Effects of Applying Ca Mg Phosphate on Nutrition and P Fraction in Yellow-red Soil of Young Chinese-fir Plantation

The effects of applying P fertilizer on nutrition and P fraction in yellow-red soil of young Chinese-fir plantation were studied in Jiangxi Province in 1991～1994. Fertilization increased the contents of organic matter,total N and P,available N and P,Fe-P and O-P in soil. Compared with the control,the contents of organic matter,total N and available N were increased by 43%,27% and 32% in treatment 5 (N100P100/ha) and 6 (N100P100K100 /ha),total P and available P were increased by 70% and 356% in treatment 5,respectively. The increased Fe-P (except for treatment 1) and O-P (except for treatment 3) ranged 2.5～13.9 mg/kg and 6～73 mg/kg,respectively. Ca-P in soil was reduced by 0.3～9.0 mg/kg in fertilized plots. There were different changes in organic P in various fertlized plots. Organic P was reduced by 87～128 mg/kg in treatment 2,5 and 6 while it was increased by 21～97 mg/kg in treatment 1,3 and 4. Compared with the control,there was no significance in the effects of fertilization on pH value and Al-P in soils.