Abstract :
The north-central semiarid region of Mexico has been exposed to systematic grazing since
colonial times. The grazing impact on rangelands has degraded soils and reduced diversity
and productivity. The most common and detrimental cause of soil degradation is soil erosion
which destroys chemical, physical and biological properties. To determine the effect
of grazing systems on rangelands, several studies were performed. Such studies included
a description of soil profiles to categorize degradation and the evaluation of water erosion
changes due to further degradation processes under grazing systems (rotational, RG and
continuous, CG). The study was carried out on a rangeland of the ejido Pánuco, Zacatecas,
from 2002 to 2005. Soil degradation was classified by identifying 6 groups with similar soil
profiles (GSSP) which were described as: (1) low degradation soil; (2) medium degradation
soil with A horizon lost; (3) high degradation soil without A and B horizons lost; (4) high
degradation soil with in situ development; (5) high degradation soil with calcareous material;
and (6) high degradation soil without development, which is a very shallow soil above
the parental material. Further degradation was determined by soil erosion measurements
performed in the study area and the surroundings. With respect to soil losses their values
were systematically less for the RG system under the native vegetation conditions studied
(P < 0.01). Changes in the production systems may imply a reconversion of the system.
Some changes include a modification in the intensity of use of rangelands, starting with a
new grazing system, as well as changes in technology which may be simulated by GIS
