Study on Difference of Potassium Fixation Capacity of Soils in Northern and Northwestern Regions of China
华北与西北地区典型土壤固钾能力差异研究

Experiments were conducted to study the difference of potassium fixation capacity of soils under 13 year application of K fertilizer and wheat straw return in the northwestern region and northern region of China. The results showed that continuous application of K fertilizer and wheat straw return could reduce fixation rate of added K significantly compared with NP treatment. With the increase of K concentration in the surrounding solution, K fixation capacity of soils increased but the percentage of the total K in the solution fixed by soils reduced. K fixation rate in subsoil layer (20 ~ 40 cm) was greater than that in the top layer soil (0 ~ 20 cm), and it was more obvious in the northern region. K fixation rate by soils under double cropping region was higher than original soil but contrary under sole cropping region. K fixation capacity increased from the northwestern region to the northern region.