Efeito do hidrogel em plantios de mudas nativas do cerrado para recuperação de área degradada pela mineração no Distrito Federal

Abstract

The hydrogel can act as a soil conditioner, helping in retaining moisture in the soil and the water supply to plants, especially in times of drought, facilitating the survival and development of plant species. Thus, the hydrogel can contribute to the success of projects of recovery of degraded area. Thus, the present study aimed to evaluate the effect of hydrogel in the soil properties, in the survival and growth of 11 species native to the brazilian savannah, in the area degraded by mining of sand in the brazilian savannah biome. We carried out the planting of 1,210 seedlings of 11 species native to the brazilian savannah (Acacia tenuifolia, Ceiba speciosa, Copaifera langsdorffii, antisyphilitica Cybistax, Dalbergia miscolobium Dipteryx alata, Handroanthus serratifolius, Inga laurina, Eugenia dysenterica, Sterculia striata and Tabebuia roseoalba) following the Native Biome Model. The experiment consisted of 12 plots, six in the control group and six in the treatment group, however, one of the plots of the treatment group was lost by erosion, leaving the experiment with a total of 11 plots. Treatment consisted of applying of 400 ml of hydrated hydrogel for planting hole. During 28 months, on four occasions (at 2, 8, 22 and 28 months after planting) data of height (H), collect height diameter (CAD) and survival of plants were collected. We analyzed seedling growth through increment data in CAD and H and survival by counting living individuals in each sampling. After 32 months of planting occurred collect of undisturbed soil samples to study the physical and deformed soil composed samples for the study of soil chemistry. These samples were collected in the pits of random individuals of the species C. langsdorffii of the control group and the treatment group and outside of the planting hole. Principal component analysis (PCA) and non-parametric Kruskal-Wallis and Mann-Whitney test was performed. Tests revealed no statistically significant difference between the treatment and control groups in both soil properties and in the growth and survival, indicating that 400 ml of hydrogel were not sufficient to promote the effect in this variables. But we found a statistically significant difference between the 11 species used in planting, demonstrating that they behave in different ways with each other, independent of the use of the hydrogel. In addition, MannWhitney test indicated that the parameter by which themselves differentiate the species was survival. Forest species grew faster than the savanna, as provided by Native Biome Model, however 28 months were not enough to promote the shading of the area and the elimination of invasive grasses. The overall survival in the study was 71.6% and, C. antisyphilitica, D. miscolobium and E. dysenterica had the lowest survival rates. While C. langsdorffii. and I. laurina rates are higher for the set of variables and survival increments in height and diameter at the collar. As for soil physical properties, soil moisture averaged 7% and the chemical indicated acidic soil of low fertility and low levels of organic matter, phosphorus, and total bases.