Yield and Quality Response of Subirrigated Meadow Vegetation to Nitrogen, Phosphorus and Sulfur Fertilizer

摘要

Production practices that increase hay yields are important for beef cattle producers in the Nebraska Sandhills. This study evaluated the responses of subirrigated meadow vegetation to fertilization with N, P, and S over a 4-yr period. A factorial array of four levels of N (0, 45, 90 and 135 kg ha-1), two levels of P (0 and 20 kg ha-1) and two levels of S (0 and 22 kg ha-1) were applied each year to the same plots, arranged in a randomized complete block design. Average dry matter yields were increased by N, P, and S. There were no fertilizer interaction effects. Yields increased quadratically as N levels increased. For each 45 kg increment of N applied from 0 to 135 kg ha-1, dry matter yield (pooled over P and S) increased 1002, 703, and 402 kg ha-1, respectively. Main effects of P and S increased dry matter yields by 4662 and 577 kg ha-1, respectively. Nitrogen uptake was increased linearly by fertilization with N, P, and S. Forage N use efficiency decreased as N fertilizer rates increased. Crude protein (CP) declined quadratically as N rates increased, but the maximum change was less than 10 g kg-1. In vitro dry matter digestibility (IVDMD) declined linearly as N rates increased. Sulfur and P did not affect either CP or IVDMD. Yield responses were sufficient to justify the use of N, P, and S to increase subirrigated meadow production. Loss of forage quality (CP and IVDMD) was not sufficient to nullify this conclusion.