factors that can help understand spatial variability in soybean yield and profit, assisting in identifying fields where variable rate seeding is suitable. This study aimed to (i) determine the economically optimal seeding rates per field and per soil type using OFE and (ii) benchmark current farmer seeding rates against the economically optimal seeding rates per field and across soil types. Eleven on-farm soybean seeding rate trials were conducted in Nebraska, using variable-rate prescriptions and randomized block designs. Yield data were cleaned and analyzed using mixed models with lme4 package in R to determine the economically optimum seeding rate (EOSR) by field and soil type level and to evaluate seeding rate effects on partial profit. The EOSRs across fields varied from 175,000 to 350,000 ha⁻¹ and could be reduced in nine out of 11 fields without impacting yield and partial profit. Similarly, EOSRs for soil types ranged from 175,000 to 351,000 seeds ha⁻¹, with significant variation among soil types. This study expands the understanding of within-field variability in soybean seeding rates based on soil characteristics and highlights the opportunity to reduce seeding costs to optimize partial profit in farmers’ fields.

While cover crop adoption in the United States has increased, limited research exists on the impact of cover crop mixtures on soybean (Glycine max (L.) Merr.) production. This study evaluated the effects of cereal rye (Secale cereale L.), cereal rye + hairy vetch (Vicia villosa) mixture (rye + vetch), and cereal rye + crimson clover (Trifolium incarnatum) mixture (rye + clover), along with pre-plant and at planting termination timings, on total aboveground biomass, nitrogen (N) accumulation, C:N ratio, soil inorganic N, and soybean yield. A 3-year study at two Delaware locations revealed that at planting terminated rye + clover produced the highest biomass, reaching 17.56 Mg ha⁻¹ in 2020, exceeding regional averages. Grass + legume mixtures generally outperformed monoculture rye in biomass and N content, except in 1 year at Middletown. The C:N ratio of mixtures (9:1–43:1) was consistently lower than monoculture rye (17:1–68:1). Soybean yield was influenced by cover crops only in 2018 with rye + vetch increasing yield by 0.45 Mg ha⁻¹ at Georgetown, but no differences were observed between rye + clover, rye, and control. The results suggest that rye + legume mixture (with low rye seed rate) can enhance biomass production, reduce C:N ratios, and potentially supply N through more rapid decomposition to high-yielding soybeans, particularly under irrigated conditions. This study highlights the benefits of grass + legume cover crop mixtures for improving biomass and N dynamics without compromising soybean yield.