The effect of irrigation quota on straw decomposition, nitrogen release, and maize nitrogen uptake

Returning straw to the field can increase soil organic matter content, improve soil physical and chemical properties, enhance soil biological activity, and thus improve soil fertility. However, returning straw to the field has problems such as slow decomposition rate and delayed nutrient release. Reasonable water management is one of the important measures to improve the effectiveness of returning maize straw to the field. To explore soil moisture management measures suitable for maize straw decomposition, nitrogen release, maize yield increase, and efficient water utilization, a 2-year study was conducted in a movable rain shelter. Set three irrigation quotas, namely 200 mm, 350 mm, and 500 mm (represented by I 200, I 350, and I 500), and two straw return methods, straw returning and not returning to the field were represented by SR and CK, respectively. The experimental results showed that the decomposition rate and nitrogen release rate of I 350 were significantly greater than those under the other irrigation treatments. There was no significant difference in plant nitrogen uptake or maize yield between I 350 and I 500, but the values were significantly greater than those in I 200. The water use efficiency of I 350 treatment group was significantly greater than that of I 500 treatment group. Returning straw to the field has only a compensatory effect on the nitrogen uptake and transport of plants under some low irrigation levels. Under these experimental conditions, I 350 was more conducive to straw decomposition, straw nitrogen release, maize nitrogen uptake, maize yield increase, and efficient water use. This study can provide a theoretical reference for soil moisture management under straw return conditions in semi-arid areas of Jilin Province, China.