Effect of nitrogen application on yield and quality of silage corn after forage legume-grass
Decomposition of forage legume-grass (FLG) sods after turnover will supply N to the next corn (Zea mays L.) crop. For optimum economic grain production typically a starter N application is sufficient. However, the impact of eliminating sidedress N on yield and quality of silage corn in the year after sod turnover (FYC) is not well documented and little is known about the effects of timing of sod turnover (fall or spring) or sod composition (percentage legume) on N fertilizer needs of FYC. In 2005 and 2006, 13 on-farm and three research station N trials were conducted throughout New York (NY) to determine (i) N needs for optimum yield and quality of FYC and (ii) the impact of FLG composition and timing of sod kill on the likeliness of an economic N fertilizer response. On-farm trials included four sidedress N rates (0, 56, 112, and 168 kg N ha–1) with a small, banded starter application (34 kg N ha–1 maximum). The three research sites also contained a no starter control. Eliminating the starter resulted in significantly lower yields while sidedress N did not increase yield at any of the 16 sites. Nitrogen application increased crude protein (CP) levels but did not affect other silage quality parameters or estimated milk production. The increase in CP came at great economic (fertilizer) and environmental (low apparent N recovery) costs. We conclude a small starter application is sufficient for optimum yield and quality of FYC regardless of timing of sod turnover or its composition.