Back R. L. L. Berbara1, L. P. Canellas2 and F. Gurundi3
Department of Soil Science, UFRRJ, Seropedia, RJ, Brazil1,
UENF-CCTA-Solos, Campos dos Goytacazes, RJ, Brazil2 and
Universidad Nacional Agraria de La Habana, Depto. Quimica. San Jose de
las Lajas, La Habana, Cuba3
Full Paper (PDF File: 56KB)
Abstract
Organic matter is a indicator of soil quality. The study of its quantity, fractions and stability is an important factor in the determination on how sustainable is the soil management. One of the techniques used to improve crop quality is the use of the biofertilizers such as EM-4. As it stimulates the microorganisms activity in soil, it may also modify the rate of CO2 evolution and affect the distribution of organic C in the humidified fractions. The objective of the present study was to determine the effects of the use of EM-4 on the stable organic C fraction. To this end, experiments were performed to study the organic fractions contained in the activated EM-4 extract; to determine the rates of CO2 evolution in soil samples with and without the addition of plant residues and EM-4. Quantitative distribution of humidified SOM and the spectroscopic characteristics of FA, HA and humin was also studied. An increase in evolved CO2 was observed in all treatments that involved EM-4. It also interfered with the formation of humic substances, incuding structures with a greater conjugation. This characteristic provided greater chemical stability and resistance to degradation by the subsequent action of microorganisms. This confirms the initial hypothesis that the use of EM-4 stimulated microbial activity and consequently the ability of the soil to degrade more rapidly the plant residues.