No abstract

The spatial variability of microbial biomass C and three humification indexes (the degree of humification, DH; the index of humification, HI; and the humification rate, HR) were investigated in order to evaluate their usefulness as indicators of the response of soil organic matter to altered soil environments. The investigation was carried out by examining the topsoil layer of an experimental field characterized by the presence of four phases of one soil series and, except for the addition of cattle manure in part of the field, by fairly uniform agricultural practices. A rectangular area of 350 by 800 m was sampled on a square grid scheme coupled with nesting. The experimental objective was to determine if the investigated properties were influenced by changes in soil type and by the addition of cattle manure. All properties measured showed spatial dependence at the sampling distances adopted. Two groups of properties were identified based on their degree of spatial variability: microbial biomass C, DH, and HI exhibited short‐range variability, whereas HR varied across longer distances. Microbial biomass C and HR showed a spatial pattern related to soil amendment and soil types, respectively. Therefore, these variables provided complementary information about the condition of soil organic matter in the study area.