留茬高度与秸秆粉碎程度对稻-油产量和土壤养分的影响

Effects of stubblein height and grinding degree during straw application on crop yield and soil nutrients under rice-rapeseed rotation

优化水稻-油菜轮作模式下秸秆还田方式,为秸秆还田机械化提供技术参数,为作物高产和土壤培肥的协同发展提供理论支撑。2017—2019年在长江中游稻-油轮作区开展秸秆还田田间试验,共设置4个处理,分别为:不留茬+细粉碎、留中茬+细粉碎、留中茬+粗粉碎、留高茬+细粉碎,对比分析不同留茬高度和秸秆粉碎程度对作物生长与产量,以及作物生长过程中土壤养分含量的影响。结果表明:水稻和油菜均表现为留茬越高越有利于提高基本苗,且秸秆粗粉碎基本苗高于细粉碎,但不同留茬高度和秸秆粉碎程度对作物苗期SPAD值未表现出明显影响。第一季作物产量均是以留中茬高于不留茬和留高茬(水稻和油菜产量增幅分别为7.1%~21.1%和2.4%~4.6%)、细粉碎高于粗粉碎(增幅分别为11.7%和12.9%),但第二季作物产量处理间差异均未达到显著水平。作物生育期内土壤养分含量整体变化为先降低、到收获期有略微升高的趋势;在作物生育前期,水稻季不留茬+细粉碎、油菜季留中茬+粗粉碎可提高土壤铵态氮和硝态氮含量;在作物收获期,水稻和油菜季均是以留中茬+粗粉碎处理土壤有效磷和速效钾含量较高。因此,在作物产量反映和土壤养分变化的基础上,综合考虑秸秆还田作业成本与能耗,本研究推荐长江中游稻-油轮作周年秸秆还田方式为水稻留中茬、油菜留中茬或高茬,秸秆粉碎程度均为细粉碎。

The effects of straw returning on crop yield and soil nutrients under rice-rapeseed rotation were studied,so as to provide technical parameters for the mechanization of straw returning,and provide reference for the coordinated development of high yield and soil fertility.In this study,the comparative positioning experiment of straw returning to the field was carried out during 2017—2019 in Wuxue city,Hubei province.Field experiments of straw returning were conducted in the rice-rapeseed rotation farming area of the middle reaches of the Yangtze River from 2017 to 2019.Four treatments were set up:no stubblein+fine grinding,middle stubblein+fine grinding,middle stubblein+coarse grinding and high stubblein+fine grinding.The effects of straw returning to the field on the growth and yield of rice and rapeseed,and soil nutrients under different stubblein heights and grinding degrees were studied.The results showed that the higher the stubblein height was,the better it was to improve the basic seedlings,and it was higher in coarse grinding than that in fine grinding both in rice and rapeseed seasons.Different stubblein height and straw grinding degree had no significant effect on the SPAD value at seedling stage.In the first season,the yield with medium stubble was higher than that without stubble and with high stubble(the yield increment of rice and rapeseed was 7.1%-21.1%and 2.4%-4.6%,respectively),and that of fine grinding was higher than that of coarse grinding(the increment was 11.7%and 12.9%).However,the yield difference in the second season between the treatments was not significant.During the crop growth period,the soil nutrient content decreased first and increased slightly in the harvest period.In the early stage of crop growth,no stubblein+fine grinding in rice season and middle stubblein+coarse grinding in rapeseed season increased the content of ammonium nitrogen and nitrate nitrogen.In the harvest period,the contents of available phosphorus and available potassium in both rice and rapeseed seasons were higher in middle stubblein+coarse grinding.Therefore,on the basis of yield response and soil nutrient change,considering the operation cost and energy consumption of straw returning to the field,this study recommends that the annual straw returning mode of rice-rapeseed rotation in the middle reaches of the Yangtze River should be rice with middle stubblein,rapeseed with middle or high stubblein,and the straw grinding degree should be fine grinding.