Rates of soil chemical changes with eleven annual applications of cattle feedlot manure

Abstract

Manure was applied at various rates to nonirrigated and irrigated Dark Brown Chernozemic soils, respectively, using three tillage methods of incorporation. Soil acidity (pH), estimate of soluble salts (EC), sodium adsorption ratio (SAR), and accumulation of Na, Ca + Mg, SO4 and Cl in the soil were determined annually from 1974 to 1984. The rates of change with time were mostly linear and varied with the level of manure applied and irrigation regime. The soil became more acidic with time; soluble Na and Cl increased at rates similar to or less than those applied; souble Ca + Mg increased at rates greater than those applied; and changes in the soluble SO4 were poorly correlated with time. Regression analyses from 1974 to 1977 and 1978 to 1984, under irrigated conditions, indicated that the rates of change were generally less in the latter period. Thus, the losses of applied constituents were higher between 1974 and 1977 than between 1978 and 1984. However, various soluble constiuents from the annually applied manure accumulated in the soil even at the recommended rate, and the potential for leaching of various soluble salts and nutrients to groundwater is increased. -from Authors