施氮和秸秆还田对晚播小麦养分平衡和产量的影响

Effects of nitrogen application rates and straw returning on nutrient balance and grain yield of late sowing wheat in rice-wheat rotation

在大田条件下,研究了水稻秸秆还田和施氮量对晚播小麦产量、养分积累、秸秆养分释放及养分平衡的影响.结果表明:水稻秸秆还田并配施适当的施氮量有利于提高晚播小麦籽粒产量.晚播小麦全生育期的干物质、氮、磷、钾积累量均随施氮量增加而显著增加,相同施氮量(270 kg N·hm-2)下,秸秆还田处理的干物质、磷、钾积累高于不还田处理,氮积累则呈相反趋势.随着施氮量增加,秸秆腐解和养分释放率增加,且拔节后秸秆养分释放量占总释放量的比例降低;随生育进程的推进,秸秆的干物质、磷、钾释放量呈倒"N"型变化趋势,而氮释放量则呈"V"型变化趋势.计算养分表观平衡结果表明,秸秆还田并增加施氮量,养分总盈余量显著升高;在获得较高产量的施氮条件下,氮、钾素显著盈余,磷素投入较为合理.晚播小麦实行秸秆还田后,可适当增加氮肥用量至257 kg·hm-2,并减少钾肥投入.

Field experiments were conducted to study the effects of nitrogen application rates and straw returning on grain yield,nutrient accumulation,nutrient release from straw and nutrient balance in late sowing wheat. The results showed that straw returning together with appropriate application of nitrogen fertilizer improved the grain yield. Dry matter,nitrogen,phosphorus and potassium accumulation increased significantly as the nitrogen application rate increased. At the same nitrogen application rate（ 270 kg N·hm^-2）,the dry matter,phosphorus and potassium accumulation of the treatment with straw returning were higher than that without straw returning,but the nitrogen accumulation was lower. Higher-rate nitrogen application promoted straw decomposition and nutrient release,and decreased the proportion of the nutrient released from straw after jointing. The dry matter,phosphorus and potassium release from straw showed a reverse ‘N＇type change with the wheat growing,while nitrogen release showed a ‘V＇type change. The nutrient surplus increased significantly with the nitrogen application rate. At the nitrogen application rate for the highest grain yield,nitrogen and potassium were surplus significantly,and phosphorus input could keep balance. It could be concluded that as to late sowing wheat with straw returning,applying nitrogen at 257kg·hm^-2and reducing potassium fertilizer application could improve grain yield and reduce nutrients loss.