DISTRIBUTION OF NITROGEN FORMS IN SOIL RECEIVING CATTLE FEEDLOT WASTE

The paper reports on a study involving irrigated, continuous, grain sorghum plots on Pullman clay loam which received a total of 176 to 1,614 metric tons/ha of feedlot waste over an 8-year period. Differences in N forms and amounts observed among plots were confined mainly to the surface 30-cm soil layer. Increasing waste applications tended to increase the total N content, organic C content, nitrate content, N mineralization, and general biological activity of the respective plots. However, in most cases Duncan's multiple range test indicates the increases were satistically significant only at the higher rates. Chemical patterns of soil organic N forms and C/N ratios remained fairly constant, indicating the overall N distribution was being maintained.