Timing of Semi-Solid Dairy Manure Applications On Orchardgrass.

Perennial grasses have the potential to greatly alleviate nutrient management problems on dairy farms. Application rate and timing, and manure consistency need to be controlled to minimize the possibility of malfermented grass silage and to minimize environmental risks. We studied the impact of semi-solid dairy manure application rate and timing on yield and nutritive value of orchardgrass (Dactylis glomerata L.). Manure was applied at spring greenup, and after all three harvests in seven treatment combinations, not exceeding 22.4 Mg/ha/application during the growing season. The recommended rate of commercial N fertilizer was also included as a treatment and all treatments were applied for five growing seasons. A three-cut system was utilized, producing suitable forage for lactating dairy cows for cuts 1 and 2. Average dry matter (DM) yields for total seasonal manure applications of 44.8, 67.2 and 89.6 Mg/ha were 7019, 7888, and 9104 kg/ha, respectively. There was no significant effect of timing of manure applications on total DM yield, although there was a tendency for lower yields when manure was fall-applied only. Manure applied at the seasonal rate of 89.6 Mg/ha resulted in greater DM yields than recommended commercial N fertilization by the second year of the study. Neither application rate nor timing of manure application had an impact on forage nutritive value. Phosphorus and potassium buildup occurred primarily in the top 20 cm of soil, and was related to quantity of manure applied. We conclude that from a forage yield and nutritive value standpoint, timing of seasonal manure applications to orchardgrass is not a critical issue.