Evolved carbon dioxide and nitrogen mineralization in a Dark-Red Latosol with different managements

Abstract

The objective of this work was to verify the influence of different types of straw (maize and lablab) and soil management on evolving CO₂ and N mineralization. A dystrophic clayey Dark-Red Latosol under Cerrado from the region of Sete Lagoas, MG, Brazil, was cultivated during five years with no-tillage, disc-plow and moldboard-plow. Soil samples (0-20 cm) were incubated at 25ºC during 55 days, with and without N fertilizer applied at the beginning and 25 days afterwards. As a general rule, the maize straw had higher rates of evolved CO₂ than the lablab (935 e 764 mg CO₂ g^-1 soil, respectively). The type of straw influenced the amount of CO₂ evolved more than the type of soil management did. Nitrogen addition increases the rate of CO₂ evolved only when applied at the beginning of the incubation period. The N availability and the duration of the immobilization are modified by the C/N ratio and by the type of soil management.