Abstract: Based on K fertilizer’s application and straw-returning to soil of Hebei chao soil and Shanxi brown soil in northern China for continuous 13 yeas, effect of K fertilizer’s application and straw-returning to soil on crop yield and status of soil potassium in plough layer under different planting systems was studied. Results showed that K fertilizer and straw could improve yield of wheat and maize, and treatments showed: NPK+St>NPK>NP+St>NP, and treatment of K fertilizer’s application made a notable difference to NP, and efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. By contrast with Shanxi, soil potassium wastage of rotation system in Hebei was more serious, only treatment of NPK+St showed a surplus in soil potassium. K fertilizer and straw could improve content of water-soluble K, non-specifically adsorbed K, non-exchangeable K, mineral K and total K in contrast to NP, however reduce proportion of mineral K and improve others’ in two anchors, but content and proportion of specifically adsorbed K had nothing to do with K fertilizer and straw. Effect of K fertilizer’s application to soil directly was wholly excelled to straw. In contrast to orientation’s beginning, time-variation character of soil potassium’s content and proportion showed a difference between two agrotypes, further more content of mineral K and total K behaved a decrease accordantly in two anchors’ soil.

Key words: different planting systems, long-term K fertilizer’s application, straw-returning to soil, crop yield, soil potassium