Modelagem do sistema solo-água-planta-atmosfera e dinâmica de nitrogênio em cultivo de algodão (Gossypium hirsutum) no cerrado baiano

Abstract

The expansion of production areas in the Brazilian cerrado, combined with technification farming systems, made the Brazilian cotton again became representative in the international scenario. However, these farming systems aimed at high income, subsidized by the application of fertilizers can result in environmental and economic impacts. The experiment was developed in western Bahia, municipality of Luis Eduardo Magalhães, the overall objectives were experimentally measure some coefficients to subsidize water modeling in the soil, growth and production of cotton subjected to different sources of nitrogen fertilizers, and to quantify the gas losses to atmosphere of nitrogen fertilizers pastilhados, in the forms of ammonia and nitrous oxide. The dose in all of N fertilizer was 200 kg ha-1. In the first chapter, of growth simulations were performed with the adjusted logistic model according to the GDA and water simulations in the soil, growth and production, with the SWAP-WOFOST model. In the second chapter, the gaseous nitrogen losses were quantified through the static camera system and analyzed by spectrophotometry and chromatography, for ammonia and nitrous oxide, respectively. The logistic model showed satisfactory results for all parameters, with regression coefficient (R2 ajs) of 0.99 for height in all the treatments, the R2 ajs to BT ranged from 0.99 (UP) and 0.98 (Sulf and T) for the BC R2 ajs ranged from 0.99 (UP) and 0.95 (t), BF and LAI had from the R2 ajs 0.92 (t and Sulf) and 0.88 (UP) to BER the R2 ajs ranged from 0.99 (UP and T) and 0.98 (Sulf). Water simulations on the ground with the SWAP showed R2 ajs ranging from 0.58 (Sulf) and 0.39 (T), the index "d" ranged from 0.67 (Sulf) and 0.65 (T), the index "c" ranged from 0.52 (Sulf) and 0.42 (t), considered tolerable and bad, respectively. The growth simulations WOFOST the R2 ajs to IAF ranged from 0.99 (UP) and 0.97 (Sulf), the index "d" was 0.99 in all treatments, the BER presented R2 ajs from 0, 94 (t) and 0.87 (Sulf), subscript "d" ranged from 0.98 (UP) and 0.96 (t), BT simulations presented among R2 ajs 0.99 (UP) and 0.97 (T and Sulf), the "d" index ranged from 0.99 (UP) to 0.96 (T), the index "c" was very good in all the variables and evaluated treatments. The second chapter, seed cotton production of fertilizers ranged from 94.0 ± 22.0 (UPP) to 78.6 ± 22.3 (UPSAeZn), however, the cotton yield in the treatment was higher UPSA, ranging from 6514.2 ± 396.1 and 5551.0 ± 633.7 (UPSAeZn), the same pattern was seen in cotton lint yield, which was 14.4% higher in UPSA treatment than in UPSAeZn. Nitrogen losses via nitrous oxide accumulated from the fertilizers during the production cycle, ranging from 819.0 (UPSA) and 533.0 (UPSAeZn) g N-N2O ha-1, which represents emission factors between 0.29 (UPSA) and 0.15% (UPSAeZn). The volatilization of ammonia accumulated ranged between 61.7 (UPP) and 45.7 (UPSAeZn) kg NH3-N ha-1 for the tested fertilizers, which represented 30.8 and 25.9% of the total applied.