Resumo

ALVAREZ-SOLIS, J. D.; DIAZ-PEREZ, E.; LEON-MARTINEZ, N. S.  e  GUILLEN-VELASQUEZ, J.. Organic amendments and soil metabolic activity in corn yield. Terra Latinoam [online]. 2010, vol.28, n.3, pp.239-245. ISSN 2395-8030.

The incorporation of sheep manure, corn stubble and leguminous cover crops are agricultural management practices used by some farmers to make fertilizers more efficient, or to reduce their use, in corn production systems. This study assessed the effect of these organic amendments on the soil metabolic activity and corn yield. In a field experiment established under rainfed conditions in Teopisca, Chiapas, Mexico, eight treatments were evaluated: conventional fertilization (120-60-00 of NPK) and fertilization reduced to 60% (72-36-00 of NPK) plus sheep manure (4.3 Mg ha^-1), both with and without the incorporation of corn stubble (5 Mg ha^-1) or botil and ibes bean (1 Mg ha^-1) cover crop. Data were analyzed under a design of randomized blocks which had four replications. The microbial biomass in rhizospheric soil samples at corn flowering was 20% higher with reduced fertilization complemented with manure, stubble and leguminous cover crop than with conventional fertilization without organic amendments. Organic C and microbial respiration did not vary significantly. The metabolic (qCO₂) and microbial (C microbial/C organic relation) quotients were influenced positively by the organic amendments, indicating greater efficiency in C utilization and an increase in the soil organic matter labil fraction. This was reflected in one ton increase in grain yield. The microbial biomass and microbial quotient showed a positive correlation with corn yield (r = 0.89 and 0.79). It was concluded that the incorporation of mixed manure, stubble and leguminous cover crop is an appropriate strategy for reducing inorganic fertilization, with positive effects on microbial biomass, organic matter and corn yield.

Palavras-chave : microbial biomass; organic matter; metabolic quotient.

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