Estimation of Critical Nitrogen Concentration Based on Leaf Dry Matter in Drip Irrigation Spring Maize Production in Northern China

The application of nitrogen (N) fertilizer not only increases crop yield but also improves the N utilization efficiency. critical concentration (Nc) can be used to diagnose crops’ nutritional status. Nc dilution curve model maize was calibrated with leaf dry matter (LDM) as indicator, and performance for diagnosing status further evaluated. Three field experiments were carried out in two sites between 2018 2020 Ningxia Hui Autonomous Region a series levels (application from 0 450 kg ha?1). Two spring cultivars, i.e., Tianci19 (TC19) Ningdan19 (ND19), utilized experiment. results showed that negative power function relationship existed LDM (LNC) under drip irrigation. equation divided into parts: when < 1.11 t ha?1, constant value 3.25%; > 3.33LDM?0.24. LDM-based well distinguish data on N-limiting non-N-limiting maize, which independent varieties, growing seasons, stages. Additionally, nutrition index (NNI) had significant linear correlation relative (RLDM). This study revealed could accurately identify NNI thus, robust reliable tool maize.