浙江省稻田系统秸秆还田问题及对策

秸秆还田是实施肥药减施及有机养分替代的主要技术。稻-麦轮作是浙江北部和中部稻区的主要栽培模式,稻-油和稻-稻模式则主要分布在浙江中部和南部稻区。调查表明,浙江稻区不同栽培模式的秸秆还田与耕作方式主要有:双季稻田秸秆翻耕还田,稻-麦(油)轮作水稻秸秆覆盖还田,以及稻-麦(油)轮作水稻季的4种秸秆还田耕作方式——麦(油)秸秆覆盖还田免耕水稻直播方式、麦(油)秸秆还田浅耕水稻直播方式、麦(油)秸秆还田深耕水稻插秧方式、麦(油)秸秆还田深耕水稻直播方式。不同耕作及还田方式各有利弊,但同时存在秸秆量大、还田困难,肥料配施没有定量计算方法,病虫害加剧,土壤水分需要科学管理,农机需要合理选择与操作等问题。通过调查研究,参考已有的研究技术资料,针对秸秆还田存在的问题进行分析与总结,提出以下对策。1)采取方式轮换措施调和不同耕作类型及不同秸秆还田方式产生的不足。2)中等肥力农田以单季秸秆还田量5~6 t·hm^-2、全年秸秆还田量10~12 t·hm^-2比较适宜,超过的秸秆量建议通过综合利用方式加以解决。3)肥料配施采取以氮肥全季调施、前期适当增施,钾肥适当减施为主的秸秆还田施肥策略。4)病虫害防治采取提前翻耕、秸秆深埋、淹水闷田的措施。5)水分管理以易于机械耕作和秸秆还田后保持土壤湿度促进秸秆腐解为原则,晚稻提倡干湿交替的灌溉管理方式。6)机械类型应选择带有秸秆切碎装置的收割机,耕作机械要保证翻埋深度,以实现稳定与均匀的还田作业。

Problems and countermeasures of straw returning in paddy field system in Zhejiang Province

Straw returning is the main measure to reduce fertilizer application and replenish organic nutrients in soils. The rotation system of rice-wheat is mainly applied in northern and central area in Zhejiang, while rice-oilseed rape and rice-rice are applied in southern and central Zhejiang. There are many problems about the application of crop straw returning due to the diversity of rotation system in paddy field systems in Zhejiang. The main measures applied of straw returning under different rotation in Zhejiang consist of the plowing of rice straw for rice-rice rotation, mulching with rice straw for rice-wheat (or oilseed rape), and the plowing and mulching of wheat or oilseed rape straw for rice-wheat or rice-oilseed rape, which specifically includes the returning of wheat or oilseed rape straw without tillage and direct seeding of rice, shallow-tillage and returning of wheat or oilseed rape straw with direct seeding of rice, deep-tillage and returning of wheat or oilseed rape straw with simultaneous rice transplanting, and deep-tillage and returning of wheat or oilseed rape straw with direct seeding of rice. Suggestions to better utilize the measure of straw returning were proposed based on previous research, investigation data and analysis into current problems under different cultivation modes. 1) Specific rotation methods were suggested to reconcile the deficiencies of these straw returning methods. 2) The amount of straw returning was suggested to be 5-6 t·hm^-2 for a single crop season and 10-12 t·hm^-2 for the entire year. 3) Fertilizer was applied following a straw returning strategy of applying appropriate additional nitrogen fertilizer during the prophase and regulating nitrogen fertilization during full season, and reducing application rate of potash fertilizer. 4) Diseases and pest control should be conducted via early plowing, deep straw burial, and field flooding. 5) Water management should follow the principles of easy cultivation, appropriate soil moisture content to promote the decomposition of straw after returning to the field, and alternative irrigation management mode of dry and wet during the late rice phase. 6) For the selection of the mechanical type, a harvester with a straw shredding device was suggested, and the tillage machine should ensure sufficient burial depth to achieve stable and uniform returning operation.