STUDY OF MAIZE’S P AND K FERTILIZATION ON ALFISOLS (Typic rhodustalfs) WITH ARTIFICIAL SOIL NUTRIENT CLASS

This research was conducted on dry land in Gowa District, South Sulawesi, using a single location approach. Soil types in Gowa District are classified as Alfisols. The aims of this research are to determine the critical values of P and K for maize; and also, to know P and K fertilization of maize on various extraction and nutrient classes of artificial soil. Treatments were arranged as a split-plot in randomized complete block design with three replications. The main plot was artificial soil nutrient classes (very low, low, moderate, high, and very high of P and K) and subplot were fertilization of P and K. The results indicated that the critical values of P and K for maize on Alfisols (Typic Rhodustalfs) are 0.32 ppm P, 85 mg P100 g-1, 0.42 ppm P, and 1.04 ppm P for each Mechlish, HCl 25%, Bray-1, and Bray-2 extractions, respectively, and 0.37 me K 100 g-1, 0.55 me K 100 g-1, 178 ppm P, 213 ppm P for each NH4OAc pH 4.8, NH4OAc pH 7, Bray-1, and Olsen extractions, respectively. P and K fertilization, which gives the highest of maize yield, is obtained of 40 kg P, 80 kg P and 160 kg P ha-1 for the high class, moderate class, and low class of P. While for K fertilization, the highest yield was 20–40 kg K, 40–80 kg K and 80–160 kg K ha-1for the high, moderate and low class of K, respectively.