Long-Term Soil Ecosystem Studies

Transformation of Carbon (C) and Nitrogen (N) soil levels occurs very slowly and long-term experiments provide the opportunity to compare these slow changes in the soil C stocks and the soil organic matters (SOM) quality parameters under specific climatic conditions and management systems and estimate the direct as well as indirect influence of different factors. At present the Geographical Network of Field Experiments in Russia includes more than 300 experiments, about 40 of them lasting more than 40 years. In the transitional period since 1991 some in field experiments have had changes in the management practices forced on them more than 20 – 30 years after their foundation. Such experiments represent the most interesting sites for study of soil sustainability following the introduction of low-input management systems. Soil organic matter sustainability can be low in systems with only mineral fertilization at high rates. Presumably, mineral fertilizers with sustainable effect on the loss of Ca-forms of humic substances contribute significantly to the formation of the labile SOM forms. Soil organic matter from the plots that have received combined farmyard of manure (FYM) and mineral fertilization is considered to be the most resilient and sustainable. The simulation results of SOM dynamics of Russian long-term field experiments with the static model allow calculating quantitative parameters for controlled factors, which can be used to select an optimal agricultural strategy.