Effects of swine lagoon effluent application on chemical properties of a loamy sand

In order to determine the effects of lagoon effluent application on soil chemical properties, swine lagoon effluent was applied to land with a 10% slope by an overland flow irrigation system on hybrid bermudagrass (Cynodon dactylon L. Pers.) and annual ryegrass (Lolium multiform Lan). Treatments included a control with no nutrient additions, ammonium nitrate at 560 kg N ha−1 yr−1, and swine lagoon effluent at 560, 1120, and 2240 kg N ha−1 yr−1. Soil on the research site is a Marvyn loamy sand (fine-loamy, siliceous, thermic, Typic Kanphapludults). At the termination of the experiment, soil core samples were taken to 120 cm, and depth-incremental samples were analyzed for total C, NH4-N, NO3-N, Mehlich-I extractable P, K, Ca, Mg, Cu, Zn, and Mn, soil pH and electrical conductivity. Treatment had no significant effects on soil NH4-N and extractable soil Cu, Zn, and Mn concentrations. Lagoon effluent application did not increase soil total C. Lagoon effluent and ammonium nitrate applications supplying the N loading resulted in a buildup of NO3-N, especially for the high N loading rate. Soil NO3-N in the lower depths throughout soil profiles reached approximately 30 mg kg−1. Application of lagoon effluent resulted in significant P buildup to a depth of 40 cm. Mehlich-I extractable P accumulated to as high as 115 mg kg−1 on the upper portion and 40 mg kg−1 on the lower portion of the sloping land in the surface 0–20 cm soil layer. Extractable soil K concentration increased with increasing rates of lagoon effluent application. The application of swine lagoon effluent resulted in a decrease in soil pH and an increase in soluble salt accumulation.