主要农作物秸秆养分资源现状及其肥料替代潜力分析——以安徽省为例

安徽省农作物秸秆资源丰富,充分利用秸秆养分资源对于农田养分投入的合理分配具有重要意义。评估全省主要农作物秸秆还田当季有效养分替代化肥潜力,可为安徽省减肥增效提供科学依据。本研究以安徽种植面积较大的主要农作物水稻、小麦、玉米、大豆、花生和油菜为研究对象,通过查阅安徽省统计数据和公开发表的文献资料,对2017年安徽省主要农作物秸秆数量、秸秆还田率以及还田当季养分利用率进行估算,明晰了全省化肥减施潜力。结果表明:2017年安徽省主要农作物秸秆资源量为4 699.9万t,秸秆资源分布上呈北部和中部较多、南部最少的特征。秸秆养分资源总量为124.8万t,N、P_2O_5和K_2O分别为38.1万t、11.4万t和75.3万t,分别占全省主要农作物养分需求的40.1%、32.1%和68.9%。理论上,秸秆全量还田,且养分充分利用的情况下,秸秆养分替代化肥潜力大。但秸秆养分N、P_2O_5和K_2O当季利用率分别为38.9%、52.3%和69.9%,实际秸秆N、P_2O_5和K_2O养分还田量仅占主要农作物养分需求的15.6%、16.8%和48.2%,分别占农田养分总投入量的8.6%、6.4%和41.4%。通过秸秆还田,全省可减施化肥63.3万t,减施比例为19.8%, N、P_2O_5和K_2O减施比例分别为11.4%、17.2%、40.7%。进一步提高秸秆还田率和当季养分释放率,是推进全省化肥减施增效的有利手段。

Current situation of the main crop straw nutrient resources and the substitute potential of crop straw for chemical fertilizer:A case study of Anhui Province

Anhui Province is rich in crop straw resources, it is important to fully utilize straw nutrient resources for the purpose of maintaining a nutrient balance in farmlands. For this cause, the potential of straw as a natural alternative to chemical fertilizers was evaluated in order to provide a scientific basis for the reduced use of chemical fertilizers in Anhui Province. In this study, we selected main crops such as rice, wheat, corn, soybean, peanut, and rape as study subjects in Anhui Province. We consulted the published literature and statistical data, and estimated the amount of straw, straw return rate, and nutrient utilization rate of main crops in Anhui Province in 2017. The results showed that the amount of straw estimated at 46.999 million tons in 2017. Furthermore, the distribution of straw resources was more in the northern and the middle regions of the province, and less in the southern regions. We also found that the total amount of straw nutrient resources was 1.248 million tons. The amounts of N, P₂O₅, and K₂O were 0.381, 0.114, and 0.753 million tons, respectively, and these accounted for 40.1%, 32.1%, and 68.9% of the main crop nutrient requirements of the entire province. Therefore, the potential of straw replacing chemical fertilizers is great in theory when all the straw is returned to the soil and the nutrients in the straw are fully utilized. However, the utilization rates of N, P₂O₅, and K₂O were only 38.9%, 52.3%, and 69.9%, respectively. The actual nutrients contents of N, P₂O₅, and K₂O of crop straws returned to the field accounted for only 15.6%, 16.8%, and 48.2%, respectively, of the nutrient demands of the main crops. Moreover, the actual amounts of N, P₂O₅, and K₂O returned to the field accounted for 8.6%, 6.4%, and 41.4% of the total input, respectively. By returning straw to the farmland, approximately 0.633 million tons of chemical fertilizer can be saved, representing 19.8% of the amount of chemical fertilizer that would have been used without the straw. It is also worth noting that the application reduction rates of N, P₂O₅, and K₂O were 11.4%, 17.2%, and 40.7%, respectively. Thus, the improvement in straw returning-to-field rate and release rate of nutrients in crop growth period point towards the benefits of promoting the reduced use of chemical fertilizers.