Applications of organic manure increased maize (Zea mays L.) yield and water productivity in a semi-arid region

•Organic manure tillage conducted at typical semi-arid region of northwestern China.•Organic manure application improved 50-150 cm soil water use.•Soil structure and fertility was improved and ensured great soil productivity.•Organic manure stably increased grain yield by 5-10%.•Water productivity increased by 3-8% under integrated effect of manure and density.

Organic manure application has been neglected in recent years, reflecting the rapid replacement with synthetic fertilizer. Exploration of the restorative effect of organic manure on the soil fertility, quality and sustainable productivity is urgently needed. A 4-year field experiment (2011-2014) investigated variation of grain yield, soil water-nutrient content and plant growth in a local cultivar (Zheng Dan 958) of maize (Zea mays L.) at three planting densities with extra organic manure application in a semi-arid region of Northwestern China. Soil water content in 0-50 cm and below 150 cm soil profile was maintained stably at 25% and 18% under organic manure application over four consecutive years, and soil water use in the depth of 50-150 cm was improved. Organic manure helped residual soil nutrient mineralization after harvest with 25%, 198% and 41% increases in total nitrogen (N), available phosphorus (P) and soil organic matter (SOM) over three years respectively. Adequate content of N, P and SOM after maize harvest played an important role for stable high yield in the next season. Consequently, the biomass allocation into shoot and grains was optimized and presented as a slight increase in harvest index (HI). Based on the improvement of water-nutrient status in manured soil, maize water productivity (WP) increased by 3-8%, which positively associated with the yield increase by 5-10% at high planting density. Organic manure could be used to improve soil environment, promote yield and WP in maize in dryland agriculture.