Estudo de lixiviação de nitrato, por modelagem, num cafezal em Santo Antônio do Jardim SP

Abstract

Crop growth and development requires the presence of nutrients in adequate quantities. Nitrogen fertilizers have been widely aplied to provide proper crop nutrition. However, large-scale application of nitrogen fertilizers causes environmental impacts by increasing the probability of groundwater contamination, greenhouse gas emissions and wasting financial resources. The objective of this work was to evaluate the moisture dynamics and nitrate leaching in a Latossolo Vermelho Amarelo coffee plantation. Soil characterization data, cultivation practices and microclimatic data were obtained in a coffee plantation by Arabica Catuaí coffee located in Santo Antônio do Jardim, São Paulo. Were obtained from soil samples data describing the physico-hydraulic characteristics that affect the dynamics of water and solutes in the soil. Transport parameters and boundary conditions were entered in the HYDRUS 1D model for the parameterization in order to predict water and nitrate flow. Model performance was evaluated based on residual analysis and mean square error. The direct simulation did not have a good fit for water retention and the deviations were biased. By the use of field water volumetric content data and the inverse simulation routines, a good prediction of the water volumetric content was indicated by the low mean square error (0.04) and non-trend residues. A simulation of nitrate movement after fertilizer application was made. A nitrate concentration of 5.1 mg.cm-3 at a depth of 110 cm at the end of 92 days was estimated. The total flow of leached nitrate at 92 days was estimated at 131.8 mg.cm-2 (28% leaching rate). The HYDRUS 1D software was efficient for simulating soil water volumetric content in Latossolo Vermelho Amarelo and the equilibrium model for soil solute transport was apparently efficient for estimating nitrate displacement. The high potential of leaching indicates that the application of fertilizers in coffee plantations in this soil with the climate of this region presents environmental risks due to the possibility of groundwater contamination and risks of financial losses.