Swine Lagoon Effluent Applied to ‘Coastal’ Bermudagrass: I. Forage Yield, Quality, and Element Removal
1985
Burns, J. C. | Westerman, P. W. | King, L. D. | Cummings, G. A. | Overcash, M. R. | Goode, L.
Swine (Sus scrofa domesticus) production in confinement requires economical and environmentally safe waste management systems. Anaerobic lagoons require periodic removal of effluent for land application to avoid lagoon overflow in humid regions. The objective of this experiment was to determine the utilization potential and the environmental effects of applying swine lagoon effluent to ‘Coastal’ bermudagrass [Cynodon dactylon (L.) Pers.]. Effluent loading rates to apply approximately 335, 670, and 1340 kg of N ha⁻¹ yr⁻¹ were evaluated. The experiment was a randomized complete block with three replications and was conducted for 6 yr on a loamy, siliceous, thermic Arenic Paleudult (two replications) or a fine-loamy, siliceous thermic Typic Paleudult (one replication). The highest application rate resulted in additions of N, P, and K at about 4, 10, and 8 times, respectively, the normally recommended fertilizer applications for high yields of bermudagrass hay. Effluent loading rates altered dry matter yields with the high and medium rates being similar (15 800 and 14 200 kg ha⁻¹) but greater than the low rate (10 800 kg ha⁻¹). Severe winters injured stands most on the medium and high loading rates and were associated with soil characteristics. Concentrations of P, K, Ca, Mg, Mn, and Zn were increased in forage by increased effluent loading rates, while Cl⁻, Cu, Fe, and Na varied. Effluent loading rates significantly increased in vitro dry matter disappearance 3 of the 6 yr and N concentrations all years, especially from the low to medium loading rates (quadratic effect). High applications of effluent greatly increased the concentration of nitrates in the forage to levels that approached, but did not exceed, concentrations unsafe for ruminants. The medium and high rates resulted in large additions of elements not recovered in the forage and could have environmental implications as to effects on the soil, groundwater, and surface runoff.
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