Influence of sewage sludge, as a substrate, on the recovery of a vegetable community in the semi-arid.
In the northeastern semiarid, environmental degradation, combined with climatic and socioeconomic factors, can cause loss of soil quality and biological diversity, requiring application of techniques that recover and offer benefits to it, providing a nutritional support for the introduced species. This work has assessed the effects of sewage sludge application as fertilizer on the horizontal and vertical structures of a plant community in the seasonally dry tropical forest (caatinga) in the process of recovery. The research took place in the campus of Instituto Federal do Ceará in the city of Quixadá. Three treatments with three repetitions each were applied: raw sludge, sanitized sludge and unmanipulated treatment. There were nine plots containing 20 seedlings each, making a total of 180 seedlings. They were all tagged, and planted away from each other according to specific lengths using the nucleation technique. They also had their ground-level diameter and height measured throughout seven months. As far as the vertical structure is concerned, sanitized sludge was responsible for producing better results in terms of minimum height, average height and height growth rate. In regard to maximum height, there was a difference between sanitized sludge and unmanipulated treatment, but there was no difference between raw sludge and other treatments. After seven months, sanitized sludge produced more individuals with great height, differing from the other two treatments. When the horizontal structure is taken into consideration, minimum and maximum diameters did not increase as a consequence of sludge use; however, differences in average diameter, diameter growth rate and basal area could be noticed from sanitized sludge manipulation. After six months, sanitized sludge produced increased diameters and thicker individuals. Thus, it was observed that the use of sanitized sludge can be a good tool for obtaining quick soil cover in surroundings under recovery.