Leaf nitrogen sufficiency level guidelines for midseason fertilization in corn

Abstract

Improving N management guidelines in corn (Zea mays L.) production systems can reduce fertilization costs and potential negative environmental impacts. This study was conducted to assess the effectiveness of leaf nitrogen (LN) concentration as a tool to improve midseason N management in corn production. The experiment was conducted on 8 site-years with furrow irrigation. There were 11 N fertilization regimes with season total N rates ranging from 0 to 257 kg N ha−1. Split-applications were made at pre-plant, the 10th collared leaf stage (V10), the 12th collared leaf stage (V12), and tasseling (VT). The uppermost fully collared leaves were sampled at V10 and V12, and ear-leaves were sampled at VT. Grain yields ranged between 1.6 and 20.7 Mg ha−1, averaging 12.5 Mg ha−1. Relative grain yield (RGY) was positively associated with LN at V10, V12, and VT. Between V10 and VT, a single regression combining data over growth stages was developed between RGY and LN (r2 =.82, P value 30.4 g N kg−1. This relationship can be used to improve midseason N fertilization by preventing excessive N fertilization when LN is >30.4 g N kg−1, or by triggering additional N fertilization when LN is <30.4 g N kg−1.