Soil potassium reserves decide application rates of fertilizer potassium

Soil potassium reserves decide application rates of fertilizer potassium. In a potassium rich soil in the hilly region of Sichuan Basin, a long-term field experiment initiated in 1982 was conducted by the Soil and Fertilizer Institute, Sichuan Academy of Agricultural Sciences to test soil K supply power and duration in intensive, irrigated rice -wheat systems with crop residue removal from the field. Results showed that soil native K can supply healthy crop growth and crop yields equivalent to the treatment of NPK for up to 15 years. The minus K treatment achieved rice yields 2.8%-9.9% lower and wheat yields 1.3%-12.4% lower than the NPK treatment in the following 16 years. While in another long-term field experiment conducted in a potassium deficient soil in intensive, irrigated rice -wheat systems with crop residue removal from the field located in Chengdu Plain of Sichuan province , omission of K in the fertilizer program for one season reduced wheat yield by 10.3% and rice yield by 8.7% and continued omission of K reduced wheat yield by 49% and rice yield by over 15% compared to the NPK treatment in the second year.