连续施用控释肥对小麦/玉米农田氮素平衡与利用率的影响

当前关于控释肥对氮素损失和作物产量影响研究比较广泛,但缺乏对控释肥长期施用的土壤氮素平衡以及相应氮素管理的研究。该试验在小麦/玉米两熟农田研究了连续施用3年控释肥后的氨挥发损失、土壤氮素残留和作物吸收规律特征。试验设5个处理:不施肥处理(CK),常量尿素(CU),优化尿素(75%常规用量,OU),常规用抑制量控释尿素(CC)和优化用量抑制控释尿素(OC)处理。试验结果表明,控释肥明显降低3个施肥时期(小麦底肥,小麦追肥和玉米底肥)的氨挥发损失。3年试验结束时,OU处理土壤剖面(0-180 cm)硝态氮显著减少,而OC处理只有深层(100 cm以下)硝态氮累积量显著减少。由于过量施肥,试验第一年所有施肥处理之间小麦和玉米产量均无显著差异,OU处理下的小麦和玉米3年平均产量显著低于其他施肥处理。OC处理的3年平均肥料表观利用率最高,其次为CC和OU处理,CU处理最低。通过本研究结果说明,控释肥对提高当前小麦/玉米农田区作物产量的效果不显著,但可有效改善肥料利用效率,并在肥料投入减少25%的情境下,能够长期保持土壤氮素平衡。

Effect of continuously appling controlled-release fertilizers on nitrogen balance and utilization in winter wheat-summer maize cropping system

Abstract: Currently, the research about the controlled-release fertilizer affecting crop yield and nitrogen loss is extensive, but it''s lacking about the soil nitrogen balance after long-term applying controlled-release fertilizer with different managing practices. This study determined ammonia volatilization, nitrogen uptake by crop and nitrite accumulation in soil with applying controlled-release fertilizer for 3 years continuously in winter wheat/summer maize cropping system in North China Plain (NCP). There were 5 treatments: no nitrogen fertilizer (CK), conventional dosage of urea (CU), optimum dosage of urea (75% of the conventional dosage, OU), conventional and optimum dosage of controlled-release fertilizer (CC and OC), respectively. The CK treatment was chosen from a long-term experiment without nitrogen lasting for 15 years, and the CU treatment was 505 kg/(hm2·a) (nitrogen amount) based on the average of the survey at the local farmlands. The results showed that ammonia volatilization was lower after the controlled-release fertilizer was applied in the 3 periods (base fertilizer for wheat, top dressing for wheat and base fertilizer for maize) in the whole growth season in a year, due to the prevention of the hydrolysis of urea by adding the inhibitor in controlled-release fertilizer, especially in the warmer condition of base fertilizer for maize. At the end of the three-year experiments, the accumulation of nitrate in soil for the OU treatment was lower significantly than the CU treatment in the whole profile (0-180 cm); while for the OC treatment the accumulation reduced only in the deep layers (below 100 cm). There were no significant differences in the yield of wheat or maize among the 4 treatments of nitrogen applied in the first year, due to the excessive fertilization in the past years. The yield of maize for OC treatment was significantly higher than that for the OU in the second year, but for wheat both in the second and the third year. In contrast, for the CC treatment, the yield of maize only in the second year was higher than the CU treatment. As for the average yield of wheat and maize in 3 years, the OU treatment was significantly lower than other 3 treatments (OC, CC and CU treatments). The average of nitrogen apparent efficiency in 3 years was the maximum for the OC treatment, followed by the CC and the CU treatments; and the CU treatment was the minimum. This study shows that the use of controlled-release fertilizer can''t increase the yield of the crop with conventional dosage applied, but can significantly improve the nitrogen apparent efficiency with reducing fertilizer input by 25%, and also can maintain the long-term soil nitrogen balance.