Desenvolvimento do horizonte A associado a pau-d’arco-roxo (Tabebuia impetiginosa Mart. ex DC.) e eucalipto (Eucalyptus urophylla S. T. Blake)

Abstract

The cultivation of planted forests is an alternative to mitigate the negative effects of logging for industrial purposes, but as plant and soil organisms have a highly interactive relationship, it is necessary to analyze how this environment behaves in the face of this new agrosystem configuration. In this sense, the present work aimed to analyze the development of superficial horizons after a period of 9 years under the species Pau-d'arco-roxo (Tabebuia impetiginosa) and Eucalyptus (Eucalyptus urophylla); and compare with the soil under spontaneous vegetation, in an experimental area located in the municipality of Acaraú, through morphological aspects and chemical attributes. In each of the three treatments, the description of color, thickness, depth and structure of 7 profiles was carried out. The material from the first three layers / horizons of the soil was collected in all points, in a deformed manner, totaling 63 samples analyzed for the total organic carbon content and potential soil acidity. The soils presented a sequence of horizons Ap1 - Ap2 - EA or AE. The color data shows an increase in value and chroma with depth. The subangular block-type structure occurred in all horizons in the three treatments. The treatment with Pau-d'arco-roxa had intermediate characteristics in the different aspects analyzed compared to the other two coverings, standing out in the degree of structure, which was characterized as stronger in the first two horizons. The control area stood out in the levels of total organic carbon in Ap1 and in the development of more pronounced sizes in the transitional horizon, but in contrast, a structure in general with a weaker degree, probably due to the low quality of the organic matter generated from the vegetation. predominantly tender. The treatment with Eucalyptus showed greater potential acidity, possibly associated with the material deposited on the soil in these plots, which is in constant but slow decomposition, as it is more resistant, rich in lignin and with a higher C / N ratio in comparison to the other wastes contributed. The results show that, after 9 years of implantation of the treatments, some characteristics of horizon A among the studied soils presented significant difference, showing the distinct influence of each species on the soils of the experimental area.