Optimizing Irrigation and Fertilization Coupling to Balance the Improvement of Yield and Water Use Efficiency of Summer Maize

Abstract

【Background and objective】 Water scarcity and non-point pollution are double whammies facing agricultural production in north China. Optimizing irrigation and fertilization to make agriculture greener and more energy-efficient is hence critical to sustaining food production. Henan province is one of the key agricultural production bases in China, and agriculture in most regions across the province relies on irrigation. The objective of this paper is to analyse how to improve economic and productive benefits by balancing irrigation and fertigation amount in these regions. 【Method】 Summer maize was taken as the example as it is a staple crop in the province. We considered three irrigation treatments and three fertilizations. Based on data obtained from irrigation and fertilization experiments, we first derived a regression model to quantify the dependence of crop yield and water use efficiency (WUE) on irrigation amount and fertilization amount, from which we further analysed the single-factor effect, marginal effect and coupling effect of irrigation and fertilization amounts on yield and WUE of the crop. The optimal irrigation and fertigation amounts for balancing the yield and WUE of the crop was solved using the non-dominated sorted genetic algorithm-II (NSGA-II) method. 【Result】 ①With the increase in irrigation and fertigation amounts, the yield and WUE of the crop increased first followed by a decline when their application rates exceeded their respective threshold values. ②Overall, the effects of soil water on yield and WUE of the crop were greater than that of fertilizer. ③ Water and fertilizer coupling positively impacted on maize yield and its WUE. 【Conclusion】 The optimal coupling of water and fertilizer application obtained in this paper for maize production in Henan province is as follows: irrigation amount 848.24 m3/hm2, ferlization amount 192.66 kg/hm2. Under these conditions, the maize yield was 10 667.52 kg/hm2 and its associated WUE was 3.11 kg/m3.

Keywords

• maize
• water and fertilizer coupling
• bi-objective optimization
• non-dominated sorting genetic algorithm-ii
• matching scheme