Biological indices of soil organic matter in long term fertilization experiment

Abstract

Dynamics of labile fractions of soil organic matter under 36-years of application of mineral and organic fertilizer in Chernozem (Mollisol) in Ukraine were studied. "Light" fractions of SOM between various mineral and organic fertilization treatments were studied. Amount of total organic C increased in manured treatments; while amount of total N didn't change under any of the treatments. Labile N was correlated to soil mineral N, MBC and MBN, LFN and LFC, while labile C correlated to the total organic C, LFC and LFN. The pattern of mineralization and accumulation of SOM suggested that OC dynamics more related to long-term substrate addition, while N dynamics better reflects short-term substrate addition. Application of mineral fertilizer alone accelerated mineralization of SOM, especially of "light" fraction, while partial or complete replacement of inorganic by organic fertilizers has a significant impact on soil microbial community and soil capability to supply plants with nutrients for longer period.