Abstract
Soil degradation imposes significant environmental and economic impacts
on the pastures of drylands worldwide, making livestock grazing systems
often unsustainable under the present climate conditions. In this study,
we aimed to compare the attributes of the soil of different grazing
areas (pastures) using sensitive indicators of changes in the management
of these areas, such as the physical-hydric properties and the
CO2 efflux (ECO2) from the soil. The
study was carried out in three areas of exclosure grazing, understood by
three land uses: a pasture of sabi grass (LU1), a silvopastoral system
with sabi grass and tree legume (LU2), and an area with sabi grass and a
herbaceous native legume (LU3). The measurements were undertaken over
nine months and then grouped into three seasons (dry, transition, and
rainy). The ECO2 and the ten indicators of soil
physical-hydric quality were measured: macroporosity, aeration capacity,
plant-available water capacity (PAWC), relative field capacity (RFC),
characteristic pore radius, quantity of hydraulically active pores,
sorptivity, saturated hydraulic conductivity, soil density, and soil
resistance to penetration. The soils in the LU1 and LU3 areas showed
limited plant available water capacity (0.10 PAWC < 0.15
cm3 cm-3) and was soil water-limited
(RFC < 0.6). The advantages of using silvopastoral systems in
semi-arid environments for environmental sustainability are not limited
to improvements in the properties of soils, as these areas are also
important carbon sinks.