Changes in the structure of nitrogen-containing compounds of peat-, sapropel-, and brown coal-based organic fertilizers

G. Sokolov¹ L. Szajdak² and I. Simakina¹

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

Impact of the farming systems on the content of biologically active substances and the forms of nitrogen in the soils

T. Meysner¹, L. Szajdak¹ and J. Kuś²

¹Research Center for Agricultural and Forest Environment, Polish Academy of Sciences,Bukowska 19, 60-809 Poznań, Poland; e-mail: szajlech@man.poznan.pl
²Institute of Soil Science and Plant Cultivation, Czartoryskich 8, 24-100 Puławy, Poland;e-mail: jankus@iung.pulawy.pl

Abstract:

Investigations were carried out in 2000 and 2001 to assess the impact of four farming systems on the content of biologically active substances and different forms of nitrogen in the soils. The transformation of bound amino acids and the total amount of free phenolic acids, urease activity as well as the total nitrogen, concentration of ammonium, nitrate, organic carbon, and humus in the soils were related to the choice of the farming systems. The highest concentration of bound amino acids, lysine and β–alanine, the total nitrogen, organic carbon, and humus in soils was found in ecological and conventional systems. It was confirmed that the increase of free phenolic acids in the soils of continuous cropping of winter wheat was followed by the decrease of the yearly mean concentrations of urease activity, the total amount of bound amino acids, the total nitrogen and grain yields, weight of 1000 grains, and number of ears m-2. The conventional system affects the increase of the yearly mean concentrations of the total amount of bound amino acids, the ammonium ions, and the grain yield, weight of 1000 grains, number of ears m-2 and the decrease of the total amount of free phenolic acids in the soils.

Key words: