寒旱区不同秸秆还田方式对土壤团聚体稳定性和有机碳组分含量的影响

Effects of different straw returning methods on soil aggregate stability and organic carbon content in cold and arid regions

为了明确春玉米秸秆还田对低温缺水条件下农田土壤团聚体及其有机碳组分的影响,并为冀西北寒旱区春玉米秸秆还田方式提供科学依据,田间设置秸秆还田翻耕(JF)、秸秆还田旋耕(JX)、大垄轮播秸秆还田(JL)3种还田方式,以秸秆不还田为对照(CK),分析秸秆还田方式对土壤不同粒径团聚体分布、稳定性及有机碳组分含量的影响。结果表明:在0~20 cm土层,各还田方式均能显著提高1.00~2.00 mm团聚体占比,JX处理显著提高>5.00 mm团聚体占比。JX处理土壤团聚体平均重量直径(MWD)最高,团聚体稳定性较强,JL和JX处理显著提高2.00~5.00 mm团聚体占比,JL处理土壤团聚体几何平均直径(GMD)较高。各还田方式对土壤MWD和GMD分别提高了10.32%~15.46%和16.23%~18.35%,均能增加土壤团聚体稳定性。土壤各粒径团聚体有机碳含量在42.88~54.72 g·kg^(-1)之间,JL处理显著提高2.00~5.00、0.50~1.00 mm团聚体有机碳含量,增幅大于其它两种还田方式。各还田方式土壤各粒径团聚体活性有机碳含量在4.18~8.29 g·kg^(-1)之间,各团聚体活性有机碳含量均高于CK;秸秆还田均能提高1.00~2.00、0.50~1.00 mm团聚体黑碳含量,JF和JX处理提高>5.00、2.00~5.00 mm团聚体黑碳含量;JL处理提高>5.00、2.00~5.00、1.00~2.00、0.25~0.50 mm团聚体腐殖质碳含量。各还田方式对0~20 cm土层有机碳含量提高幅度高于20~40 cm土层,CK和JF处理团聚体腐殖质碳含量20~40 cm土层高于0~20 cm土层。CK、JF和JX处理>5.00、2.00~5.00、1.00~2.00 mm团聚体黑碳含量在0~20 cm土层最高。综合分析冀西北部寒旱区适宜采用春玉米大垄轮播秸秆还田方式。

In order to clarify the impact of returning spring corn straw on soil aggregates and their organic carbon components under low temperature and water scarcity conditions in farmland,and to provide scientific basis for the method of returning spring corn straw to farmland in the northwest cold and arid region of Hebei,three methods of returning straw to farmland were set up in field experiment,namely,returning straw to farmland through plowing(JF),returning straw to farmland through rotary tillage(JX),and returning straw to farmland through large ridge rotation(JL).Using no straw returning to farmland as control(CK),the effects of straw returning methods on the distribution,stability and organic carbon component content of soil aggregates with different particle sizes were analyzed.The results showed that in 0-20 cm soil layer,all returning methods significantly increased the proportion of 1.00-2.00 mm aggregates,while JX treatment significantly increased the proportion of>5.00 mm aggregates.The average weight diameter(MWD)of soil aggregates under JX treatment was the highest,and the stability of aggregates was strong.JL and JX treatments significantly increased the proportion of 2.00-5.00 mm aggregates,while JL treatment had a higher geometric mean diameter(GMD)of soil aggregates.Each returning method increased soil MWD and GMD by 10.32%-15.46%and 16.23%-18.35%,respectively,which could increase soil aggregate stability.The organic carbon content of soil aggregates with different particle sizes ranged from 42.88-54.72 g·kg^(-1).The JL treatment significantly increased the organic carbon content of aggregates by 2.00-5.00 and 0.50-1.00 mm,with an increase greater than the other two returning methods.The active organic carbon content of soil aggregates with different particle sizes under different returning methods ranged from 4.18 to 8.29 g·kg^(-1),and the active organic carbon content of each aggregate was higher than that of CK.Returning straw to the field increased the black carbon content of aggregates of 1.00-2.00 and 0.50-1.0 mm,while JF and JX treatments increased the black carbon content of aggregates of>5.00 and 2.00-5.00 mm.JL treatment increased the carbon content of aggregate humus of>5.00,2.00-5.00,1.00-2.00,and 0.25-0.50 mm.The increase in organic carbon content in 0-20 cm soil layer by various returning methods was higher than that in 20-40 cm soil layer,while the carbon content of aggregate humus in 20-40 cm soil layer treated with CK and JF was higher than that in 0-20 cm soil layer.The black carbon contents of aggregates>5.00,2.00-5.00,and 1.00-2.00 mm with CK,JF,and JX treatments were the highest in 0-20 cm soil layer.Based on comprehensive analysis,it was suitable to adopt the method of rotating spring corn in large ridges and returning straw to the field in the cold and arid areas of northwest Hebei.