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本试验首先把７种采自不同省份的耕作土壤进行物理分级，然后测定了土壤Ｃ、Ｎ、Ｐ、Ｋ在不同粒级中的分布，同时还进行了不同粒级中Ｎ的有效性研究。结果表明：在不同粒级中Ｃ、Ｎ含量和分布均随土壤颗粒的加粗而逐渐下降，而Ｃ／Ｎ比则与此相反。在＜２μｍ粒级中Ｎ的有效性最高，随着土壤颗粒粒径的加粗有效性逐渐降低。在酸性土壤中Ｐ主要分布在较细的粒级中，而在石灰性土壤中则主要分布在较粗粒级中。土壤交换”性钾和缓效性钾主要分布在＜５０μｍ粒级中，表明该组分中Ｋ是作物吸收Ｋ的主要来源。
In this study, seven cultivated soils from different provinces were physically graded, and then the distribution of soil C, N, P and K in different grain fractions was determined. At the same time, the validity of N in different grain fractions was also studied. The results showed that the content and distribution of C and N in different grain fractions decreased with the increase of soil particle size, while the C / N ratio was the opposite. In the <2μm grain size, N is the most effective, and as the soil particle size is bolded, its effectiveness decreases. In acidic soil, P mainly distributes in finer grain size, while in calcareous soil it mainly distributes in coarser grain grade. Soil exchange "Potassium and slow-acting potassium are mainly distributed in the grain size <50μm, indicating that K is the main source of K absorbed by the crop.