NITROGEN SUPPLY POTENTIALITY OF UPLAND SOILS

Nitrogen supply potentiality of fluvo-aquic soils, yellow-cinamon soils, yellow-brown soils and red soils was studied. Results indicated that mineralization potential (No) of soils range from 60-340mgkg-1,and the mineralization rate constant(K) range from 0. 00556-0. 01280d-1.There was a good correlation between No, K, Nt and the capacity of soil nitrogen supply, which revealed that No, K and Nt could be used as parameters of soil nitrogen supply potentiality. These parameters were close to the corresponding soil composition properties, such as soil total N, OM, Organic N, easyly-oxidzed OM, C/N ratio. The results also showed that the clay mineral composition for most of the examined soils was mainly 2: 1 type minerals, and the amount of fixed ammonium was generally more than 100 mgKg-1. This fixed ammonium could also be released in part, therefore, it should be pay attention to in the study of soil nitrogen supply potentiality.