Rochagem e biofertilizantes como fontes de nutrientes para grandes culturas: efeitos na produtividade e no solo

Abstract

Brazil is the fourth world consumer of fertilizers and very dependent on imports. With the crises that the cost rising of these inputs generated between 2007-2008, the interest for alternative nutrient sources raised and the use of rock powders as sources of minerals and nutrients for soils became more widespread. Organic fertilizers also got pronounced status, and both started figuring into research projects on the sector. The present study brings results of a long-term research that aims to evaluate alternative fertilization techniques used by organic farmers from Guarapuava`s region, Paraná State, with combinations of basalt rock powder and biofertilizers, on the soil chemical characteristics and production of field crops. The study was realized at the Experimental field of the Agronomy Department, at Midwest State University (Guarapuava), in an Oxisol area between 2005-2011. A random block design was used, with four fertilization treatments: T1 - NPK rate recommended for the crop; T2 - T1+2,000 kg ha?¹ of basalt rock powder (PB); T3 - 4,000 kg ha?¹ of PB; T4 - 1,000 kg ha?¹ of "independence fertilizer" (AI). Fertilizations T3 and T4 were combined with foliar application of biofertilizers "ecological nitrogen" and "supermagro", respectively. Summer (maize, sunflower, bean, soybean) and winter (black oat, ryegrass, vetch, barley) species were evaluated, and their growth and yield were evaluated, as well as the soil chemical characteristics (annually). Results were submitted to analysis of variance and Tukey Test (a = 0,05). Considering soil fertility and the crops, there was no significant difference between NPK and NPK combined to basalt powder. The use of 4,000 kg ha?¹ of PB + ecological nitrogen and of 1,000 kg ha?¹ AI + supermagro resulted on average yields lower than NPK fertilizations, but still greater than the average yields for the evaluated species at Paraná State for until the fourth cropping year, while maize was preceded by turnip and vetch on winter and oat (or oat+ryegrass) preceded sunflower, bean and soybean. PB + ecological nitrogen fertilization resulted on higher P availability on the soil and, on the whole bunch of crops, better yield than AI + supermagro, which got it`s best performance on sunflower yield, by the presence of B on supermagro composition.