Soil Nitrate Nitrogen Dynamics after Biosolids Application in a Tobosagrass Desert Grassland
- Pedro Jurado-Guerraa,
- David B. Wester *b and
- Ernest B. Fishb
- a Campo Experimental “La Campana”, Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias (INIFAP), Chihuahua, Chih., México 31100
b Department of Range, Wildlife, and Fisheries Management, College of Agricultural Sciences and Natural Resources, Texas Tech University, Lubbock, TX 79409
Dormant-season application of biosolids increases desert grass production more than growing season application in the first growing season after application. Differential patterns of NO3–N (plant available N) release following seasonal biosolids application may explain this response. Experiments were conducted to determine soil nitrate nitrogen dynamics following application of biosolids during two seasons in a tobosagrass [Hilaria mutica (Buckl.) Benth.] Chihuahuan Desert grassland. Biosolids were applied either in the dormant (early April) or growing (early July) season at 0, 18, or 34 dry Mg ha−1 A polyester–nylon mulch was also applied to serve as a control that approximated the same physical effects on the soil surface as the biosolids but without any chemical effects. Supplemental irrigation was applied to half of the plots. Soil NO3–N was measured at two depths (0–5 and 5–15 cm) underneath biosolids (or mulch) and in interspace positions relative to surface location of biosolids (or mulch). Dormant-season biosolids application significantly increased soil NO3–N during the first growing season, and also increased soil NO3–N throughout the first growing season compared to growing-season biosolids application in a year of higher-than-average spring precipitation. In a year of lower-than-average spring precipitation, season of application did not affect soil NO3–N. Soil NO3–N was higher at both biosolids rates for both seasons of application than in the control treatment. Biosolids increased soil NO3–N compared to the inert mulch. Irrigation did not significantly affect soil NO3–N. Soil NO3–N was not significantly different underneath biosolids and in interspace positions. Surface soil NO3–N was higher during the first year of biosolids application, and subsurface soil NO3–N increased during the second year. Results showed that biosolids rate and season of application affected soil NO3–N measured during the growing season. Under dry spring–normal summer precipitation conditions, season of application did not affect soil NO3–N; in contrast, dormant season application increased soil NO3–N more than growing season application under wet spring–dry summer conditions.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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