A Multidisciplinary Approach to Assessing Changes in Soil Quality of Diverse Farming Systems

Abstract

Soil quality methodology can be used to characterize and define management factors contributing to soil degradation. A minimum data set of indicators, measured collectively, can elucidate changes within the soil ecosystem. Physical (bulk density, infiltration rate), chemical (pH, inorganic N, organic N and C), and biological (soil respiration, fluorescent Pseudomonas bacteria and entomopathogenic nematode populations) indicators were measured over two years in a best management practice (BMP) conventional tillage (CT) and no-tillage (NT), organic, and successional (fallow) systems. At this early stage in the systems development, statistical differences between systems are few, but developing trends are evident. Preliminary results show higher microbial activity in undisturbed systems and where crop residue is left on the soil surface. Soil respiration values were higher in the BMP (NT) and successional systems throughout the growing seasons. Whereas Db was higher in the BMP (NT) and successional system, values were not root restrictive. Measurements of fluorescent Pseudomonas and entomopathogenic nematodes serve to act as a survey of endemic populations at this early stage in a long-term experiment. Treatment effects on infiltration time were masked by differences in soil type. This baseline information will be used to evaluate the amount, direction and speed of change in the systems over the long term and to assess the value of this set of indicators in relatation to soil quality and crop productivity.