Changes in the structure of nitrogen-containing compounds of peat-, sapropel-, and brown coal-based organic fertilizers
¹Institute for Problems of Natural Resources Use and Ecology, National Academy of Sciencesof Belarus, Skarina str. 10, 220114 Minsk, Belarus; email: agrico@ns.ecology.ac.by
²Research Centre for Agricultural and Forest Environment of the Polish Academy of Sciences,ul. Bukowska 19, 60-809 Poznań; email: szajlech@man.poznan.pl.
Abstract:
The three-stage acidic hydrolysis method was used for the degradation of three organic fertilizers prepared on the basis of peat, sapropel and brown coal. This method of hydrolysis may simulate the processes that occur in the natural environment, influenced by chemical and biological factors with a high degree of reliability, by taking substances from fractions depending on stability of compounds in the investigated organic materials. The investigation of changes in the content of nitrogen in the studied fractions allows judging the character and the degree of transformation of nitrogen-containing compounds in kaustobioliths organic substances and prepared fertilizers. In these three organic fertilizers the content of readily (“easy”) hydrolysable nitrogen ranged from 49.1 to 58.4%, the content of hard-to- hydrolyse nitrogen ranged from 4.6 to 19.5%, in unhydrolysable rest, content ranged from 31.6 to 37%. The results showed a significant supply of nitrogen included in amino acid structures in soils. Amino acids represent a form of organic nitrogen, readily hydrolysable by chemicals and enzymes, available for plants and soil microorganisms. The highest supply was observed for the fertilizer prepared on the basis of brown coal. This fertilizer supplied 93.7 % more nitrogen than the reference soil. Two other fertilizers prepared on the basis of peat and sapropel supplied 64.1 % and 56.3 %, respectively more than reference soil. A relationship and good correlation were found between the contents of readily (“easy”) hydrolysable forms of nitrogen and the total amount of amino acids, and also between the contents of readily hydrolysable forms of nitrogen and concentrations of nitrogen in amino acid structures.
Key words:
amino acids, brown coal, nitrogen products degradation, organic fertilizers, peat, sapropel