Some biochemical aspects of Fragi-Stagnic Albeluvisols’ organic matter

L. Szajdak¹, P. Kuldkepp², E. Leedu², T. Teesalu², A. Toomsoo² and R. Kõlli2*

¹Research Centre for Agricultural and Forest Environment, Polish Academy of Sciences, ul. Bukowska 19, 60-809 Poznań, Poland; e-mail: szajlech@man.poznan.pl
²Institute of Agricultural and Environmental Sciences, Estonian Agricultural University, Kreutzwaldi 64, 54014 Tartu, Estonia; e-mail: raimo@eau.ee
*Author for correspondence

Abstract:

The concentrations of N-NH₄⁺, N-NO₃^–, N_total, total (TOC) and water extractable (DOC) organic carbon, P, K, Ca, Mg, S, the activity of nitrate reductase, the activity of urease activity as well as indole-3-acetic acid (IAA) were investigated in Fragi-Stagnic Albeluvisols’ organic matter under different organic and mineral fertiliser regimes from a long-term soil formation of a field experiment with three-field crop rotation (potato – spring wheat – spring barley) at Eerika near Tartu, Estonia, and also in the forest of Tiksoja. The concentrations of N_total, IAA, the activity of urease and also C/N ratios were generally highest in the forest soil of Tiksoja.
Consequently, characteristics, distributions and conversions in organic matter were found in the proportions of chemical and biochemical factors, particularly after mineral and organic fertilisers. The following kinds of fertilisers increased the activity of urease in the order: WOM/N-120 < FYM/N-120 < RS/N-120 (accordingly, WOM – without organic manure, FYM – farmyard manure, RS – recultivation substance), and increased the activity of nitrate reductase: WOM/N-120 > RS/N-120 > FYM/N-120. The highest increase of IAA was determined in the soil fertilised with RS/N-120.
The experiment was characterised by the highest activity of urease, and the highest increase of IAA and also TOC in soils fertilised with RS/N-120. The various fertiliser regimes were different both for their biochemical factors as well as the crop yields. WOM/N-120 as a mineral fertiliser and RS/N-120 as an organic one revealed the highest crop yield of potato, spring wheat, and spring barley.

Key words:

Albeluvisols, auxine, crop yields, long-term field experiment, organic and mineral fertilisation, organic matter, urease and nitrate reductase