Respiration and specific activity of soil microbial biomass under conventional and recuced tillage.


Pesquisa Agropecuaria Brasileira




The effects of two tillage systems, conventional (mold board plow) and reduced (harrow disk), on soil organic carbon and microbial biomass and activity were evaluated. Total organic carbon and microbial biomass were not affected by tillage, whereas carbon in the soil light fraction was higher in depth in plowed plots. Respiration os incubated samples and the specific ativity of the microbial biomass were also higher in subsurface soil under conventional tillage. This was associated (r=0,80) with carbon availability as indicated by the ratio light fraction-C/biomass-C. the CO2-C produced by the soil was originated from both a labile and a resistant pool. Conventional tillage determined an increase of the labile one. The CO2-C production in hte field was positively correlated with soil temperature and rainfall (r2=78-89). During summer, plowed plots generated 44% more CO2-C than umplowed ones. Plowing increased the available carbon pool size for microorganisms in depth but had no effect on CO2-C emission to the atmosphere on a year basis.


plow harrow disk organic carbon incubated samples organic matter arado grade de disco carbono organico amostras incubadas materia organica

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