Abstract:

【Objective】 Experiments were conducted to study the difference of potassium fixation capacity. 【Method】Fixed-site researches on cultivated layer of soil under long-term application of K fertilizer and wheat straw to soil for 13 continuous years in selected regions of north China were carried out. After 13 years, soil samples of different treatments collected from each fixed-site were treated with different concentrations of KCl solution to study K fixation capacity of typical soil in northern China.【Result】 The results showed that continuous application of K fertilizer and wheat straw could reduce the fixation rate of added K significantly, and when the concentration of K increased from 1 000 mg•L-1 to 4 000 mg•L-1 in the soil solution, K fixation capacity of soils increased at the same time. In the same region, K fixation rate of soils in double cropping regime was higher than that in single cropping regime. K fixation capacity of soil showed a clear increasing trend of distribution from the west to the east. When the K concentration in the surrounding solution was 1 000 mg•L-1, the average K fixation rates of soils in NP treatment were 348.5, 442.9, and 468.5 mg•kg-1 in Northwest, North China and Northeast China, respectively. 【Conclusion】 Difference in potassium fixation rate between soils with depletion of K successively and soils supplied with K successively is an important character for judging the condition of soil potassium.

Key words: long-term application of K fertilizer, wheat straw to soil, selected soils from northern China, K fixation capacity