在现时栽培管理条件下,土壤肥力究竟起多大作用,是人们所关注的问题之一。为探求其实质,必须测知农作物一生中吸收土壤和肥料中营养物质的份额。晚近用同位素肥料示踪技术测试表明,在施足肥料的情况下,农作物吸收氮素的60～80%、磷素的65%以上是由土壤供给的,而来自肥料供应的营养物质仅占其吸收总量的三分之一左 Under the current cultivation and management conditions, soil fertility, how much effect, is one of the issues of concern. In order to explore its essence, it is necessary to measure the share of nutrients absorbed in soil and fertilizers throughout the crop’s lifetime. Recent tests using isotope fertilizer tracer have shown that in the application of sufficient fertilizers, crops absorb 60-80% of the nitrogen and more than 65% of the phosphorus is supplied by the soil, whereas the nutrients supplied by the fertilizer account for only One third of the total absorbed