Brazilian Agriculture

Conservationist agriculture is responsible to appropriate physical, biological and chemical agricultural conditions for crops to express their genetic productive potential (ZACANARO; KAPPES, 2014). Until the 1950s, the production of Brazilian agriculture depended almost exclusively on the natural fertility of soils, which is mostly low due to the high acidity and the presence of toxic trivalent aluminum contents for the main crops. In addition to these problems, we also highlight the low availability of macronutrients (N, P, K, Ca, Mg and S), micronutrients such as Zn and Cu, low CEC and, P fixation in tropical regions, which makes it unavailable for cultures since P is adsorbed by electrostatic or covalent mechanisms (ALCARDE et al. 1991). The practices of soil acidity correction and fertilization contributed significantly to the improvement of soil fertility over the years (BERNARDI; MACHADO; SILVA, 2012). Another concept incorporated to the management of fertilization is the fertilization of crops systems which can be defined as a technological resource that aims to fertilize the production system as a whole, instead of fertilizing only a single crop (OLIVEIRA, 2010). Fertilization of crops systems consists of more intensively fertilizing more responsive crops such as corn, cotton, beans and tomatoes and using residual fertilization for less responsive crops, such as soybeans. Residual nutrients are considerable relevant (ALTMANN, 2012). Borin (2013) considers essential for the fertilization of systems, the results of soil analysis (available contents), as well as the nutrient credits left by previous crop residues, the productivity expectations for calculating nutrient extraction and exportation, the demands the nutrient efficiency of each crop, the efficiency of fertilizer use and the evolution of soil fertility. For Altmann (2010), in no-tillage system, nutrient losses are significantly lower when compared with conventional agriculture. It is possible to fertilize the production system in order to better exploit the most responsive crops, in addition, it is recommended to increase the fertilization for crops that have the highest responses to it and explore the residual effect of the soil. In no-tillage, crop rotation is used in which the cover crop precedes the main summer crop, the possibility of fertilizing the system and not only the main crop. Part of the fertilizer is applied pre-planting to the cover crop, which will be desiccated and, consequently, these nutrients will return to the main crop (EMBRAPA, 2003). Results obtained in Turvelândia (Goiás state, Brazil) indicated that the millet cultivated as a cover for cotton crop responded to potassium fertilization up to 60 kg.ha-1 K2O. This better use occurred when the fertilization of the previous crop was made in total area, and not located only in the planting furrow (EMBRAPA, 2003). In system fertilization, the residual effect of previous fertilizers on subsequent crops, the nutrient cycling credits is considered. The residual nutrient efficiency on plant yield depends mainly on some factors such as climatic conditions, soil type, nutrient adsorption and removal capacity (MATOCHA et al., 1970; MALAVOLTA et al., 1974; FASSBENDER, 1980). In successive cropping systems, when previous crops are fertilized, the residual effects, especially of phosphate fertilizers, are noticeable (SILVA; SILVA FILHO; ALVARENGA, 2001). Fertilizer recommendation is more flexible through integrated pre-planning, fertilizing the main crop with higher response potential, even in excess of the required quantities and minimizing or eliminating application to the next crop with lower fertilizer response (BORIN, 2013). Luiz Gustavo Batista Ferreira is Agronomist Engineer graduated at UEL - State University of Londrina and, also, Master of Science (IAPAR, Brazil). Printed in The United States of America. Higher quality of print. Series: International Research Publication on Technological Agriculture.