Effect of 25 annual cattle manure applications on soluble and exchangeable cations in soil

Cattle manure contains a high level of soluble salts, and its application to agricultural land may alter soil properties and affect crop production. The purpose of this study, conducted in Fall 1998, was to evaluate the effect of 25 annual cattle manure applications on solution and exchangeable cations in surface soil (0 to 15 cm). Cattle manure was applied at rates of 0, 30, 60, and 90 Mg ha(-1) yr(-1) (wet weight) under nonirrigated conditions and at 0, 60, 120, and 180 Mg ha(-1) yr(-1) under irrigated conditions to a Dark Brown Chernozemic clay loam soil starting in Fan 1973. The composition and concentrations of solution cations were determined in Fall 1998 using the saturated paste extraction method, whereas the composition and concentrations of exchangeable cations were determined in Fall 1998 using the 0.1 M BaCl2 method. Although solution and exchangeable Na, K, and Mg increased significantly with the rate of manure application, Ca response varied. Cattle manure application also led to a higher sodium adsorption ratio and potassium adsorption ratio in soil solution and higher exchangeable sodium ratio and exchangeable potassium ratio on cation exchange sites under both nonirrigated and irrigated conditions. Greater leaching and crop removal may lessen the impact of manure application on soluble and exchangeable cations in an irrigated soil.