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.