Agricultural & Environmental Letters最新文献

Soil health can differ across cropping systems because of variation in edaphic and management factors. We evaluated how biological indicators of soil health (soil organic matter [SOM], permanganate oxidizable carbon [POXC], mineralizable carbon [MinC], autoclaved-citrate-extractable [ACE] protein, and potentially mineralizable nitrogen [PMN]) compared across four common Wisconsin cropping systems: grazed cool-season pastures, forage-based rotations that included perennial legumes or grasses, annual rotations receiving manure, and annual rotations receiving synthetic fertilizers. Biological indicators of soil health were up to 195% greater in pastures than other cropping systems. MinC, POXC and PMN were 10%–90% greater in forage-based rotations than annual cropping systems, but only MinC and POXC were greater in annual systems with manure compared to those without manure by 35% and 7%, respectively. Perennial vegetation and livestock integration offer the greatest potential to increase biological indicators of soil health in agricultural lands.

To better understand cover crop benefits and receive nitrogen scavenging credits for cover cropping, farmers need simple and robust methods of predicting cover crop biomass production. A new regulation focused on improving nitrogen management on over 200,000 ha of irrigated land in the central coast of California motivated us to evaluate if the shoot length of rye (Secale cereale L., ‘Merced’) and triticale (× Triticosecale Wittmack, ‘Pacheco’) could predict shoot biomass. Field samples for rye (n = 162) and triticale (n = 126) were collected at various developmental growth stages from organic and conventional vegetable farms and planting date trials, across multiple soil types, planting times, row spacings, and plant densities. Main shoot length was well-correlated with oven-dry shoot biomass for rye (r² = 0.87) and triticale (r² = 0.88). This provides farms in California and beyond with a simple, robust method to estimate cover crop shoot biomass.

Biochar is used as a soil amendment for improving soil health. Biochar is known to possess high adsorption capacity for nutrient ions, especially toward NH₄⁺. However, there is limited information regarding the direct binding mechanisms of NH₄⁺ on biochar. Although few infrared spectroscopic studies were conducted by characterizing the biochar solid phase, no research was reported, in which the adsorption mechanism was deciphered in the presence of water. Here we report NH₄⁺ adsorption mechanism on pinewood biochar using in situ attenuated total reflectance Fourier transform infrared spectroscopy. The results indicated that NH₄⁺ adsorbed strongly on pinewood biochar at pH 8.5 and less at pH 5.5 as revealed by infrared band shifts and symmetry change. Macroscopic adsorption envelope corroborated the spectroscopic finding by resulting in higher adsorption capacity with increasing pH.

Infrastructure installation (e.g., pipelines) disturbs soils, often resulting in increased soil compaction (bulk density [Bd] and penetration resistance [PR]). The relationship of PR to Bd, gravimetric water content (Θg), and a suite of other properties were determined on seven topsoils to provide a model and database for reclamation specialists to use when assessing disturbed soils. Penetration resistance had a strong linear association with Bd, but higher Θg reduced the range of PR as Bd increased. Step-wise regression identified Bd, Θg, texture, clay speciation, and organic matter as significant factors to predict PR. The model predicts PR from <1 to 8 MPa and closely match measured values. Soil Bd and Θg contributed to 84% of the model's explained variation in predicting PR. This study provides a tool for reclamation specialists that aids in understanding the risks associated with disturbances and highlights the importance of keeping Θg low during installation of pipelines.

The first compilation of nutrient export coefficients for specific land uses in the United States was completed in 1980. Building off that effort, the “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database was developed in 2006 to summarize annual field-scale nitrogen (N) and phosphorus (P) runoff data from agricultural land uses. It also presents descriptive data such as land use, tillage, conservation practices, soil type, soil test P, slope, and fertilizer formulation, rate, and application method, along with runoff, precipitation, and soil erosion. Here, we update MANAGE to facilitate regional analyses, adding 27 studies and Level II ecoregion delineations for each of the 94 studies such that data are now available from 11 of the 50 North American Level II ecoregions, representing the major U.S. agricultural regions. This contemporary data repository is freely available from USDA Ag Data Commons to support scientific analyses, model evaluations, and management and policy decisions.

Rising concentration of surface O₃ threatens crop production and food security. To improve the evaluation and develop efficient adaptations, it is essential to study the effects of acute O₃ pollution. We adopted this study by open-top chamber (OTC) method and found that the fumigation of elevated O₃ (NF40) for short (tillering and jointing, heading and ripening) and long periods during rice growth reduced the grain yield by 17, 19 and 25%, respectively, showing that both of the acute and chronic O₃ pollution reduce rice production. Moreover, in comparison with the plants under chronic O₃ pollution, grain yield was increased when O₃ was removed at different stages: 32% increment at tillering and jointing and 34% increment at heading and ripening. These results suggest a possibility to recover the yield loss in rice under O₃ pollution.

Soil aggregate stability is widely considered an indicator of soil health. However, there is a lack of test procedure standardization for this soil property. Presently, air-drying and manual grinding are commonly used in preparing samples for testing, which are time-consuming and labor intensive. This study evaluated oven-drying (65 °C) aggregates and processing by either disk or flail mechanical grinders as a way to improve efficiency of conducting aggregate stability analysis as compared with air drying and manual grinding. Surface soil samples were collected from forest, grassland, no-till, and cultivated areas across 22 fields in Oklahoma with textures ranging from sandy loam to clay loam. The stable fractions of oven-dried samples were highly correlated to the results of the analysis that used air-drying. The stable fractions of mechanically ground samples were also highly correlated with manually ground samples. Oven-drying in combination with either of the grinding methods is a suitable way of improving the efficiency of soil aggregate stability analysis.

Continuous corn (Zea mays L.) yield increases are required to promote economic development and support a larger population. Reducing the existing yield gaps is a potential strategy to accomplish this goal. The objective of this study was to evaluate yield trends, and gaps at different production levels in Mississippi using data from 2012 to 2021. Production levels considered were Mississippi yield contest (Yc), Mississippi State University hybrid testing trials under irrigation (Yp) and dryland (Yw), and actual yield (Ya) from USDA National Agricultural Statistics Service. Since 2012, Yc, Yp, and Ya are stagnant, and Yw has a nonsignificant positive trend. Averaged over 10 yr, a yield gap of 5.6 Mg ha⁻¹ between Yc and Ya, 4.1 Mg ha⁻¹ between Yp and Ya, and 2.0 Mg ha⁻¹ between Yw and Ya were noted at state level. Existing yield gap underlines current production limitations and necessitates adoption of improved agronomic practices.

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