Oliveras Berrocales, Miguel

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    Validación del modelo de simulación índice de nitrógeno (N-index) del caribe en sistemas de producción de hortalizas en el Valle de Lajas
    (2014) Oliveras Berrocales, Miguel; Sotomayor Ramírez, David; College of Agricultural Sciences; Pérez Alegría, Luis; Román Paoli, Elvin; Department of Crops and Agro-Environmental Sciences; Negrón, Edna
    Nutrient losses from agricultural fields are one of the principal causes of environmental degradation. Typical nitrogen (N) fertilizer consumption rates in vegetable production systems and horticultural crops, typically fluctuates between 112 to 253 kg N/ha. This can generate high residual soil N at harvest, and may increment N losses to the environment. The evaluation of N losses to the environment can be evaluated with simulation models such as the N-Index, that can be aid in the identification of N losses and evaluate the effect of best management practices. The N-Index is a simulation model that predicts N losses via surface, leaching, and atmospheric pathways. A field study was conducted to quantify the residual soil N and crop N uptake to validate the N-Index in vegetable production systems in the Lajas Valley in Puerto Rico. Field plots were established with vegetables such as onion (Allium cepa L.), pumpkin (Cucurbita Moschata D.), pepper (Capsicum annum), and tomato (Solanum lycopersicum L.) with two main objectives (i) collect the input parameters for the simulation model N-Index, and (ii) collect the field data to validate the model. Residual soil N and crop N uptake values measured were used to evaluate the model estimations, evaluate the model performance and validate the model. Results obtained from the experimental fields showed a good correlation (p<0.05) between observed and predicted values for residual soil N (r=0.88) and crop N uptake (r=0.99). In the production systems evaluated the N losses ranged between 1 and 4 kg N/ha for volatilization, 18 and 46 kg N/ha for denitrification, 155 and 779 kg N/ha for lixiviation and between 64 and 401 kg N/ha for residual soil N. The N use efficiency ranged between 17 and 39%. The results demonstrate that the simulation model N-Index was valid for the Caribbean region in Puerto Rico, in vegetable production systems.