Desempenho agroeconômico de um módulo de cultivo orgânico diversificado de hortaliças com foco no balanço de nitrogênio

Abstract

Agriculture has reached high levels of development with a fine line between the benefits and the harm caused by the intensity of exploitation of natural and social resources. Therefore, the interest of consumers, producers and technicians has emerged for production of quality products with less environmental impact, that carry sustainable concepts in their productive trajectory. In order to meet the demand of this new market based on sustainability and scientific parameters of quality, an experiment was implemented in 2010 at Fazendinha Agroecológica Km 47. The long-term experiment called the Module of Diversified Cultivation of Organic Vegetables tested the hypothesis that an intensive organic crop of vegetables is sustainable under edaphoclimatic conditions of Baixada Fluminense, in the State of Rio de Janeiro, Brazil. Agroeconomic indexes and nutritional balances were generated and observed every agricultural year. The results suggested that there would be no great losses of nitrogen (N), a fundamental nutrient for viability in agroecological crop management. In the attempt to evaluate the gaseous losses of N and to generate unpublished scientific results in the scope of the organic systems of production, a study of the gaseous losses of N-NH3 in the area of greater cultivation of vegetables of the Cultivation Module was initiated, in the agricultural cycle of 2018/2019. The research tools employed were: a) monitoring inputs and outputs of agricultural inputs, harvests and production system work; b) study of the volatilization of N-NH3 with the use of chambers called SALE (semi-opened static chamber); c) analysis of temporal/spatial variability of fertility and volatilization through geostatistical techniques. The organic production system was monetarily feasible if the annual production (15673.27 kg of food) was sold at the Carioca Fair of Organic Fairs and in the institutional market by the National School Feeding Program (PNAE). In a commercial market scenario (CEASA / RJ), even when the cost-benefit assumes a value greater than 1, which is considered profitable, the monthly revenue is low. This reinforces the importance of consumer awareness, diversification of marketing channels and the social organization of farmers as ways of guaranteeing fair prices. There is an urgent need to research on the technological development of agricultural inputs and alternative management practices with low cost that will increase the profitability on olericulture. The loss of N-NH3 found can be considered insignificant when compared to the use of mineral fertilizers. In the cultivation module the nitrogen loss rate was slightly more than 3%, while in experimental trials with urea, also in sandy soils, indicate losses of up to 67.9% It is worth mentioning that in addition to being an experiment that tends towards the natural balance, the management adopted by the Cultivation Module aims at conservation practices, with great incorporation of organic matter in the soil and use of fertilizers that add greater benefits than only soil fertility.