Agricultural & Environmental Letters最新文献

The Fertilizer Recommendation Support Tool (FRST) Project is a collaborative effort involving most land grant institutions, USDA branches, nonprofit organizations, and private industry. The FRST objectives are to develop a soil fertility community of practice, preserve soil test correlation and calibration data in a relational database, and develop a decision tool to provide consistent soil test interpretations. Released in April 2024, the interactive tool acts on an evolving database that contained 1455 P trials, 1316 K trials, and 143 S trials from 44 states and Puerto Rico by March 1, 2025. Decision tool outputs include an interactive county-level map of available data and an estimated critical soil test value. The FRST relational database is a repository for soil-test-based P, K, and S data to support data-driven management recommendations. Continued success of the FRST project and decision tool utility rely on collaboration and support from the soil-test-based nutrient management community.

Quizalofop-p-ethyl (QPE) can control glufosinate/glyphosate-resistant corn (Zea mays L.) volunteers in corn resistant to aryloxyphenoxypropionates (Enlist corn). Mixing QPE with broadleaf herbicides such as 2,4-D choline can be antagonistic. A new precision sprayer with a dual tank/boom system can apply two herbicides simultaneously through separate nozzles, potentially reducing chemical antagonism. The objective of this study was to evaluate the interaction of QPE + 2,4-D choline applied via single tank or dual tank/boom system for controlling glufosinate/glyphosate-resistant corn volunteers in Enlist corn. Bin-run glufosinate/glyphosate-resistant corn was planted at 54,000 seeds ha⁻¹ to mimic corn volunteers. At 14 days after application (DAA), the dual tank/boom application of QPE (39 g a.i. ha⁻¹) and 2,4-D choline (1064 g a.e. ha⁻¹) achieved 85% volunteer corn control, compared to 70% control with single tank mix. The single tank application of QPE + 2,4-D choline was 7%–26% antagonistic until 28 DAA. Conversely, dual tank application of QPE and 2,4-D choline was additive. Although dual tank application of QPE and 2,4-D choline did not have transient antagonism (14 DAA), it was otherwise eliminated by 28 DAA using the higher rate of QPE (77 g a.i. ha⁻¹) in the tank mix. By 28 DAA, volunteer corn control was ≥92% across all treatments, with similar corn yield and no crop injury. The results suggest that a dual tank/boom system provided better volunteer corn control at 14 DAA; however, control was similar when using a higher rate of QPE (77 g a.i. ha⁻¹) with 2,4-D choline in tank mix at 28 DAA.

Soil management assessment framework (SMAF) algorithms have not been validated for tropical soils, which can prevent proper SMAF-based soil health monitoring. This study tested SMAF's ability to detect soil health as affected by soil management practices in the Mid-South United States and Brazil for improving SMAF performance in tropical regions. Eleven SMAF studies published in Brazil (n = 166) and 56 from the Mid-South United States (n = 500) were compiled. Management groups were perennial (PER), no-till (NT), reduced tillage (RT), and conventional tillage (CT) systems. In the United States, SMAF soil quality index decreased as follows: PER ≥ RT ≥ NT = CT, while for Brazil, PER > NT = RT = CT. Macroaggregate and microbial biomass carbon scores under CT were overestimated, resulting in nonsignificant differences between conservation and conventional soil management. Revision of organic matter and textural parameters is needed to improve SMAF utilization in tropical agroecosystems.

Resin-extractable phosphate (PO₄-P) is a widespread sink-based measure of soil bioavailable phosphorus (P) used in biogeochemistry and soil fertility. However, acid elution of P may hydrolyze organic P and thus compromise measurement of PO₄-P. We evaluated sodium bicarbonate (NaHCO₃) as an alternative to sulfuric acid (H₂SO₄) for PO₄-P elution. We found 0.5 M NaHCO₃ achieved ≈100% PO₄-P recovery at higher initial PO₄-P concentrations (20 and 30 mg P/L), compared to 95%–98% with 0.25 M H₂SO₄. For 24 soil samples representing all 12 USDA soil orders, NaHCO₃ elution yielded 9.6% higher resin extractable PO₄-P than H₂SO₄. Additionally, the PO₄-P remaining in water extract after resin removal (H₂O_re-PO₄) was consistently quantifiable, and constituted up to 46% of total extractable PO₄-P. These results demonstrate (i) NaHCO₃ is a more effective eluent for resin extractable P than H₂SO₄, and (ii) H₂O_re-PO₄ should be quantified when measuring resin extractable P.

This study aimed to estimate mixed-species cover crop (CC) biomass and nutrient contents using remote sensing, as ground-based measurements are time-consuming and costly. Eleven CC treatments with varying grass-legume proportions (GLP) were sampled, and nutrient contents were determined along with multispectral imagery captured during the first and fourth weeks of March and the fourth week of April 2023. Biomass N (R² = 0.46–0.60) and K% (R² = 0.41—0.71) decreased with increasing GLP. The chlorophyll absorption ratio index and the normalized difference vegetation index closely followed the biomass nutrients N, P, and K combined yield (Bio_NPK) trend. Machine learning algorithms random forest (RF) and partial least square (PLS) regression were better for biomass (R² = 0.74 with RF) and N% (R² = 0.72 with PLS) prediction compared to the Bio_NPK prediction. These results are crucial for scientists to devise appropriate analysis approaches for estimating the benefits of mixed-species CC.

Soybean (Glycine max) is the most important protein crop being produced globally. Sulfur is essential for enhancing its nutritional quality, particularly by increasing S-containing amino acids. Gypsum, which provides calcium and sulfur, and cover crops, which improve soil health and indirectly affect nutrient dynamics, are promising management practices for enhancing soybean nutrient content. A 5-year study across three US. locations evaluated the effects of surface-applied gypsum and cover crops of cereal rye (Secale cereale) on continuous soybean production. The objective was to evaluate the soybean nutrient composition affected by these practices across various soil types and climatic conditions. Findings revealed consistent increases in soybean sulfur content with gypsum application, regardless of cover crop use. Responses of other elements were site-dependent. In the case of cover crops, significant changes in element composition were observed mainly at the Ohio site.