Simulated tests were conducted to study the leaching characters of phosphate fertilizer applied in the latosol derived from
Gneiss in laboratory. The results were indicated as follows. The
accumulative amount of PO43- in the leachate increased with the increase of phosphate
fertilizer applied, but not just in a linear increasing relation. The accumulative leaching of PO43- had a ″change point″ when the phosphate fertilizer applied was between 106.1 kg/hm2 and 70.7 kg/hm2. The motion of phosphorus was very weak in the latosol. The activated phosphorus could not penetrate the 12 cm soil layer when the phosphate fertilizer was applied in the latosol under 141.5 kg/hm2. At low irrigation quantity, the accumulative amount of PO43- was nearly in a linear relation to the added water, whereas at high irrigation quantity, there was no significant difference between the accumulative amount of PO43- and the added water. With the equal total irrigation quantity, small amount of irrigation in several times was more effective in promoting the movement of phosphorus than large amount in a single time.