Department of Plant Sciences

From 2001 to 2008 a total of 16 field experiments were conducted in Jilin province, the so called “maize belt” of China, to study the rate of potassium fertilizer required for high yield maize production and maximum economic return under different soil available K levels. Results indicated that application of K2O at rates from 53.4 kg/ha to 155.4 kg/ha at different field sites with different soil available K levels produced maximum maize yield of 6203 kg/ha to 13668 kg/ha in the region. For maximum economic return the proper rate of K2O ranged from 37.6 kg/ha to 115.5 kg/ha, resulting in maximum economic yield from 6187 kg/ha to 13660 kg/ha. The net benefit ranged from 264 Yuan/ha (38.8 US$/ha) to 1977 Yuan/ha (290.7US$/ha), and the value and cost ratio (VCR) ranged from 1.5 to 8.0. As expected, the result indicate that soils with relatively low soil available K level received a high K2O recommended rate, while soils with relatively high soil available K level received a lower recommended rate of K2O. The use of soil testing provided a better distribution of limited fertilizer K resources and supported an overall improved net benefit to farmers.