摘要： 在我国不同地区的20种土壤类型农田土壤上进行的大量田间试验和土壤测试证明，我国农田土壤氮素肥力较低，无氮区作物相对产量平均为69。0%，其中氮素肥力“低”的占65%，“中”的占35%，没有氮素肥力“高”的土壤类型。土壤磷素肥力中等，无磷区作物相对产量平均为86。4%。其中磷素肥力“高” 的占32%，“中”的占59%，“低” 的占9%。土壤钾素肥力中上，无钾区作物相对产量平均为93.7%，其中钾素肥力“高”的占41%。“中”中的占56%，“低”的占3%。根据土壤测试和作物相对产量，对全国20种类型农田土壤拟定了土壤养份丰缺指标。

关键词: 土壤肥力, 作物相对产量

Abstract: A large number of soil fertility analysis and field trials were carried out in different regions of China.Results confirmed that soil nitrogen fertility in 20 tested soil types is low.The crop relative yield in N treatment is 69% in average,of which 65% accounts for"low nitrogen level",35% for"medium level",and none is"high"in nitrogen.Soil phosphorus fertility in these soils medium.The crop relative yield in-P treatment is 86.4% in average,of which 32% accounts for"high level"59% for"medium level",and 9% is"low"Soil potassium ferility in these soils is from medium to high.The crop relative yield in-K treatment 93.7% in average of which 41% accounts for"high level",56% for"medium level",and only 3% is"low".Soil fertility index for the 20 soil types have been worked out in accordance with soil test results and crop relative yields.

Key words: Soil fertility Index, Crop relative yield