A model was developed to simulate the Nitrogen and Phosphorus dynamics of pigs in the Rio Grande do Sul state, Brazil associated with corn and soybean production. The model is constituted by an animal sub-model (SMA) and a vegetable one (SMV). The general approaches of SMA are based on technological systems (ST), animal categories, N and P concentrations in diets and its digestive and metabolic efficiencies. The SMA integrates three aggregation levels, constituted by ten compartments for N and P and 300 sub-compartments related to ST and animal categories. The pig production data were divided in seven mesorregions in agreement with the physiographic definitions. The SMV is constituted by corn and soybean sub-compartments. The SMV parameters were based on the cultivated area and in the corn and soybean production of each municipal district. The simulated data show a surplus of corn and soybean in all mesorregions. Annual consumption of corn and soybean meal by pigs on the state is nearly to 1.14 and 0.39 million tons, respectively. Annual volume intake of N and P by the pigs is nearly 36 and 5.7 thousand tons, which 41% of N and 71% of P return to the environment. The simulated values of the different offer/demand sceneries of corn and soybean in Rio Grande do Sul show self-sufficiency of seven mesorregions. The flows of nutrients among soil-plant-animal-soil simulated show that Rio Grande do Sul mesorregions has levels of nitrogen and phosphorus released into the environment by the pigs below the limits imposed by the European Union. The model simulates appropriately the transfers of N and P between animal and vegetable interfaces in pig production in Rio Grande do Sul.
mineral flows; soybean meal; corn; nutrition; pigs
