Response of Maize Productivity and Resource Use Efficiency to Combined Application of Controlled‐Release Urea and Normal Urea under Plastic Film Mulching in Semiarid Farmland

Abstract

Controlled‐release urea is considered to enhance crop yields while reducing labor costs from fertilizer dressing, but the impacts can range widely depending on water availability in soil. Therefore, we conducted a 3‐yr field study to evaluate the potential role of controlled‐release urea in improving productivity and resource use efficiency of maize in semiarid areas in China. Treatments were established as two mulching modes (plastic film mulching [FM] and no mulching [NM]) and three nitrogen application modes (no nitrogen fertilizer [CK], a 1:2 ratio of controlled‐release urea to common urea [CRU], and common urea only [U]). Higher temperature and soil water content under FM treatments significantly accelerated maize growth and development, as indicated in terms of a larger leaf area index before silking, greater biomass accumulation, and greater grain yield. More robust plants with controlled‐release urea under mulching can better absorb and utilize deep soil water to increase water use efficiency (WUE). Mean shoot biomass, grain yield, and WUE during the three experimental years were 35.3, 19.0, and 12.4% higher in mulching with CRU treatments than in NM with controlled‐release urea treatments, respectively. Significant interactions existed for yield and WUE among surface mulching (SM), nitrogen fertilizer (NF), and sampling year (Y) in the three experimental years, except for SM × NF for WUE. These results demonstrate that a mixture of controlled‐release urea and U at an appropriate ratio under SM can provide a better water/temperature/nitrogen conditions for maize growth to realize relatively high yield with labor and time savings in semiarid farmland.Core Ideas Film mulching benefits topsoil temperature, soil moisture, and utilization of deeper soil water. Combining controlled‐release urea (CRU) and urea increased yield and resource use. Combing CRU and urea under plastic film increased yield and WUE. One‐time application of CRU + urea at an appropriate ratio will satisfy spring maize in dryland farming systems.