Dados do Trabalho

Título

BIOLOGICAL INDICATORS OF SOIL HEALTH IN DESERTIFIED DRYLANDS IN BRAZIL

Resumo

Drylands comprise ~ 41 % of the Earth's land surface, where 10 - 20 % of these areas are degraded in Brazil. Overgrazing is pointed out as one of the causes of the advance of desertification in the region. Despite this, the effects of desertification in the Brazilian drylands on Soil Health (SH) are still poorly understood. This study aimed to use the Soil Management Assessment Framework (SMAF) platform to evaluate the impact of management practices on the biological indicators of healthy soils inserted in the Desertification Nucleus of Irauçuba/CE, in 3 sites with 2 different managements each: i) Grazing-exclusion for 21 years (RE), ii) areas in the process of desertification by overgrazing (DE), and iii) areas of Caatinga native (NV) as a control treatment. Soil samples were collected in the 0 - 10 cm layer during the rainy and dry seasons, totaling 54 samples (3 sites x 3 (2 managements + 1 control treatment) x 3 blocks x 2 seasons). The results show that the NV and RE areas had the highest soil organic carbon contents in both sampling periods, with a significant increase in the dry. However, DE showed the lowest values in both rainy (6.69 g dm-3) and dry (8.61 g dm-3). Microbial biomass carbon (MBC) contents were highest in the dry in all managements, but RE showed the highest content (285.21 mg kg-1). On the other hand, MBC contents in DE were lower in both periods (6.69 mg kg-1 in rainy and 8.61 mg kg-1 in dry). β-glucosidase activity was higher in RE and NV than in DE in both periods. Possibly, the increase in SH is driven by the biological balance that occurs through the increase in biological indicators. The grazing exclusion proved effective in the recovery of SH, reaching levels similar to those of native vegetation. These results highlight the need to conserve and restore desertified areas, aiming to preserve soil fertility and agricultural sustainability in the Brazilian drylands.

Palavras-chave

Caatinga, SMAF, grazing exclusion, overgrazing, carbon.

Instituição financiadora

FEALQ, FAPESP, CAPES, SHELL

Agradecimentos

Sohma research group, ESALQ-USP, FEALQ, FAPESP, CAPES, SHELL