4.1 Land Use and Occupation
The following crops predominate in these sections of 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 area of this stretch of Rio do Peixe Watershed. Santos et al. (2014) evaluating a watershed with 11,000 ha, located in Botucatu, in relief conditions similar to Rio do Peixe watershed, in terms of land use and occupation found 1,109 ha of natural forest, corresponding to 9.95% of the watershed area, a situation that corresponds to less than half of the result found in the present work, showing that in this stretch of Rio do Peixe Watershed, the forest is more preserved.
As for the pasture area, there is an occupation in the studied section of 30,472 ha, representing 60.81% of the total area of the Watershed (Table 1). The results found are similar to those of Lima et al. (2004) who evaluated 43,228 ha of pasture area in a watershed in Ilha Solteira, SP, which represents 66.79% of the total area. In this work, one of the positive examples was the transformation of a property, with agricultural area, located in Ocauçu city, 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). A new conservationist technology that was implemented in the region.
Using the images from the Google Earth® Pro to verify the effectiveness of the works implanted in the pasture area having an erosive process (Figure 2A and 2B). Action of agri-environmental adequacy to contain the erosive processes was implemented and the control of the erosion in the area was accomplished with the construction of containment basins on areas with pastures. There was an improvement in the visual aspect of the area compared to soil conservation, 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.
Analysing Figures 2C, 2D, 2L, and 2M, it can be seen that the change in management in coffee culture provided a positive change in the landscape, inferring that 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 following the level of the ground and recovery of soil fertility. The soil conservation techniques applied in this case were sufficient to control erosive processes.
In Figures 2E and 2G, using the image comparison method, it can be seen that the agricultural terracing built in the area in question was efficient in controlling erosion processes at the property. According to Araújo et al. (2009) the use of appropriate management measures and erosion mitigating actions, with the recovery 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 rehabilitation.
The comparison between aerial images from before (T1) and after (T2) was used to assess the efficiency of the results obtained, a method that was also used by Bezerra et al. (2012) who evaluated by photocomparation the vegetation cover and the potential of water in the soil aiming at the monitoring and recovery of degraded areas, considered that the photocomparation with the supervised classification allowed to follow the development of the vegetation cover with grasses, as well as their relation to soil water potential. According to Menezes et al. (2009) using remote sensing, it was possible to verify the presence of areas already affected by inadequate management on areas with degraded pastures. These authors also highlighted the fact that native vegetation has been largely converted into pasture. Figures 2K and 2O, show the mechanical control of erosions with the construction of dams and terraces that altered the landscape of the place, previously degraded, 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 by building terraces (Figure 2K).
It is important to observe the fact that there are practices focused on the conservation, which represents a large part of the Rio do Peixe Watershed section, besides promoting important benefits for soil conservation, it can be another factor that stimulates the increase in income for producers, once, with conserved pasture, there is a higher volume of biomass and, consequently, the possibility of higher animal density. An example of this statement is the pasture areas recovered with the adoption of the Integrated Crop-Livestock Systems (LIS), where the management of these pastures has changed, replacing the grass variety and providing pasture with good vegetal 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 found before carrying out the inspection work. It corroborates with this information the study of Albernaz & Lima (2007) who evaluated two sub-watersheds, in Lavras, MG, occupied by pastures, according to conservationist practices: level planting, terracing, containment basins, liming maintenance and inferred 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 bigger at SW Água Limpa. A similar result was observed by Zolin et al. (2011) stating that the biggest relative reductions in soil loss occurred on scenarios with 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.