EFFECT OF DIFFERENT HUMUS CONTENTS ON N-M INERALIZATION AND C-MINERALIZATION AND THE IMPACT OF FERTILIZER APPLICATION

A continuous trial was made on Albic Luvisol/Leptic Podsol/Orthic Luvi sol to determine the effect of different humus contents on N and C min eralization and the impact of fertilizer application. In soils with lo w percentages of easily mineralizable organic matter, N mineralization rate amounted to 1.8% as was found from the N extract rates. Higher o rganic matter contents led to an increase in N mineralization and to a n annual C mineralization rate of 0.75 t/ha. Fertilizer application (f armyard manure and mineral fertilizer) did not compensate within short times the differences in organic matter supply of the soils in terms of yields and N extract rates.