Dynamic of the active fraction of organic matter in some meadow soils

Authors : Mahtali SBİH, Antoine KARAM, Adrien N’DAYEGAMİYE, Zoubeir BENSİD, Amar BOUKABOUB

Pages : 22-27

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Publication Date : 2012-03-01

Article Type : Research Paper

Abstract :The microbial biomass insert ignore into journalissuearticles values(MB); and light fraction insert ignore into journalissuearticles values(LF); of organic matter are often considered as active fraction of organic matter insert ignore into journalissuearticles values(AFOM); and as indices of soil fertility and microbial activity. This study was performed in order to assess the turnover of AFOM using long-term incubation insert ignore into journalissuearticles values(56 weeks); at25 °Cin 34 meadow soils with different physical and chemical properties such as soil texture, organic C and total N. The MB and LF were determined at 8 and 5 times during the incubation period using fumigation-extraction technique for MB and densimetric method for LF. The amount of MB-C and MB-N mineralized increased with time of incubation. At the beginning of incubation, the C and N content of soil MB represented respectively 0.76 to 3.7% of total organic C and 1.94 to 10.7% of total N. The C and N content of LF represented respectively 2.9 to 25.6% of total organic C and 1.7 to 17.5% of total N. At the end of incubation, the losses of MB-C and MB-N from soils reached respectively 71 and 82% of the initial amounts. The MB and LF dynamic were well described by a two-component first-order rate model. The amount of N in the labile MB and LF pools represented respectively 54% of total MB-N and 61% of total LF-N. The more stable MB and LF pools had higher half-life than labile pools. The results obtained indicated that the stable LF would be the precursor of soil humic compounds.
Keywords : microbial biomass, light fraction, carbon and N dynamic