我国秸秆资源养分还田利用潜力及技术分析

Study on potential of straw resource nutrient return to field and application technology in China

我国秸秆资源量丰富,且含有大量的养分,将这些养分还田利用,不但可以减少化肥的投入,还可以避免资源浪费,保护生态环境。通过资料收集和数据统计,对我国的秸秆资源状况、空间分布、养分利用潜力及养分还田技术进行了分析。结果显示:2017年我国秸秆资源量约为8.55亿t,秸秆全量还田养分输入量分别为758.66万t(N)、238.84万t(P2O5)、1 316.36万t(K2O),分别可替代当年约34.15%的氮肥、29.95%的磷肥、212.40%的钾肥。根据当年秸秆综合利用情况和养分还田率,还田的养分可替代约19.38%的氮肥、23.28%的磷肥、166.81%的钾肥。相比秸秆全量还田,实际还田养分的可替代化肥率还有较大的提升潜力。此外,秸秆中还含有34 238.94万t的有机碳(未包括棉花秸秆),按30%的转化率计算,将有超过10 000万t的有机碳进入土壤。选取我国秸秆养分量最高的3个区域,对其秸秆养分还田技术进行分析,并提出在东北地区应以秸秆粉碎翻耕或旋耕还田为主,定期进行深翻作业;黄淮海地区应以小麦秸秆粉碎后覆盖以及玉米秸秆粉碎后旋耕或深耕还田为主,增加耕翻深度,及时将秸秆还田,定期进行深翻或深松作业;长江中下游地区应以秸秆粉碎旋耕混埋还田技术为主,严格控制机械切碎长度和旋耕深度。此外,在东北和黄淮海地区应将过腹还田与堆沤还田作为机械化直接还田的重要补充,在长江中下游地区应推广秸秆腐熟还田技术。

Straw resources are huge and contain a lot of nutrients in China.Returning these nutrients back to the farmland will not only reduce the input of fertilizers,but also avoid waste of resources and protect the ecological environment.Through data collection and statistics,the status of straw resources,spatial distribution,potential of nutrient utilization and straw returning technology counter measures were analyzed.The results showed that in 2017,the amount of straw resources in China are about 855 million tons,and the theoretical nutrient content is about:7.586 6 million t(N),2.388 4 million t(P2O5)and 13.163 6 million t(K2O),which can replace 34.15% nitrogen fertilizer,29.95% phosphate fertilizer and 212.40% potash fertilizer of the year.According to the actual straw utilization and nutrient returning rate in the current year,straw resources can replace about 19.38% of nitrogen fertilizer,23.28% of phosphate fertilizer and 166.81% of potash fertilizer.Therefore,straw nutrient returning to the field not only has a huge potential for replacing fertilizer,but also has a large potential for improvement.In addition,straw also contains 342.389 4 million t of organic carbon resources(not including cotton stalks),if calculated at 30% conversion rate,there will be more than 100 million t of straw organic carbon returning to the soil.Three regions with the highest straw nutrient content in China were selected,and the straw nutrient returning technology was analyzed.It was suggested that ploughing or rotary tillage should be used in the northeast region,and deep tillage should be carried out regularly.In huang-huai-hai area,wheat straw pulverized and covered returning,corn stalks pulverized and rotary tillage returning should be used as the main method,and be accompanied by increasing the depth of ploughing,returning the straw to the field in time,and carrying out deep turning or deep loosening regularly.In the middle and lower area of the Yangtze River,the technology of straw pulverization,rotary tillage and mixed burial should be the main method,and the mechanical cutting and the depth of rotary tillage should be strictly controlled.Secondly,in the northeast and huang-huai-hai area,the straw compost returning to field and livestock manure returning after feeding straw should be used as important supplement for mechanized direct returning.In the middle and lower area of the Yangtze River,the technology of straw maturity returning should be promoted.