Effects of fertilization on soil moisture and maize yield in rainfed farmland with ridge mulching-furrow planting system

Objectives Ridge mulching-furrow planting is a high-efficiency and water-saving cultivation mode widely used in arid northwest China. To understand the effects of fertilization on crop yield, we conducted a five-year field experiment in Guyuan of Ningxia Hui Autonomous Region and analyzed the effects of different fertilization treatments on soil moisture and maize yield.

Methods Ridge mulching-furrow planting system, as a rainwater harvesting system, was adopted in this experiment. The four different fertilization levels in this study were: no fertilizer control (CK); low fertilizer rate (N 150 kg/hm², P₂O₅ 75 kg/hm²); medium fertilizer rate (N 300 kg/hm², P₂O₅ 150 kg/hm²) and high fertilizer rate (N 450 kg/hm², P₂O₅ 225 kg/hm²). During the key growing stages of maize, soil samples were collected in 0–200 cm depth for determination of water content, water consumption of farmland, water use efficiency (WUE), while maize yield was assessed at maturity stage.

Results The water consumption of farmland and dry matter accumulation (DM) of maize increased with the increase in fertilizer amount, regardless of annual rainfall. Compared to CK, high, medium and low fertilizer treatments increased water consumption by 8.6%, 7.7% and 5.3%, respectively, while they increased dry matter accumulation by 38.3%, 35.8% and 31.2%, respectively. In general, the medium fertilizer treatment had the highest average grain yield (11.4 t/hm²) with the lowest yield variation coefficient (12.9%). In wet year, low fertilizer treatment had higher maize yield and water use efficiency than high and medium fertilizer treatments did, while in median water year and drought year, medium fertilizer treatment had higher grain yield and water use efficiency.

Conclusions In semi-arid area, the effects of fertilizer application rate on yield and water use efficiency under the ridge-furrow rainfall harvesting planting relies on rainfall. In wet year, lower fertilizer rate (N 150 kg/hm², P₂O₅ 75 kg/hm²) could achieve higher yield and WUE, while in normal and drought year, middle level of fertilization rate (N 300 kg/hm², P₂O₅ 150 kg/hm²) is recommended. High fertilizer rate (N 450 kg/hm², P₂O₅ 225 kg/hm²) could reduce soil water.