玉米秸秆还田培肥土壤的效果

辽北地区玉米根茬还田、秸秆直接还田或间接还田的3年微区培肥试验研究结果表明，无机肥的增产效果特别明显，而施有机物料，更主要的作用是改善土壤的物理、化学性质、培肥地力，与无肥对照相比，有机无机肥料配合施用可使土壤有机质提高3．06％－27．78％，各有机物料对土壤有机质提高的顺序依次为100％秸秆＞50％秸秆＞土粪＞牛粪＞33％秸秆＞根茬。在含C量相等的条件下，秸秆对土壤有机质的保持和提高好于土粪，土粪好于牛粪。同时，与单施化肥比，有机无机肥料配合施用可使土壤易氧化有机质增加10．91％－20．67％，使浸提腐殖酸提高1．43％－14．28％，使结合态腐殖酸的松／紧比值提高0．07－0．19，HA／FA比值提高0．07－0．24，并且能改善土壤的N、P、K营养状况、土壤水分和土壤孔隙状况，这标志着土壤有机质活性的提高和土壤肥力状况的改善。因此，应该大力提倡玉米秸秆秋季直接还田，其最佳施入量应为当年生产量的30％－50％。

Effect of returning corn straw into soil on soil fertility

Three-year field micro-plot experiment was conducted to study the effect of applying corn root stubble, corn straw, and the ordure of cattle fed with corn straw to improve soil fertility in northern Liaoning province. The results showed that chemical fertilizers could significantly increase the corn production, while organic fertilizers mainly improved the soil physical and chemical properties so as to increase soil fertility. In comparison with no fertilizer treatment, combination of chemical fertilizers and organic materials could increase soil organic matter by 3.06%-27.78%. The increments of soil organic matter by using different organic materials were in order of 100% corn straw > 50% corn straw > mixture of cattle ordure and soil > cattle ordure > 33% corn straw > corn root stubble. For maintaining and increasing soil organic matter, corn straw was better than mixture of cattle ordure and soil, and secondly better than cattle ordure if they contained the same carbon content. In addition, comparing with applying chemical fertilizers only, combination of chemical fertilizers and organic materials increased soil labile oxidization organic matter by 10.91%-20.67%, increased extractable humic acid by 1.43%-14.28%, raised slack/stable ratio of bonded humus by 0.07-0.19, and raised HA/FA ratio by 0.07-0.24. Meanwhile, this combination improved the soil nutrient status of N, P, and K, and the status of soil moisture and porosity, which demonstrated the increase of activity of soil organic matter and the improvement of soil fertility. So directly adding straw into soil without removing after harvest in autumn should be actively recommended, and the amount of corn straw added into soil should be 30 to 50 percent of the total production of corn straw.