Aluísio Granato de Andrade

Erosão superficial em argissolo amarelo sob cultivo perene e com pousio florestal em área de relevo montanhoso

The mountainside region of Rio de Janeiro (Regiao Serrana Fluminense) has many freshwater springs and the State´s largest remaining area of Atlantic Rainforest. It is important to know and control the harmful effects of soil erosion in order to harmonize environmental preservation with the intensive vegetable production in this mountain region. The purpose of this paper was to study soil loss by erosion and the hydrological components in an area with a slope gradient of 65 cm m-1. The study area consisted of plots with vegetable production in a rotation system, with banana and of a five-year-old forest fallow in a small watershed of the municipality of Bom Jardim. Three experimental plots of 88.0 m2 each (4 x 22 m) were installed to monitor soil loss, runoff and soil water dynamics. Soil characterization was performed by physic, chemical and mineralogy analysis. The highest soil erosion loss was recorded in the critical period between September and March, with approximately 30t ha-1 yr-1 from the annual crops and 10 t ha-1 yr-1 from forest fallow in the first year of development. The soil properties that correlated best with erosion were texture and the soil aggregate stability index. It was concluded that the time of soil use for vegetable cultivation and forest fallow can affect the maintenance of natural resources in this area, reducing slope stability and accelerating the erosive processes.

CARBON STOCKS IN MINED AREA RECLAIMED BY LEGUMINOUS TREES AND SLUDGE

Few studies have been carried out on aboveground (or belowground) and soil/substrate C accumulation in severely degraded areas, such as mined areas. The present study was developed in order to find a recovery strategy for a mined area and characterize its potential for C sequestration by planting two nitrogen-fixing Brazilian tree species (Mimosa caesalpiniifolia Benth and M. bimucronata (DC.) O. Kuntze). Sewage sludge was included in the experimental design. An experiment under randomized block condition and 2 x 5 factorial design with four replications were defined and carried out, in Rio de Janeiro State, Brazil. The treatments consisted of a combination of both tree species and five sewage sludge doses (0, 2.85; 5.70; 11.40 and 22.80 Mg ha-1). M. caesalpiniifolia grows better (p<0.05) in reclaimed areas than M. bimucronata, even though neither the height nor the basal area of both species responded to the sludge application. Carbon stock in the tree trunks differ between species (27.3 and 14.3 Mg ha-1, for M. caesalpinifolia and M. bimucronata, respectively), and was influenced by the doses of sewage sludge, whereas the soil carbon stock (0-10 cm) did not differ between species and doses (12.0 and 12.2 Mg ha-1, for M. caesalpiniifolia and M. bimucronata, respectively). Soil fertility in the degraded site was found to be improved by legume trees six years after planting, with a small influence of the sewage sludge level. Mined areas recovered with legume trees can sequestrate significant amounts of C both in aboveground biomass and soil in a short period of time.

BANCO DE SEMENTES DO SOLO PARA USO NA RECUPERAÇÃO DE MATAS CILIARES DEGRADADAS NA REGIÃO NOROESTE FLUMINENSE

The objective of this study was to characterize the germination and species diversity of the seed bank of a fragment of riparian forest located at the Experimental Station of PESAGRO-RJ, in Itaocara city, RJ state, and evaluate its potential use in nucleation techniques. Samples of soil and soil + litter were removed with iron corer (0.25 mx 0.25 mx 0.05 m), at five different points of the fragment, each 10 m from the bank of Paraiba do Sul river. At each point three soil samples and three samples of soil + litter were collected. The material was made to UENF and arranged in plastic trays (25 cm in diameter and 9 cm tall) in the greenhouse. The treatments were arranged in randomized and compared by F test (5%), with 15 replicates of each treatment, represented by a tray. For four months, 473 individuals distributed among herbaceous, shrub and tree species were recorded. The seed bank is composed mostly of herbaceous species, highlighting the Pteridium arachnoideum (Kaulf.) Maxon, with 58 seedlings germinated. Among the shrub and tree species, the highlights Piper sp. and Trema micrantha (L.), with 56 and 32 seedlings germinated, respectively. The seed bank in the soil + litter, had a lower number of species, with no difference in the number of seedlings germinated. Both the soil and soil + litter have potential for use in nucleation techniques.