Abstract
Fertilizer recommendations for intensive grazed swards for dairy cows were suggested by estimating decreases in available nutrients throughout the grazing period in 48 paddocks in the eastern, central and northern parts of Hokkaido. Decreases in available nutrients in pastures throughout the grazing period were determined by deducting available nutrients in excretions from nutrition intakes. Available nutrients in excretions were estimated by multiplying the amounts of nutrients in excretions based on the results of previous studies by conversion factors recommended for manure application in Hokkaido. Fertilizer application rates, decreases of available nutrients in pastures and removal of nutrients by trimming were able to explain the differences in available nutrients in soil of 0-5cm in depth before and after the grazing period. Decreases of available nutrients in pastures depended on herbage intake but not on the region or grass species. Averages values of decreases in available nutrients in pastures were nearly the same as fertilizer recommendations for pastures for dairy cows in a previous report. Based on the average decreases in available nutrients in the 48 paddocks, 4±2gN/m2 for grass/clover pasture, 8±2gN/m2 for grass pasture, and 3±1gP2O5/m2, 5±1gK2O/m2 for all pastures were recommended as amounts of fertilizer to be applied to pastures for dairy cows.
