Search

Wheat (Triticum aestivum, L.) producers have the choice to retain or remove residue from the cropping system following grain harvest. In the U.S. Pacific Northwest and other regions, wheat residue is often sold to increase operational profitability, especially from higher-yielding systems. But there are several benefits to retaining residue, including recycling of mineral nutrients contained therein, though this is understudied. Therefore, the primary objectives of this research were to collect and analyze a large and diverse dataset on wheat residue nutrient uptake (N, P, K, Ca, Mg, S, Fe, Zn, Mn, Cu), develop tools to estimate nutrient amounts in residue, and make economic estimates of the fertilizer replacement value of those nutrients. This was accomplished by conducting replicated variety trials on five classes of wheat across many Pacific Northwest sites over two years, then collecting and analyzing data on wheat residue biomass, residue nutrient concentrations, and grain yield. The results showed that wheat residue contained a significant amount of nutrients, but was particularly concentrated in K. Production environment had the most substantial effect on residue mineral uptake amounts, due to site differences in yield and soil nutrient availability. To enable simple estimation of residue nutrient uptake across a broad range of wheat production levels, two estimation tools are presented herein. Economic analysis showed the substantial monetary value of residual nutrients. For example, in a high-yielding wheat crop (9 Mg ha−1), the average fertilizer replacement value of just residue N, P, K, and S was similar to the entire fertilizer budget to grow the crop (~$211 vs. $205 ha−1), not considering micronutrients in the residue or any nutrients removed through grain harvest. In making residue management decisions, wheat producers should consider the tradeoff between the immediate economic gains of residue sale and the multifaceted benefits of residue retention, including savings on future nutrient costs. [ABSTRACT FROM AUTHOR]

Approximately 37% of US milk production occurs in semiarid regions, providing an opportunity to recycle manure nutrients through a variety of cropping systems. Accurate prediction of nitrogen (N) mineralization is critical to determine manure application suitability in intensive irrigated agriculture as many crops in the region have quality parameters that are sensitive to N. Research was conducted in southcentral Idaho to evaluate N mineralization via a buried bag methodology to develop a predictive N‐mineralization model. The study was arranged in a randomized complete block design with manure application rates of 18, 36, and 52 Mg·ha−1 (dry weight basis) both annually and biennially with synthetic fertilizer and untreated check treatments. The crop rotation included small‐grain and broadleaf crops. In the final year of the study, preplant soil organic carbon, total nitrogen, and NO3–N concentrations were positively linearly correlated with manure application rate. Nearly five times as much N was mineralized annually in the 0‐ to 30‐cm depth as compared to the 30‐ to 60‐cm depth. Increased rates of N mineralization for each kilogram of added N occurred in years when residue from broadleaf crops (slope = 0.17) was applied as compared to years with manure only application (slope = 0.07). Stepwise modeling determined that the most predictive model for seasonal N mineralization (R2 = 0.79) included manure N, residue N, soil organic matter, and electrical conductivity. These results allow preplant N mineralization estimation and will prove critical for managing manure in semiarid regions for agronomic, economic, and environmentally sound crop production. Core Ideas: Tools are needed to estimate nitrogen (N) mineralization from applications of dairy manure in semiarid irrigated soils.N mineralization was affected by manure application rate, timing, and broadleaf residue N.Average manure N mineralization was 27% and 18% of N applied in the first and second years, respectively, following application.The incorporation of broadleaf residue with manure increased N mineralized to 41% of N applied.The best predictors of N mineralization were soil organic matter, soil electrical conductivity, manure N, and broadleaf N residue. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf (BYD) is one of the most common diseases of cereal crops, caused by the phloem‐limited, cereal aphid‐borne Barley yellow dwarf virus (BYDV) (Luteoviridae). Delayed planting and controlling aphid vector numbers with insecticides have been the primary approaches to manage BYD. There is limited research on nitrogen (N) application effects on plant growth, N status, and water use in the BYDV pathosystem in the absence of aphid control. Such information will be essential in developing a post‐infection management plan for BYDV‐infected cereals. Through a greenhouse study, we assessed whether manipulation of N supply to BYDV‐infected winter wheat, Triticum aestivum L. (Poaceae), in the presence or absence of the aphid vector Rhopalosiphum padi L. (Hemiptera: Aphididae), could improve N and/or water uptake, and subsequently promote plant growth. Similar responses of shoot biomass and of water and N use efficiencies to various N application rates were observed in both BYDV‐infected and non‐infected plants, suggesting that winter wheat plants with only BYDV infection may be capable of outgrowing infection by the virus. Plants, which simultaneously hosted aphids and BYDV, suffered more severe symptoms and possessed higher virus loads than those infected with BYDV only. Moreover, in plants hosting both BYDV and aphids, aphid pressure was positively associated with N concentration within plant tissue, suggesting that N application and N concentration within foliar tissue may alter BYDV replication indirectly through their influence on aphid reproduction. Even though shoot biomass, tissue N concentration, and water use efficiency increased in response to increased N application, decision‐making on N fertilization to plants hosting both BYDV and aphids should take into consideration the potential of aphid outbreak and/or the possibility of reduced plant resilience to environmental stresses due to decreased root growth. This work evaluates the effects of nitrogen supply on Barley yellow dwarf virus (BYDV) titer and disease progress in winter wheat. Nitrogen supply did not affect BYDV titer but could promote multiplication of the vector aphid Rhopalosiphum padi (Hemiptera: Aphididae). As nitrogen may also reduce early‐stage root development, it is suggested that ideally nitrogen application in high‐risk BYDV areas is conducted when aphids are absent, or following aphid control. However, this needs to be confirmed in field experiments. [ABSTRACT FROM AUTHOR]

