THE EFFECT OF DIRECT APPLICATION OF PHOSPHATE ROCK ON INCREASING CROPYIELD AND IMPROVING PROPERTIES OF RED SOIL

Field experiments, designed to evaluate the effect of direct applicati on of phosphate rock, were carried out on red soil (Ultisol) uplands a t three different places. The results indicated: (1) for the first yea r's crop, the rapeseed yields with phosphate rock treatment and triple superphosphate treatment were almost identical when their rate of pho sphorus application was the same; (2) when the same level of phosphoru s fertilizer was applied, the residual effect of phosphate rock was be tter than that of triple superphosphate, and the residual effect of al l phosphorus fertilizers on winter crop yields increased with the incr ease of the amount of Phosphorus applied; (3) with the application of phosphate rock, the pH value, the amount of available phosphorus and e xchangeable Ca and Mg of soils went up, whereas the content of active Al in soils decreased. Therefore, the direct application of phosphate rock to red soil also has an important role in improving soil properti es.