玉米秸秆“富集深还”与土壤亚表层培肥

摘要

Subsoil often suffers from "organic matter hunger" because of the long term shallow tillage and less organic material returning.The over-tight and poor soil physical properties makes it necessary to find a simple and effective method to break up the plow pan and add organic matter to the hunger soil.In this paper,the three existing deep incorporation methods of corn stover were summarized briefly,and the concept of corn stover enrichment and deep incorporation (CSEDI) was introduced.In CSEDI,the whole-harvested corn straw is collected onto belts,then the special tube plough is used to embed straw into the 20-40 cm depth of subsoil by wind power injection.The soil layer will keep in original order,the following year's planting would not be disturbed.CSEDI simulation test showed that after straw was embedded into soil for 330 days,the decomposition rate was above 65％,the residual straw became humified and soil organic carbon content was increased by 10％-15％,the arable layer thickness increased from the original 15-18 cm to 30-35 cm.The H/C and hydrophilic ratio of humic acid were also improved.The CSEDI was not found causing the reduction of maize yield in the second year,on the contrary,achieved about 5％ of increase than that of traditional cultivation.These results proved that with the CSEDI,the full amount of corn stover could be returned to the field year by year,the alternative belt-corporation of straw made the separated planting and returning come to truth.This method was also proved to be effective to break up the plow pan and increase subsoil organic matter content quickly.%由于长期浅耕,土壤亚表层不仅缺乏有机质,还过于紧实,急需找到一种简单而有效的快速松土培肥方法.本文简要总结了已有3种秸秆还田模式的优缺点,重点介绍了秸秆“富集深还”技术及田间操作要领,以及采用该技术还田的秸秆的分解速率和亚土层培肥效果.富集深还,即将玉米联合收割机抛洒在地表的秸秆,按条带大比例富集,使用专用筒式犁具,以风力注入的方式埋入土壤亚表层(20-40 cm).这种模式的最大特点是不扰动土层顺序、不影响第二年种植.秸秆埋置模拟试验表明,秸秆还田330天时,其分解率就达到65％以上,剩余秸秆腐殖化,使土壤有机碳含量增加10％～15％,土壤耕层由原来的15-18 cm增加到30-35 cm.秸秆深还对腐殖物质结构特征没有产生不良影响,对H/C、亲水性等指标还有改善作用,促使黑土胡敏酸结构简单化和年轻化.秸秆深还没有引起第二年玉米产量降低.因此,采用该方法,秸秆能够连年全量还田,实现了种还分离(种植条带与秸秆深埋条带分离)与免耕播种的有效结合,可打破犁底层,并快速提升犁底层土壤有机质含量,为土壤亚表层快速培肥及肥沃耕层构建提供技术手段.