Solubilidade de fertilizantes organominerais peletizados a base de biossólido e torta de filtro

Abstract

In addition to plant essential nutrients availability, soil fertility has been also connected to many other aspects due to modernization of agriculture. One of the relevant aspects is the sustainability of the system. In this sense, the use of waste has been a very important demand. The use of filter cake has already been a common practice in sugarcane mills, as well as the use of sewage sludge tends to increase due to its nutritional value to soils. The objective of this study was to analyze the soil chemical changes and the solubility of nutrients from organomineral fertilizers pelletized with biosolids and filter cake. The experiment was conducted from 09/19/16 to 11/19/16 under greenhouse conditions at the Federal University of Uberlândia, Umuarama campus. It was arranged in a completely randomized design, with 4 replicates and 3x5+1 factorial scheme, comprising 3 fertilizers: organomineral fertilizers pelleted with different organic residues (biosolid or filter cake) and mineral fertilizer; 5 fertilizers doses, referring to 60%, 80%, 100%, 120%, and 140% of the standard P 2 O 5 dose for maize crops, and a control treatment without fertilizer application. Fertilizer formulations were performed at concentrations of 5-17-10 (+ 10% TOC). The organomineral fertilizers were pelleted and the minerals were coated with an organic base. An incubation test was carried out using a sandy-loam soil collected at the Glória experimental farm, Federal University of Uberlândia. Each experimental plot consisted of a plastic pot containing 1 kg of air-dried fine soil and the source of fertilizer in its proper dose. The samples of fertilizers were packed on a mesh placed about 1 cm below the soil surface. The sources were incubated during 60 days and three subsamples collections were performed at 5, 15, and 60 days of experiment. Chemical analyzes were carried out to determine soil acidity and nutrient factors. It was observed that organomineral fertilizers pelletized with biosolids or filter cake did not acidify the soil, requiring less frequent soil liming. Organomineral fertilizers based on biosolids and filter cake have a buffering effect on the soil, maintaining pH stability. The organomineral fertilizer pelletized with biosolids promotes a significant reduction in the soil aluminum saturation. Organomineral fertilizers pelletized with biosolids or filter cake have slow release of nutrients. Pelletized organomineral fertilizers allow more balanced base relations in the soil, resulting in a more adequate balance of nutrients with higher base sum, cation exchange capacity and base saturation.