中国玉米生产-消费体系养分流动分析

Analysis on Nutrient Flow of Corn Production-Consumption System in China

采用物质流和养分流相结合的分析方法,沿玉米生产的肥料投入到玉米消费过程,研究氮、磷养分流动;以2004年为例,分析了中国玉米生产消费过程中氮、磷养分流动特点和资源的利用效率。2004年玉米生产投入化肥氮(N)549.6×104t、磷(P2O5)211.2×104t;共收获养分氮(N)342.9×104t、磷(P2O5)139.4×104t,其中75%的氮和68%的磷被利用,最终进入家庭的氮占22.3%,磷为15.0%;秸秆中氮的还田率只有47%,磷的较高,在80%左右,可见秸秆还田是归还土壤磷的有效措施。玉米生产要消耗大量的资源,2004年生产1t玉米养分,消耗的化肥氮、磷养分相当于煤5.2t、磷矿资源12.1t。因此,优化玉米整个生产与消费体系中养分的流动,对于提高养分资源利用效率和减少资源浪费具有重要作用。

The method that linked material flow with nutrient flow was adopted in this article in order to study nitrogen and phosphorus nutrient flows in the whole process from the fertilizer input to the consumption of corn.Nutrient flow model was firstly established in corn productionconsumption system.Taking the year 2004 for example,in which the characteristics of nitrogen and phosphorus in maize （including straw） and the efficiency of resources utilization were estimated.In 2004,5.496×10^6 tons of nitrogen （N） and 2.112×10^6 tons of phosphorus （P2O5） were applied into corn field in the form of chemical fertilizers;and 3.429×10^6 tons of nitrogen （N） and 1.394×10^6 tons of phosph were consumed.Corn was used for orns （P2O5） were harvested,in which 75%（N） and 68%（P2O5） making staple feed.The total amount of N and P2O5 that came into the families ,including directly by plant products and industrial products ,and indirectly by animal products,occupying 22.8% and 13.6% ,respectively.The ratio of returning straw to the field was quite low--phosphorus was about 80% ,higher than that of nitrogen ,which was 47%.So the returning straw to the field was regarded as an effective measure for phosphorus utilization. Nutrient flow began with the input of resource in the corn production-consumption system ,but the utilization efficiency of resources was very low.Lots of resources were consumed by corn production,while 1 ton of nutrients in corn was produced,nitrogen and phosphorus which were consumed in the form of fertilizer were equal to 5.2 tons of coal and 12.1 tons of phosphorite, respectively.Therefore ,optimizing nutrient flow in the entire corn production-consumption system was vital to the improvement of efficiency of nutrient resources and minimization environmental pollution.