Os discursos e contradiscursos sobre a algarobeira (Prosopis sp.) no cariri paraibano.

Abstract

In the semi-arid regions the environmental degradation is resulted of several factors, such as: climatic variations, lost of the vegetation covering and other atrophic activities. In the Brazil Northeast Region, where is located the Caatinga biome, which is the one that suffer so much because of these factors. The most part of the vegetation covering of this region is composed by caatinga and nowadays the most part of it is formed by Prosopis. It was brought to Brazil in the 40s, after that arrives in the Northeast in Serra Talhada city in Pernambuco, in the middle of 1970, the government stimulates farmers to take out caatinga native vegetation and substitute it by Prosopis because it was always green and could be used for everything. However, by the years, it did not stimulate the farmers anymore and the plant that came to minimize the problems during the dry period in the region is now considered a problem. To make clear the social-environmental questions about Prosopis the research was divided in two parts: in the first one it was carried out a research in the cities of Boqueirão, Cabaceiras e São João do Cariri, in Paraiba State Brazil, where it was interviewed 306 farmers, 102 in each city; the second one was carried out in a place located at the Campina Grande Federal University with the objective to evaluate Prosopis hydric consumption thought the replacement of évapotranspiration fraction, fresh water, it was adopted five water depth levels (20, 40, 60, 80, 100), height of plant, stem diameter and root length were also evaluated, according to évapotranspiration levels. The irrigations were done each three days. Interviews with the farmers were made in which were observed that the highest incidence of Prosopis were in the rural areas less than 5 ha and that it is used as animal ration and wood, this r is used as energy resource such as cool and firewood. Considering that it was applied 17.165 liters of water during the research and that the évapotranspiration in the same period was 16.954 liters, the less value of évapotranspiration 138,54 liters was observed in the reposition level T (20%) and the highest one was 863,86 liters at the level of T (100%). The height of plant and steam diameter increased according to the increase of water level and according to the time. The total productions of dry biomass was 36,05kg with water efficiency of 0,47 g/kg, gram of produced dry biomass to each kg of applied water. Of out 180,67 km corresponding to the total length of root the biggest average was equal to 5575,15 m observed in at water level T (60%). It was observed that the soil chemical composition analysis at the end of the research were better when compared with the ones at the begin of the research, it was observed reduction in the pH level and an increase in the levels of nitrogen and organic matter.