4.1 Land Use and Occupation
The predominant crops in the inspected sections of the watershed were
Pasture, Natural Forest and Coffee. The natural forest, considered the
best vegetation cover, is present in an area corresponding to 21.16% of
the surface of this stretch of Rio do Peixe watershed., In a watershed
of 11,000 ha in Botucatu, with relief similar to Rio do Peixe watershed,
Santos et al. (2014) found 1,109 ha of natural forest, corresponding to
9.95% of the watershed area. These results correspond to less than half
of the results of the present work, indicating that, in this stretch of
Rio do Peixe watershed, the forest is much more preserved.
In what concerns the pasturs of the studied area, there is an occupation
of 30,472 ha, amounting to 60.81% of the total area of the watershed
(Table 1). Such results are similar to those of Lima et al. (2004), who
inspected 43,228 ha of pasture in a watershed in Ilha Solteira, SP,
where it amounted to 66.79% of the total surface. In this work, one of
the positive examples was the restoration of an agricultural property in
Ocauçu, SP, with a degraded pasture area of 500 ha. After carrying out
this work, these 500 ha were transformed into an agricultural area with
no-tillage system, intended for annual crops, with rotation: brachiaria
straw, soybeans, corn and wheat in winter (crop change and soil
management). This represents the implementation of a new conservationist
technology in the region.
4.2. Vegetation Cover Indicators
The images from Google Earth® Pro confirmed the effectiveness of the
actions implemented in the pasture area where an erosive process had
taken place (Figure 2A and 2B). An plan of agri-environmental adequacy
was applied, to contain the erosive processes and control the erosion in
the area, which was accomplished with the construction of containment
basins on the pasture areas. There was an improvement in the visual
aspect of the area, compared to soil conservation strategies, in which
case it was proven that pasture management with the use of containment
basins favored the restoration of the area, and the return of potential
soil productivity.
Figures 2C, 2D, 2L and 2M effectively demonstrate that the change in
management of coffee plantations provided a positive change in the
landscape. In addition to improving the landscape with more intense
vegetation cover (Figures 2D and 2M), there was an improvement in
potential crop productivity. In the coffee culture, what contributed to
the improvement of the soil conditions was the adequacy of the crop to
the relief, and recovery of soil fertility. The soil conservation
techniques applied in this case were sufficient to control the erosive
processes.
Image comparison of Figures 2E and 2G showed that the agricultural
terracing built in the area under scrutiny was efficient in controlling
erosion processes at the property. According to Araújo et al. (2009),
with the use of appropriate management measures and erosion mitigating
actions, along with the restoration of the impacted areas, there will be
an improvement in water quality and control of sediment production,
minimizing silting and consequently, there will be an almost complete
environmental restoration.
The comparison of aerial images, from before (T1) and after (T2) the
treatment, was used to assess the efficiency of the results obtained.
The same method was used by Bezerra et al. (2012), who used it to
compare the vegetation cover and the water potential in the soil, with
the purpose of monitoring and restoring degraded areas. The photographic
comparison, in addition to a supervised classification, allowed to
monitor the development of the vegetation cover with grasses, as well as
their relation to the soil’s water potential. According to Menezes et
al. (2009), the use of remote sensing permitted the identification of
areas already affected by inadequate management, with degraded pastures.
These authors also highlighted the fact that native vegetation has been
largely converted into pasture. Figures 2K and 2O illustrate the
mechanical control of erosions, as the construction of dams and terraces
transforms the previously degraded landscape into a pasture with
productive capacity (Figures 2J and 2N). Figure 2J shows an old and
eroded road that carried sediments to the bed of Rio do Peixe, and which
was corrected with the construction of terraces (Figure 2K).
It is noteworthy that there are practices focused on the conservation of
pastures, which represent a large part of the Rio do Peixe watershed
section in addition to promoting important benefits for soil
conservation. This can further enhance the income for producers since,
with conserved pasture, there is a higher volume of biomass and,
consequently, a chance for higher animal density. An example of this is
the case of pastures recovered by Integrated Crop-Livestock Systems
(LIS) where the management was modified through the replacement of the
varieties of grass, and by providing pasture with quality plant mass
during the dry periods. This resulted in an occupancy rate of five
Animal Units (AUs) per ha, as evidenced by the evaluation of 10
properties, where there was an average growth of 31% in the occupancy
rate, compared to the original situation, i.e. before carrying out the
inspection work. This is corroborated by the study of Albernaz & Lima
(2007) who evaluated two sub-watersheds occupied by pastures in Lavras,
MG, adopting conservationist practices: level planting, terracing,
containment basins and liming maintenance. They have also suggested that
at Ribeirão Santa Cruz sub-watershed (SW), more conservation practices
are adopted than at SW Água Limpa, and the exposure of the soil to
degradation was higher at SW Água Limpa. A similar result was observed
by Zolin et al. (2011), who documented that the largest relative
reductions in soil loss occurred under scenarios of conserved pasture,
indicating that the optimization of soil conservation can be
accomplished by adopting conservationist management practices for
pasture recovery. According to Rodrigues et al. (2015), who analysed the
role of vegetation in water interception and erosion control, at Rio
Paraíso watershed, in São Manuel, SP, and the uncovered soil showed a
98.09% increase in sediment production, when compared to soils with
vegetation cover.