The evaluation of changes in soil humic substances composition and their nature in long-term experiments of Germany and Russia

摘要

The results of investigation of soil organic matter (SOM), its mobile and more strongly bound forms in long-term experiments on loamy soddy podzolic and grey soils of Russia and Loess-Chernozem of the Static Fertilization Experiment at Bad Lauchstadt in Germany are presented. The method of fractionation using successively 0.1 n sodium hydroxide (fraction 1), the mixture 0.1 m sodium pyrophosphate (fraction 2) and finally 0.02 n sodium hydroxide extraction on water bath (fraction 3) has been appliedfor isolation of humic substances differently bound with mineral part of soil. The results show that mineral and organic fertilizers differ in their effect on the composition of humic substances. The above mentioned properties of bound SOM fractions maypossibly serve as indicators of manuring intensity and accumulation of decomposable SOM in dark soils of temperate climatic conditions initially characterized by predominance of humic substances with high optical density. The results show the importanceof an optimum level of decomposable organic matter in soil and corresponding optimum fertilizer systems for every crop in rotation.