EFFECTS OF SWINE LAGOON EFFLUENT APPLICATION ON CHEMICAL-PROPERTIES OF A LOAMY SAND

In order to determine the effects of lagoon effluent application on so il chemical properties, swine lagoon effluent was applied to land with a 10% slope by an overland flow irrigation system on hybrid bermudagr ass (Cynodon dactylon L. Pers.) and annual ryegrass (Lolium multiform Lan). Treatments included a control with no nutrient additions, ammoni um 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 Ma rvyn loamy sand (fine-loamy, siliceous, thermic, Typic Kanphapludults) . At the termination of the experiment, soil core samples were taken t o 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 an d ammonium nitrate applications supplying the N loading resulted in a buildup of NO3-N, especially for the high N loading rate. Soil NO3-N i n the lower depths throughout soil profiles reached approximately 30 m g kg(-1). Application of lagoon effluent resulted in significant P bui ldup to a depth of 40 cm. Mehlich-I extractable P accumulated to as hi gh 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. Extrac table soil K concentration increased with increasing rates of lagoon e ffluent application. The application of swine lagoon effluent resulted in a decrease in soil pH and an increase in soluble salt accumulation . (C) 1998 Published by Elsevier Science Ltd.