Potassium Fixation and Release Characteristics of Several Normal and K-Exhausted Soils in the Middle and Lower Reaches of the Yangtse River, China

Potassium (K) fixation and release in soil are important factors affecting K availability to plants and the utilization efficiency of K fertilizer. Three typical soils (red soil, yellow cinnamon soil, and alluvial soil) were collected from the middle and lower reaches of Yangtse River, China, to study the K-fixation and K-release characteristics of the normal and K-exhausted soil. Results showed that K fixation of added K in K-exhausted soils were significantly (P yellow cinnamon soil > alluvial soil, but the cumulative amount of K released from the three soils during successive extractions with 1.0 mol L−1 nitric acid (HNO3) was in the opposite order. The cumulative amounts of K released with 1.0 mol L−1 ammonium acetate (NH4OAc) and 1...