A incorporação de calcário em sistema plantio direto consolidado reduz o estoque de carbono em macroagregados do solo

Abstract

Carbon stocks in soil macroaggregates are related to the rate of soilCsequestration in no-tillage system. This study aimed to evaluate carbon stocks in macroaggregates (12.5 to 19.0mm) as a function of the occasional tillage and/or liming of a Hapludox loamy clayey under no-tillage for 17 years in Pato Branco, Paraná southwest, Brazil. Starting from October 2009, it was evaluated an experiment with split-split plots, with plots as sampling dates after 6, 12 and 20 months of the occasional tillage and/or liming; the subplots as soil management, with and without occasional soil tillage with plowing and disking; and as sub-subplots, liming levels, with and without limestone to raise the base saturation index to 70%. From 6 to 12 months, the limestone application on surface or incorporated increased C stocks of macroaggregates in the 0.10-0.20m layer. After 20 months, the incorporation of limestone in soil reduced C stocks in macroaggregates only in the 0-0.10m layer. Thus, the surface liming is essential for the maintenance and enhancement of C stocks in macroaggregates of no-tillage system, keeping it consolidated.