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Limited annual precipitation and increasing scarcity of irrigation water are forcing farmers in arid and semi‐arid regions to convert irrigated fields into dryland farming, yet their impacts on soil carbon (C) and nitrogen (N) fractions are not fully understood. This study evaluated changes in soil C and N fractions and forage production under four cropping systems after irrigation retirement in a semi‐arid condition. Treatments included an annual winter wheat forage (Triticum aestivum L.) (AWW), a perennial wheat (PW) forage (T. aestivum L. × Thinopyrum spp.) (PW), a mixture of native grasses (NG), and a pasture crop (PC = AWW and NG mixture). Evaluation of various soil C and N fractions, forage dry matter yield, and nutritive value parameters suggested that soil inorganic N and potentially mineralizable N (PMN) were 38%–45% and 36%–44% greater in autumn 2020 and 62%–68% and 46%–55% greater in spring 2021 under AWW and PW, respectively, than NG and PC. Soil potentially mineralizable carbon (PMC) was 58%–129% and 64%–138% greater under NG and PW than AWW and PC. The responses of other soil C and N fractions varied with soil sampling dates but not with crops or crop × sampling date interaction. Total forage dry matter yield was 4016, 7849, 12,517, and 13,869 kg ha−1 for AWW, PW, PC, and NG, respectively, and PW had the best forage nutritive value. These results suggest soil C and N mineralization could be enhanced by adopting perennial systems, including NG, PW, and PC, while PW maintains good‐quality forage production. Core Ideas: Information on crop productivity and soil health response to irrigation retirement in semi‐arid regions is lacking.The pasture crop and native grasses depleted soil's labile nitrogen reserve faster than annual or perennial wheat.Native grasses and pasture crops had the greatest forage yield, perennial wheat had the best forage nutritive value.Perennial wheat and grasses favored the accumulation of labile carbon (C), suggesting potential for long‐term C storage. [ABSTRACT FROM AUTHOR]

The Quick Wash (QW) treatment extracts phosphorus (P) from manure and municipal sludge (MS), producing an organic acidified by-product with adequate nitrogen (N):P ratio to meet crop N requirements. Yet, data on crop response to N using QW by-products are lacking. We evaluated the response of annual ryegrass (Lolium multiflorum Lam.) and potential N leaching in sandy soil to N applications using raw wastes, their corresponding QW by-products, and ammonium sulfate (AMS) fertilizer. Treatments included a control (no amendment added), raw and acid-washed chicken litter, dairy and swine manure, MS, and AMS at 100, 200, and 400 kg N ha−1. We found no significant differences in annual ryegrass yield and N uptake between the raw and acidified organic QW by-products. However, ryegrass produced 4–30% more biomass with AMS than organic amendments. The total residual soil inorganic N under AMS treatments ranged between 6.3 and 67.9 mg pot−1 and accounted for 5–17% of the total N applied, but it was <1% for all the organic amendments. We found no differences in soil N leaching between raw and acid-washed forms of each organic soil amendment. Our results indicated that acidified organic QW by-products can improve environmental quality by substantially reducing the amount of applied P with no penalties for crop yield losses compared to raw manure and MS. [ABSTRACT FROM AUTHOR]

Winter canola (Brassica napus L.) is an economically viable alternative crop for the semiarid southern Great Plains of the United States. Although land area under winter canola has increased in recent years, an independent guideline on fertility recommendation and their effects on crop growth and soil health is not available for the semiarid southern Great Plains region. This study aimed to evaluate winter canola growth, yield components, and nitrogen use efficiency (NUE) with different nitrogen application timings (NATs) in a semiarid irrigated condition. A 2-yr study was designed with two canola varieties (Riley and 46W94) and four NATs. Nitrogen treatments were F100 (100% of nitrogen applied in fall), S100 (100% of nitrogen applied in spring), FS50 (50% of nitrogen applied in fall and 50% in spring), and FSB25 (25% of nitrogen applied in fall, 25% in spring, and 25% before flowering). The winter dry matter accumulation was greater with the F100 N application, whereas the forage quality was better with the FS50 treatment. The highest seed yield of 2,539 kg ha-1 was from S100, which was not significantly different from FS50 and FSB25. The N use efficiency was the highest under FSB25, which uses 25% less N, followed by S100, FS50, and F100 treatments. The FS50 with 50% of N application in fall and 50% in spring was the most efficient N timing treatment when winter biomass accumulation, seed yield, and seed oil and protein contents were considered. [ABSTRACT FROM AUTHOR]

Cover crops can increase crop water productivity (CWP) and succeeding crop yield. However, cover crops adoption in the Southern High Plains of USA is slow due to limited water available for crop production. This study evaluated the effects of winter cover crops on soil water dynamics, corn silage yield and nutritive values, and corn silage CWP in a semi-arid irrigated condition. Three winter cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and control or no cover crop (NCC) were evaluated for soil water storage, cover crop biomass, corn silage yield, nutritive values, and crop evapotranspiration (ET), and the cover crop-corn silage system water productivity (SWP) under a no-till irrigated corn silage production system. All cover crop treatments reduced soil water storage before their termination in both years. However, water storage was higher for all cover crop treatments than for NCC during corn growth. Average CWP for corn was improved by 14–29% with cover crop mixtures over the NCC. Corn silage yield among cover crop treatments was 9–26% higher than NCC. Nutritive value components of cover crops such as non-fat carbohydrates, relative forage quality, and Ca and Mg were higher in the GBL and GL mixtures than the GB in one of the two years. This study demonstrated increased corn silage yield and water productivity with cover cropping. Cover crops mixtures with legumes could offer a high-quality alternative forage for crop-cattle integrated systems, including dairy producers in the Southern High Plains region. • Cover crop effects on soil water dynamics and water use was studied. • Soil water depleted during cover crop growth. • Cover crops improved corn yield by 9–26% and CWP for corn by 14–29%. • Cover crop mixtures with legumes produced a higher forage nutritive value. [ABSTRACT FROM AUTHOR]