Changes in attributes of soils subjected to fallow in desertification hotspot

Resumo

Soils in semi-arid regions have been degraded by overgrazing, which reduces the production capacity and, in
certain situations, leads to desertification. An alternative to recover degraded areas is the fallow period, which works through
the resilience of the soil itself, increasing the supply of organic matter and improving soil physical properties. Thus, the
objective of this study was to test the hypothesis that 14-year grazing exclusion improves soil physical and chemical attributes
in degraded areas under desertification. The study was conducted in Irauçuba, Ceará State, Brazil. The experimental design was
completely randomized, in a 4 x 2 factorial scheme corresponding to four areas and two managements (overgrazing and fallow),
with four replicates, plus an area with native vegetation (reference), with characteristics of secondary vegetation. Fallow led
to improvements in soil physical and chemical attributes after 14 years; however, in comparison to the study conducted in the
same area with a 7-year fallow period, there were few alterations. Organic carbon content was higher in fallow areas than in
overgrazing areas, and the fraction in highest proportion was the mineral-associated organic carbon.