EVALUATION OF SUBSTRATES MINERALIZATION BY C-CO2 FLUX UNDER NITROGEN FERTILIZATION

Abstract

The objective was to evaluate the mineralization of two mixtures of substrates with different nitrogen content, moisture, compost and mineral mixture based on zeolite and dolomite. The measured parameters were pH (extract 1:2), electrical conductivity (extract 1:5) by conductimeter; content of organic matter by ignition; organic carbon based on the results of organic matter using the Douglas factor= 0.5; and nitrogen per micro Kjeldahl. The flow of CO2 was measured with the IRGA gas analyzer. For both moisture content, the compost-free substrates had a higher C/N ratio. Compost substrates, because of their high mineralization, were appropriate with advantages to the supply of nitrogen. Substrates with compost and 15% moisture released higher CO2 by presenting more easily degradable compounds. Mineralization rates on substrates were higher with 15% humidity due to increased porous space occupied by gases, in addition, the supply of 50% of nitrogen had a low immobilization due to the lower organic matter content and the 40 cm3 L-1 mineral mixture content changed the dilution of carbon to be metabolized by microorganisms. The rate of mineralization was affected by the use of minerals, the quality and the subtrate origin