OIL CHEMICAL CHANGES RESULTING FROM PRE-CROPPING OF CROTALARIA JUNCEA, ASSOCIATED WITH FERTILIZATION BY ORGANIC COMPOST OF DIFFERENT NITROGEN LEVELS

Abstract

The accurate fertilization and nutrient cycling strategies are very important in organic production systems. The aim of this study was to evaluate, changes in soil chemical properties resulting from the use of organic compost with different nitrogen levels, associated with pre-cropping of sunnhemp, after 18 years of organic management. This work was developed in Reference Unit Agroecology in the INCAPER, located in the municipality of Domingos Martins-ES. From 1990 to 2008 studied soil was managed with the application of 15 t ha-1 of compost for cultivation. In 2009 they implemented this experiment with green manure Crotalaria followed by tillage corn-green, in randomized complete block design in a split-plot with three replications. The plots consisted of two treatments (absence and presence of sunnhemp) and the subplots were installed five treatments with fertilization systems based on composts of different nitrogen levels: 1 - No fertilizer (0.0% of N); 2 - 1.5% N in composts; 3 - 2.0% N in composts; 4 - 2.5% N in composts and 5 - 3.0% N in composts. Green manuring with Crotalaria increased the content of P in the soil, but reduced the pH and the concentrations of K and Mg, while not change the contents of Ca, SB, total CEC and total MOS. The presence of sunnhemp pre-cultivation associated with levels of N present in the compounds had no effect on soil chemical attribute. Regarding the experimental initial condition, the area which was not fertilized (level 0% N) had 42% less of K + and 30% less of Mg 2+, reflecting in the reduction of the sum of bases at 10%.