Reducing Nitrogen Inputs Improves the Production of Maize Grain and Forage

Abstract

ABSTRACT Aiming to optimize the nitrogen (N) application rate during maize production and to improve the production process, we carried out a 2-year field study included 5 N application rates and five recommended production patterns (maize grain (P1); maize grain and straw (P2); the whole maize plant (WMP) forage (P3); grain, straw and milk (P4); WMP forage and milk (P5)). The results showed that reducing N application rate from 400 to 300 kg N ha−1 maintained the maize yield and the forage quality for different patterns. Compared to 400 kg N ha−1, 300 kg N ha−1 increased the economic profit and the economic efficiency of N fertilizer (EEN) of all patterns. Compared to the optimal N rate with the same pattern, the 75% of optimal N rate caused in a 2% decrease in economic profits, but saved N fertilizer by 25% and increased EEN by 30%; the 75% of optimal N rate saved N fertilizer by 50% and increased EEN by about 40%, but caused in a 8–9% decrease in economic profits. Therefore, the 75% of optimal N rate was optimal in improving maize production. When the economic profits from the five patterns were optimized based on regression equations, ranking the optimal N rates and economic profits in increasing order led to the following result: P1 < P2 < P3 < P4 < P5. The extending maize production chain from P1 to P5 improved economic profits, and increased the optimal N rate, improving the productivity of N fertilizer.