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

Authors: ZHANG, JIUQUAN - Chinese Academy Of Agricultural Sciences; VARCO, JAC - Mississippi State University; Adeli, Ardeshir

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2016
Publication Date: 9/7/2016
Publication URL: https://handle.nal.usda.gov/10113/63118
Citation: Zhang, J., Varco, J.J., Adeli, A. 2016. Short-term and seasonal soil nitrogen dynamics and recovery by bermudagrass irrigated with 15N labeled swine lagoon effluent. Plant and Soil. 1-15.

Interpretive Summary: A better understanding of short-term crop utilization and recovery of manure derived nitrogen (N) is necessary to minimize N losses and improve implementation of nutrient management practices. Modern confined animal feeding operations in the southeastern United States with respect to swine flush manure into anaerobic lagoons to facilitate decomposition. The resulting effluent N is approximately 84% ammonium (NH4+-N) with the balance as organic-N, (14 %) and < 2% nitrate (NO3—N). Effluent is utilized by irrigating forages with spray-type equipment to reduce lagoon volume and the likelihood of discharges and to derive irrigation and nutrient input benefits. Although N dynamics and loss of NH3 from chemical fertilizer application is well documented, reports on N fate and dynamics following swine lagoon effluent application are limited. The fate of N in effluent is of particular interest due to its impact on the environment and importance for crop growth. However, systematic studies to accurately determine the fate of effluent N, particularly NH3 losses through volatilization under various environmental conditions are limited. Therefore, the objective of this study was to determine the short-term dynamics of bermudagrass and soil N recovery from applied anaerobic swine lagoon effluent labeled with an enrichment of 15N as influenced by irrigation timing within a growing season.

Technical Abstract: The experiment was conducted at a commercial swine operation located in Lowndes County, Mississippi in an acid Vaiden silty clay (very fine, montmorillonitic, thermic Vertic Hapludalf) used in this study is representative of the Alabama and Mississippi Blackland Prairie major land resource area. A split-plot design with irrigation events (June, July, and September) as main plots (main treatments) and six sampling times (0, 1, 2, 3, 7, 14 days following irrigation events) as subplots; therefore, the main treatments have 3 levels and the sub treatments have 6 levels, making 18 subplots for each replicate. A randomized block design was used for main plots, while a completely randomized design was used for subplots. Four replicates were used in this study. Anaerobic swine lagoon effluent was labeled with enriched (15NH4)2SO4 and applied to the soil. Microplots having a dimesntion of 1- x 1-m were established for each irrigation event (main plots) and soil samples and bermudagrass was harvested on day 0, 1, 2, 3, 7, and 14 (subplots) following irrigation. Application in July when bermudagrass growth was most active resulted in effluent 15N plant recoveries of 59%. Crop recovery for June and September irrigation events was 33%. A majority of nitrification of effluent NH4+-N occurred within 24 h to 48 h following application. Volatile losses of NH3 were apparent within 24 h prior to significant nitrification and uptake, while denitrification loss was likely the result high soil moisture content once NO3- began to accumulate. Estimated total volatile N losses were 44.8, 4.9, and 29.8% of the irrigation events in June, July, and September, respectively. In conclusion, 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.