Effect of long-term located fertilization on the quantity-intensity characteristics of potassium in sheltered vegetable field soil.

Effects of 18 long-term located fertilizations on the quantity-intensity characteristics of potassium in sheltered vegetable field soil were investigated. The results showed that there were great differentiations between the quantity factor(-?K0)、intensity factor (AReK) and potential buffering capacity of K+ (PBCK) in different treatments, and the changes of basic physical-chemical properties contributed to this. When the contents of soil CEC, fast-available potassium, clay and organic matter were increased, the value of -?K0 and AReK increased but the value of PBCK decreased. The main reasons for changes in quantity-intensity characteristics of each treatment were different. The treatments using organic fertilizer presented a high value of -?K0, AReK but a low value of PBCK,primarily owing to the higher content CEC and fast-available potassium; the treatments using potassium also presented a high value of -?K0、AReK and a low value of PBCK, while the main reason may be the higher content of fast-available potassium; the treatments using great amount of urea produced a high value of AReK only but a low value of PBCK,-?K0,properly owing to the higher amount of NH4+.