In highly weathered tropical soils phosphorus (P) bioavailability to plants is closely associated with soil organic P forms, which in turn are influenced by the vegetation cover. The aim of this study was to evaluate total organic P (Po), labile P fractions and microbial biomass P in soils under Acacia auriculiformis and Mimosa caesalpiniifolia stands, secondary forest and pasture. The clay-adjusted average content of total Po and labile Po were 375 mg kg-1 P and 40.2 mg kg-1, respectively. The […]

Quantifying the relationship between physical and mechanical soil properties can contribute to the development of pedotransfer functions that allow estimating hard-to-measure soil properties. The objective of this study was to evaluate the interrelations between susceptibility to compaction and load support with some physical properties of soils from Southern Brazil. Penetration resistance, moisture, bulk density and compressibility of six soils were evaluated. In a model including soil moisture and bulk density as independent variables, the relation with penetration resistance values obtained […]

The ion exchange resin method used in some laboratories in Brazil requires soil grinding for the determination of available P. As a consequence of grinding, the extraction of internal labile P in aggregates is expected, increasing the concentration of available-P. On the other hand, finer grinding increases the exposure of soil particle surface, which creates additional sites for further P adsorption. The aim of this study was to evaluate extraction efficiency available-P by Mehlich-1, and anion exchange resin in beads […]

Inadequate soil management has led to the degradation of physical, chemical and biological soil properties. The purpose of this work was to evaluate the yields and physical and chemical soil properties of a dystropherric Red Latosol (Oxisol) in the third year of a crop rotation that included green manures, with soybean or corn (summer) and common bean (winter) crops. The following green manure species were used: velvet bean, millet, sunnhemp, pigeon pea, cultivated under conventional tillage and recently adopted no-tillage. […]

Soil organic matter is the largest carbon reservoir in natural systems. In such systems the carbon quality and stability can be estimated based on the increase of humified fractions which, among other factors, is related to the balance between losses and accumulations involving oxidation and reduction reactions of the soil organic matter. The objective of this study was to evaluate the electrochemistry of humic acids isolated from soils cultivated continually with sugar-cane, with or without pre-harvest burning and annual vinasse […]

In spite of the normally low content of organic matter found in sandy soils, it is responsible for almost the totality of cation exchange capacity (CEC), water storage and availability of plant nutrients. It is therefore important to evaluate the impact of alternative forest exploitation on the improvement of soil C and N accumulation on these soils. This study compared pure and mixed plantations of Eucalyptus grandis and Pseudosamanea guachapele, a N2-fixing leguminous tree, in relation to their effects on […]

Little is known about the changes in different soil organic matter (SOM) fractions under short-rotation eucalypt plantations. This study aimed to evaluate the impact of eucalypt cultivation on C stocks of several organic matter fractions in soils previously covered with degraded pasture, as well as to identify which SOM fractions are more sensitive indicators of land use change impacts. The study was conducted at two sites (Belo Oriente and Virginópolis) with commercial short-rotation eucalypt plantations in the Rio Doce Valley […]

This study aimed to evaluate the differences in carbon and nutrient cycling and balance in two plantation systems of forest species native in the Atlantic Forest. The plantation systems consisted of 22 year-old mixed stand and pure stands of six hardwood species (Peltogyne angustiflora, Centrolobium robustum, Arapatiella psilophylla, Sclerolobium chrysophyllum, Cordia trichotoma, Macrolobium latifolium) native to the southeastern region of Bahia, Brazil, that were evaluated from August 1994 through July 1995. As references, the study included a natural forest and […]

Soil resistance to penetration (PR) frequently reduces plant root growth. PR increases with soil bulk density (Bd) and decreases with soil moisture (θ), and the mathematical description of the relationships of PR with Bd and θ determines the soil penetration resistance curve (SRC). The objective of this study was to quantify the SRC of an Oxisol under different land use practices and to use it to describe soil physical degradation. Four areas were selected: (a) native forest; (b) pasture cultivated […]

Land application represents an efficient alternative for disposal of biosolids. However, depending on the origin (urban and/or domestic) and the treatment system, biosolids may contain high amounts of heavy metals, which can gradually build up in the soil. Soil chemical amendments in contaminated areas can reduce the bioavailability and mobility of heavy metals and, consequently, minimize the risks of their adverse effects on the environment. The objective of this study was to evaluate the effects of four chemical amendments [calcium […]