FORAGE GRASS RESPONSE TO HARVEST INTERVAL AND RECLAIMED WATER

Accumulation of dry matter and plant nutrients by perennial grass over the growing season is dependent upon harvest interval and availabilit y of water and applied nutrients. Mathematical models are frequently i ncorporated in the analysis, design, and operation of systems for land application of reclaimed water (municipal or agricultural). The objec tive of the present work was to measure response of warm-season Coasta l bermudagrass [Cynodon dactylon (L.)] to irrigation with reclaimed mu nicipal wastewater and to evaluate parameters for a simplified model. Grass was harvested at intervals of 2, 4, and 6 wk. Measurements inclu ded yields (dry matter and digestible organic matter) and plant nutrie nt uptake (N, P, and K). The probability model described time trends r ather well. The linear model parameter A showed linear dependence on h arvest interval Delta t over the range studied, in agreement with resu lts from the literature. Maximum values for a harvest interval of 6 wk were 16.5 Mg ha(-1) (dry matter), 8.0 Mg ha(-1) (digestible organic m atter), 350 kg N ha(-1) 57 kg P ha(-1), and 272 kg K ha(-1).