3 RESULTS
The work carried out by São Paulo State Secretariat of Agriculture to apply the legislation, dealt with erosions diagnosis and correction at agricultural properties located at Rio do Peixe watershed, sections of Vera Cruz, Ocauçu and Marília, which correspond to 53 thousand hectares. A great work that “Cares for the Well-Being of Society” and brings benefits to the farmers of Rio do Peixe Watershed. Especially to the entire local people that have benefited from its development, including on improving the quality of water that supplies cities, mainly Marília (216,684 inhabitants) and Presidente Prudente (227,072 inhabitants) that collect waters from Rio do Peixe for public supply.
From 2000 through 2007, Rio do Peixe watershed water was monitored with the respective sample collections and the performance of analyzes that functioned as a control (T1) of the two treatments used.
From 2007 to 2011, 14,076 ha were diagnosed in Vera Cruz city. From 2011 to 2015, 9,027 ha were worked in Ocauçu, totalizing 23,103 ha, in these two sections (I and II), that is, 224 ha per month, the work was carried out by four Agronomist Engineers who worked one week, monthly, for 103 months. In Marília, in 2017, 27,775 ha were diagnosed, which were worked on in 2018, implementing conservation projects on 52 agricultural properties.
In section I, in Vera Cruz, 94 agricultural properties were notified, out of a total of 176 properties. They implemented conservation projects, predicting innovative measures such as improving the vegetation cover of pastures using Integrated Crop-Livestock Systems in the rebuild of them, in crops, adoption of No-tillage and bioengineering, in addition to the usual practices, such as agricultural terracing, containment basins and road readjustment (Figure 2).
In the Ocauçu section II, 82 agricultural properties were notified and in Marília, section III, using the Innovative CDA Methodology (Vischi Filho et al. 2017 and 2018), in just nine months, 20 large agricultural properties and 32 small properties were inspected, with a total area approximately 27.7 thousand hectares. It was diagnosed and evaluated from January to November 2017, in just 9 months of work, 27,775 ha or 3,086 ha per month. This methodology allows the strategy of evaluating, in detail, an area, which, according to the old methodology, would take 103 months to be carried out (8 years and 7 months) and in just nine months the work was accomplished generating time - saving.
Erosions and other soil degradation processes are reported in Table 2. These inspections already carried out received the conservation technical projects for the areas and were implemented.
The results obtained with the changes in soil and conservation management practices of water regarding the improvement of vegetation cover were confirmed by the evaluation of aerial images before the work was carried out – 2002. After the work was carried out - 2013, 2017, 2018 and 2019 - (Figure 2) that is, after the conservationist projects have been implemented, with the areas already recovered and the erosions controlled, starting to adopt conservationist practices that transform soil management, aiming at Conservation Agriculture.
The conservationist practices adopted were improvement of vegetation cover by adopting a system of direct planting in the straw or by improving the management of pastures by correcting and fertilizing the soil, crop rotation, adoption of the Integrated Crop-Livestock System and bioengineering. Mechanical practices were also implanted, such as agricultural terracing, containment basins and divergent channels for the conduction of runoff to the drainage channels and bottom drain, for the control of gully erosion. Disciplinary measures, such as capture, conduction and dissipation for rainwater contributions from dirt roads (Figure 2). It is important to highlight that after the notifications of the farmers, there was an awareness that they started to worry and make conservation practices a preventive and routine action on the properties. This work to inspect the use and conservation of the soil is important not only for the soil and water preservation, however, also for the rural producer to earn more money with his activity, a fact that can be proven by analysing Table 3. Where in most of the agricultural properties worked with the recovery of pastures, farmers had an increase of 31% in the occupation rates of these areas and with this, they will have a higher income and a greater profit in their activity.
The results of the ”in loco” survey for land use and occupation (Table 2) show that the following crops predominate at the Watershed are pastures with 30,472 ha, coffee with an area of ​​2,798 ha, fruit (mango, coconut, and citrus) with 136 ha, eucalyptus with 95 ha, vegetables with 60 ha, passion fruit with 15 ha, crops of the annual cycle (corn and beans) with 181 ha, sugar cane with 37 ha, and in the environmental condition, natural forest, with 10,606 ha that cover the slopes of the formation known as ”Itambé”.
The improvement in water quality caused by the control/minimization of erosive processes and sediments carried to the watercourse were confirmed by the water quality indicators: Turbidity, Suspended Solids, Phosphorus and Organic Carbon, analyzing the representative graphics of these analyses (Figure 3).
The Turbidity of the water evaluated from 2000 to 2007, considered as before the work was carried out (BEFORE - T1), presented average values ​​of 192 NUT (Nephelometric Units of Turbidity), against the average values ​​of 102 NUT, evaluated from 2008 to 2018, considered as after the completion of the work (AFTER - T2), a decrease of 53% in the average values. For the T1 treatment, the values were higher than the Conama standard (Conama, 1986), which is 100 NUT (Figure 3A), in the average of February and December. In T2 treatment, the average values were 102 NUT, except for February 2009, 2014, 2017 and 2018; October 2009, 2012 and 2018; December 2009 and 2015 (Figure 3B).
The suspended solids evaluated from 2000 to 2007 (T1), presented average values ​​of 297 mg l-1 (milligrams per litre), against the average values ​​of 132 mg l-1, evaluated from 2008 to 2018 (T2), a 44% drop in average values.
The phosphorus evaluated from 2000 to 2007 (T1), presented average values ​​of 0.18 mg l-1 (milligrams per litre), against the average values ​​of 0.14 mg l-1, evaluated from 2008 to 2018 (T2), a 78% drop in average values.
The Organic Carbon evaluated from 2000 to 2007 (T1), presented average values ​​of 9.60 mg l-1 (milligrams per litre), against the average values ​​of 5.19 mg l-1, evaluated from 2008 to 2018 (T2), with a 59% drop in average values.