Influência da aplicação de biofertilizante e matéria orgânica em algumas propriedades físcas de um solo da Chapada do Apodi - CE

Abstract

The use of liquid biofertilizers as a new alternative for improving soil quality in the application period all over the world. However, little is know about the effects of its application on the physical properties of soil. The objective of this study was to evaluate the effects caused by the application period of biofertilizer and organic matter on some physical properties of Inceptisol eutrophic, located on Apodi Tableland, in Quixeré-CE, Brazil, with loamy and clay loamy texture, in the 0-5 and 15-20 cm layers, respectively. The experimental design consisted of randomized plots, with five treatments and four replications. The treatments studied were: native forest (NF), and two growing areas. In these areas samples were taken from two sites: 1) the distance between each plant row, where there was deposit of debris (A1R and A2R), and 2) at each plant row (drip), which receives application of biofertilizers, having been made application of biofertilizer in an area by five years (A1G) and second area for 18 months. The results showed that cultivation led to the decrease in soil total organic carbon (TOC) at 0-5 cm layer. The higher content of TOC in the NF system resulted in a decrease in the particle density in the 0-5 cm layer. The highest concentration of stable aggregates occurred in the class of 4.76-2.00 mm in the 0-5 and 15-20 cm layers. Mean weight diameter (MWD) and the index of aggregates stability (IEA) increased with the time of application of biofertilizer at both depths; the treatments MN and A1R showed the highest DMP and IEA, in the 0-5 and 15-20 cm layers, respectively. The application period of biofertilizer and organic matter did not promove significant differences in bulk density, porosity, macroporosity, liquid limit (LL), plastic limit (LP), sticky limit (SL) and plastic index (IP) among treatments and depths studied. The model for prediction of the LP from the point of inflection of the curve of water retention overestimated the values of LP. The curves of water retention in all treatments described virtually the same behavior, maintaining a clese relationship with soil structure. The S index had values over 0.050 in the all treatments and depths. There was a linear correlation between the S index and bulk density, porosity and microporosity in both depths. There was no significant correlation between the S index and the content of COT neither any other parameters of soil structure, such as macroporosity, DMP and IEA.