SOME CHEMICAL PROPERTIES OF SOIL ORGANIC MATTER AND OF SESQUIOXIDES ASSOCIATED WITH AGGREGATION IN SOILS

Abstract

Proximate chemical analyses of the organic matter and related data were obtained for a well-aggregated and a poorly aggregated fraction of 8 Kansas soils. These represent 4 "slick spots" and 4 differently treated plots of the fertility series of the Kansas Agric. Expt. Station Agronomy Farm. Cultivation and various soil treatments changed the chemical composition of the organic matter of some of the fractions. The C and N content was higher in the well-aggregated than in the poorly aggregated fraction. The alcohol-soluble portion of the organic matter was low in the well-aggregated fraction in all cases. The ether-soluble material was also low in the well-aggregated fraction of the "slick spots" but in the fertility plots the reverse was true. As a result of certain soil treatments the lignin content of both of the differently aggregated fractions of the soil fertility samples was increased but their protein content was decreased. In general, the nitrogenous material in the poorly aggregated fraction was more completely extracted by hydrolysis with weak HCl than was that found in the well-aggregated fraction; this was not true for the H2SO4 treatment. Both acid hydrolyzates of the poorly aggregated fractions tend to contain a large proportion of their N in the amide form. Larger amts. of sesquioxides were removed by the acid extractions from the well-aggregated fractions than from the poorly aggregated fractions. In the "slick spots" this difference averaged more than 3:1.