Particularities of the Chemical Structure of Humic Acids from Soils under Shelterbelts of Different Age and Adjoining Cultivated Fields

摘要

One of the methods of controlling cycling of substances in agricultural landscape is to create biogeochemical barriers in the form of shelterbelts, decreasing the concentration of many chemical compounds migrating with ground water outflow from adjoining cultivated fields (2). In soils under shelterbelts compared to adjoining cultivated fields a higher content of organic matter (SOM) was observed, because the accumulation of soil organic matter under shelterbelts is suggested to be the main mechanism of long-term withdrawal of various chemical elements from cycling in the agroecosystems (2). Our previous researches showed the impact of the kind of the soil and the distance from the edge of the shelterbelt on the changes of urease activity, organic and inorganic forms of N, and the chemical structure of humic acids (HA). The transformation of N compounds in the soil under shelterbelts was found to be strongly connected with the humification process and the molecular structure of HA. For both mineral and mineral-organic soils, an increase in the distance from the edge of the shelterbelt was shown to be accompanied by a decrease in the degree of humification, or chemical maturity of the HA (3).