Due to anaerobic conditions that develop in soils under flooded-rice (Oryza sativa L.) production, along with the global extent of rice production, it is estimated that rice cultivation is responsible for 11% of global anthropogenic methane (CH4) emissions. In order to adequately estimate CH4 emissions, it is important to include data representing the range of environmental, climatic, and cultural factors occurring in rice production, particularly from Arkansas, the leading rice-producing state in the US, and from clay soils. The objective of this study was to determine the effects of previous crop (i.e., rice or soybean (Glycine max L.)) and cultivar (i.e., Cheniere (pure-line, semidwarf), CLXL745 (hybrid), and Taggart (pure-line, standard-stature)) on CH4 fluxes and emissions from rice grown on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts) in eastern Arkansas. Rice following rice as a previous crop generally had greater (p<0.01) fluxes than rice following soybean, resulting in growing season emissions (p<0.01) of 19.6 and 7.0 kg CH4-C ha−1, respectively. The resulting emissions from CLXL745 (10.2 kg CH4-C ha−1) were less (p=0.03) than those from Cheniere or Taggart (15.5 and 14.2 kg CH4-C ha−1, resp.), which did not differ. Results of this study indicate that common Arkansas practices, such as growing rice in rotation with soybean and planting hybrid cultivars, may result in reduced CH4 emissions relative to continuous rice rotations and pure-line cultivars, respectively. [ABSTRACT FROM AUTHOR]

The buffering of phosphorus (P) in the landscape delays management outcomes for water quality. If stored in labile form (readily exchangeable and bioavailable), P may readily pollute waters. We studied labile P and its intensity for >600 soils and sediments across seven study locations in the United States. Stocks of labile P were large enough to sustain high P losses for decades, indicating the transport-limited regime typical of legacy P. Sediments were commonly more P-sorptive than nearby soils. Soils in the top 5 cm had 1.3-3.0 times more labile P than soils at 5-15 cm. Stratification in soil test P and total P was, however, less consistent. As P exchange via sorption processes follows the difference in intensities between soil/sediment surface and solution, we built a model for the equilibrium phosphate concentration at net zero sorption (EPC 0 ) as a function of labile P (quantity) and buffer capacity. Despite widely varying properties across sites, the model generalized well for all soils and sediments: EPC 0 increased sharply with more labile P and to greater degree when buffer capacity was low or sorption sites were likely more saturated. This quantity-intensity-capacity relationship is central to the P transport models we rely on today. Our data inform the improvement of such P models, which will be necessary to predict the impacts of legacy P. Further, this work reaffirms the position of labile P as a key focus for environmental P management-a view Dr. Sharpley developed in the 1980s with fewer data and resources., (© 2024 The Author(s). Journal of Environmental Quality published by Wiley Periodicals LLC on behalf of American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)