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Cropping systems in semiarid regions have frequently relied on continuous tillage and irrigation, but declining groundwater resources have prompted a greater focus on conservation practices to improve soil health and water storage. We compared soil health responses from cotton production systems in semiarid, coarse-textured soils with different crop management strategies under high or low irrigation levels. Management systems included continuous cotton with conventional tillage (CCCT) compared to no-till cotton with a rye cover crop (NTCR) and no-till cotton with a wheat-fallow rotation (NTCW), including high or low irrigation zones within each system. Samples were collected annually from two bulk soil depths (0–10 cm and 10–20 cm) and root-associated soils 7 years after systems were established and continued for 2 years. We found that cropping system, but not irrigation level, altered soil microbial communities and other soil health indicators. Despite variation between study years and sampling zones, the conservation systems had greater soil microbial community size via ester-linked fatty acid methyl ester (EL-FAME or FAME) analysis, extracellular enzyme activities, and soil organic matter than the CCCT system. The NTCW system also had greater arbuscular mycorrhizal fungi FAME abundance. Our study suggests that no-till and conservation strategies such as cover cropping and rotation can improve biological soil health indicators in these sandy semiarid soils even with limited irrigation. [ABSTRACT FROM AUTHOR]

A 30-d experiment was conducted to evaluate daily and cumulative gas fluxes of N2O, CH4, and CO2 produced by manure from Angus-crossbred steers grazing mature mixed-winter forage pastures [wheat, triticale, and rye (Triticum aestivum, Triticosecale rimpaui, and Secale cereal, respectively) and receiving N supplementation from two different sources. Steers received the following treatments: 1) mature mixed-winter pasture + ground corn (NCTRL), 2) NCTRL + 328 mg/kg of BW encapsulated calcium-ammonium nitrate (NIT) and 3) NCTRL + 124 mg/kg of BW urea (CTRL). All ground corn was supplemented at 0.3% BW. Treatments NIT and CTRL were isonitrogenous. Feces were collected and composited (1 kg as-is) within treatment, within block (3 blocks; 4 steers/treatment/block; 3 fecal composites/treatment). Gas samples were collected from static chambers previously installed in an area excluded from grazing. After 3 d, composites were deposited on the soil surface inside the chamber. Four subsamples were taken per deployment time per chamber, separated by 10-min intervals (t0, t10, t20 and t30) and injected into an evacuated 125-mL serum vial. Gas samples were collected every other day between 0900 and 1100 h and analyzed using a gas chromatograph. Data were analyzed as a randomized complete block design, with chamber as the experimental unit, using the MIXED procedure of SAS. No treatment × day interaction (P ≥ 0.145), nor treatment (P ≥ 0.622) effect were observed on daily-flux data for N2O, CH4, and CO2; however, a day effect was observed (P ≤ 0.001) where all gases peaked on d 2 post-manure application on the soil. Cumulative emissions were not different among treatments for N2O, CH4, and CO2 (P ≥ 0.663). Although it was expected for encapsulated calciumammonium nitrate to increase N2O emissions, such effect was not observed. Therefore, it appears that encapsulated calcium-ammonium nitrate does not affect manure greenhouse gas emissions. [ABSTRACT FROM AUTHOR]