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Short-term and seasonal soil nitrogen dynamics and recovery by bermudagrass irrigated with 15N labelled swine lagoon effluent

Zhang, Jiuquan, Varco, Jac J., Adeli, Ardeshir
Plant and soil 2016 v.410 no.1 pp. 437-451
Cynodon dactylon, Sus scrofa, acid soils, ammonia, ammonium nitrogen, ammonium sulfate, crops, denitrification, effluents, environmental factors, irrigation, leaching, nitrification, nitrogen, pig manure, probability, rain, silty clay soils, soil depth, soil sampling, soil water content, swine, volatilization, waste lagoons
Rapid and efficient utilization of swine (Sus scrofa domestucus) lagoon effluent nitrogen (N) by crops is necessary to minimize N losses and environmental pollution. The objective of this study was to determine the dynamics and fate of effluent N applied to bermudagrass (Cynodon dactylon (L.) pers.) using (15)N tracer technology as influenced by irrigation date. Methods Anaerobic swine lagoon effluent was labeled with enriched ((15)NH(4))(2)SO(4) and applied to an acid silty clay soil. Microplots (1 × 1 m) were established for each irrigation event (main plots) and soil was sampled and bermudagrass was harvested on day 0, 1, 2, 3, 7, and 14 (subplots) following irrigation. Soil sampling coincided with harvests to monitor effluent derived (15)N transformations. Application in July when bermudagrass growth was most active resulted in a plant (15)N recovery of 59 %. Crop recoveries for June and September irrigation events were equal at 33 %. Nitrification of effluent NH(4)(+)-N occurred rapidly within 24 h to 48 h following application. Rapid losses of effluent (15)N within 1 d suggest a high probability for NH(3) volatilization, while losses following rainfall and high soil moisture content in June infer denitrification was most active. Lack of (15)N detection in the 30 to 60 cm soil depth indicated a low probability of leaching losses, while unaccounted for (15)N was 45, 5, and 30 % for irrigation events in June, July, and September, respectively. Bermudagrass recovery, dynamics and fate of effluent N applied to an acid soil varied with environmental conditions affecting crop growth and N uptake and soil N transformations.