Evaluation of Narrow‐Row Corn Forage in Field‐Scale Studies

Abstract

Some dairy producers in the northeastern USA grow corn (Zea mays L.) in narrow rows at high plant densities and N fertility. We evaluated first‐year, second‐year, and continuous corn in field‐scale studies at 0.76‐ and 0.38‐m row spacings at recommended densities (≈85000 plants ha−1) and N fertility (≈165 kg ha−1) and at 0.38‐m spacing at high densities (≈100000 plants ha−1) and N fertility (≈225 kg ha−1) in 1998, 1999, and 2000 to determine if narrow‐row corn forage requires high densities and N fertility for optimum yield and quality. Narrow‐row corn at high vs. recommended densities and N fertility had similar soil NO3–N concentrations in the upper 0.3‐m depth and whole‐plant N concentrations at the sixth leaf stage of corn (V6) as well as similar ear‐leaf N concentrations at silking in eight of the nine site‐year comparisons. All treatments were above critical concentrations for soil NO3–N concentrations (>25 mg kg−1), whole‐plant N concentrations (>35 g kg−1), and ear‐leaf N concentrations (>25 g kg−1, except in the cool 2000 season). Consequently, narrow‐row corn at high vs. recommended densities and N fertility had similar dry matter yield and quality in eight site‐year comparisons. Furthermore, narrow‐row corn at high vs. recommended densities and N fertility had greater residual soil NO3–N concentrations in three site‐year comparisons. We recommended that dairy producers in the northeastern USA grow narrow‐row corn forage at recommended plant densities and N fertility.