Double-Cropped Soybean and Wheat with Subsurface Drip Irrigation Supplemented by Treated Swine Wastewater

Abstract

The wastewater from swine production facilities has been typically managed by treatment in anaerobic lagoons followed by land application. However, there have been considerable advances in superior treatment technologies. Wastewater from one of these technologies was effective for subsurface drip irrigation of bermudagrass. The objectives of this experiment were to assess accumulation of soil nitrogen and carbon along with grain yield, dry-matter accumulation, and plant nitrogen accumulation of soybean [Glycine max (L) Merr., cv.] and wheat [Triticum aestivum (L), cv.] when supplementally irrigated with treated swine effluent via subsurface drip irrigation (SDI). The soil series was Autryville loamy sand (loamy, siliceous, subactive, thermic Arenic Paleudults). Its low unsaturated hydraulic conductivity of 0.0017 ± 0.0023 mm h−1 caused problems with water movement to either the soil surface or laterally to adjoining soybean and wheat roots. This condition contributed to complete crop failure in soybean in 2 years and generally poor yields of wheat. In a good rainfall year, the soybean yield was somewhat satisfactory and benefited from the supplemental irrigation. In that year, nonirrigated and irrigated soybean mean yields were 1.55 versus 1.98 Mg ha−1, respectively. The mean yield of wheat was only 1.06 Mg ha−1, and it was not affected by irrigation. The means for soil nitrogen and carbon in the 0- to 15-cm depth were 414 and 5,679 mg kg−1, respectively, and they were not affected by the water treatments. Thus, neither soil conditions nor soybean/wheat production were greatly enhanced by the SDI system.