秸秆还田对土壤水稳性团聚体及其碳分布的影响

Effects of Straw Turnover on Soil Water-Stable Aggregates and Soil Carbon Distribution

研究秸秆还田方式对土壤水稳性团聚体组成、稳定性和有机碳分布的影响,为东北旱作区作物生产及秸秆还田制度提供参考。田间试验始于2015年,设置旋耕秸秆还田(RT)、旋耕秸秆不还田(CK1)、翻耕秸秆还田(PT)及翻耕秸秆不还田(CK2) 4个处理,分别对2017年收获后土壤的样品不同粒级团聚体质量分数、稳定性、有机碳(SOC)分布以及近3 a的玉米产量进行测定。结果表明:秸秆还田处理提高土壤表层各粒径团聚体的SOC含量,促进大团聚体的形成与稳定。在0～10 cm土层中,相同耕作措施下,RT处理SOC含量比CK1处理的提高13. 90%(P <0. 05),PT处理比CK2处理提高9. 29%(P <0. 05)。不同耕作措施下,RT处理与PT处理相比,大团聚体质量提高22. 05%,团聚体平均重量直径(MWD)提高7. 78%,粉+黏团聚体含量降低16. 81%(P <0. 05)。比较不同年份玉米产量发现,降水量不同产量不同,2017年降水量低于2016年,2017年各处理产量均低于2016年,但处理间降幅不同,RT和PT处理降幅(8. 57%、9. 72%)低于CK1和CK2处理(10. 84%、12. 13%),说明秸秆还田处理有稳产作用,其中RT处理趋势较明显。因此,在东北春玉米旱作区秸秆全层还田条件下,旋耕秸秆还田促进土壤水稳性团聚体形成,提高土壤SOC含量,可为玉米生产在不同降水年份提供稳产保障。

In this study,the effects of crop residue turnover on the composition and stability of soil water-stable agglomeration and the distribution of soil organic carbon in aggregates were investigated for giving a reference to crop production and crop residue turnover in the semiarid areas in northeast China. A field experiment including rotary tillage and plough tillage with/without crop residue incorporation treatments( RT,CK1,PT and CK2) was started in 2015. The purposes of this study were to explore the effects of tillage and straw management practices on the ratio of soil aggregates with various sizes,stability of soil water-stable agglomeration,distribution of soil organic carbon( SOC) in 2017 and maize yield from 2015 to 2017. Our results indicated that the residue incorporation could be used to significantly increase the SOC content by 13. 90%( RT) and 9. 29%( PT),respectively,in 0-10 cm soil layer compared with those without residue incorporation( P < 0. 05). Compared with PT,the content of waterstable aggregates( > 2 mm) and average weight diameter of aggregates( MWD) were significantly increased by22. 05% and 7. 78%,respectively,while the content of water-stable aggregates( < 0. 053 mm) was significantly decreased by 16. 81% by RT management( P < 0. 05). In addition,RT significantly enhanced the SOC of waterstable aggregates in topsoil,and the most improvement was found in the water-stable aggregates > 2 mm( P <0. 05). There was no significant difference in maize yield in 2016 and 2017. Compared with the yield in 2016,the yield reduction from RT and PT treatments( 8. 57%-9. 72%) was lower than that from CK1 and CK2( 10. 84%-12. 13%) in 2017. Therefore,the rotary tillage with residue returning practice in dryland farming is recommended with benefits of promoting soil water-stable aggregate formation and increasing SOC content so that give a stable yield for maize production regardless of precipitation variation in northeast China.