Modelagem e geoprocessamento aplicado ao planejamento de sistemas agrícolas conservacionistas: desenvolvimento de método e ferramenta computacional

Abstract

The deficiency in the management of agricultural areas causes problems of economic

and environmental order. Many times the terraces dimensioning methods have results with reduced

horizontal spacing, discouraged their adoption and causing erosion problems, and consequently

loss of soil, water and nutrients. The soil loss calculation models can be used for the design of

these structures, considering the displacement of soil lower than its natural formation rate,

controlling the erosive process. However, the use of these models is hampered by the lack of data

bases and tools that simplify their use. Concomitantly conservation planning can be integrated into

agronomic management, enabling the optimization of the use of agricultural land and of the

equipments, conciliating the economic and environmental aspects. In this sense the present study

aimed to evaluate the cartographic quality of altimetric surveys carried with GNSS RTK receiver

onboard in quadricycle; develop a terrace in level spacing calculation method, using the soil loss

calculated by USLE; a model of dimensioning agricultural systems, involving the use of terraces as

rural roads, plots division, and generation and planting lines; analyze the accumulation of runoff on

sugar cane lines for different furrow depths and the spatial variability of relief; and finally, develop

a computational tool using the method and model. The altimetric data collected with quadricycle

met the Class A pattern of cartographic accuracy, for the preparation of cartographic products with

vertical equidistance of 0.30m. The terrace spacing calculation method reduced by up to 83.0% the

total length of terraces; the agricultural systems dimensioning model enabled a reduction of up to

51.6% in the number of operations as well as increasing the average length of the lines and

reducing the area for the use of rural roads, which increases the efficiency in the machinery use

and in the use of agricultural area. The evaluation of the runoff volume accumulation in the

planting lines due to the furrow depth found large storage capacity, reaching values of up to 158.1

m³ ha -1 , averaging 95.8 m³ ha -1 to furrows with 0.3m depth, resulting in a reduction of up to

10.1centimeters at the height of the terraces. The developed computational tool proved to be easy

to use, and successfully completed the design of the plots, planting rows and terraces.