Release durations and suitable application patterns of coated urea on winter wheat in sandy loam soil

【Objectives】 Sandy loam soil is characterized by high permeability and low nutrients and water retention capacity. N loss through leaching is often occurred during winter wheat growing season in this type of soil. The effect of water-borne polymer-coated urea fertilizers was studied with different nutrient release durations and application patterns in order to improve winter wheat (Triticum aestivum L.) yield and N fertilizer use efficiency. 【Methods】 A field experiment of three water-borne polymer-coated urea fertilizers with different nutrient release duration (30, 60 and 90 d, hereafter namely PCU30, PCU60 and PCU90) and different application patterns once 12 cm underneath the seed (T1), once 3 cm away from and 5 cm underneath the seed (T2), once 10 cm away from and 5 cm underneath the seed (T3) was conducted. The yield of straw and grain were measured, the N contents were determined at harvest.【Results】 The PCU60 presented the highest yield among those fertilizers and the effect was greater when applied away from the wheat seed than applied directly underneath it. The highest yield was 8661 kg/hm2 in T2 of PCU60 which increased by 6.5% compared with local farmer fertilization practice (FFP, urea application at 40%-30%-30%). The highest N use efficiency was 53.7% in T2 of PCU60 and was 17.3% higher than that in local fertilization practice. Regardless of fertilizer application patterns, yield and N use efficiency were lower and soil NO-3 concentration was higher in PCU90 than in local practice, thus PCU90 was not suitable for local agricultural management. 【Conclusions】 The PCU60 applied 3 cm away from and 5 cm underneath the wheat seed could significantly decrease labor input and increase wheat yield, so it is a suitable coated fertilizer in the sandy loam soil in Jiangyan Country.