Volume 23, Number 2, 1999

The impact of winter cover crops prior to no-tillage corn on aggregate stability was evaluated throughout the agricultural year of May 1991 – May 1992, in a Hapludalf (Red-Yellow Podzolic). The experiment was carried out at the Federal University of Santa Maria-RS, using the following winter cover crops as treatments: Lathyrus (Lathyrus sativus L.); Lupine (Lupinus angustifolius L.); hairy vetch (Vicia sativa L.); black oat (Avena strigosa Schieb) and winter bare soil. Water aggregate stability, organic carbon, microbial activity, soil […]

A new approach is discussed for adoption of criteria in the application of the cultural profile methodology for tropical soil conditions. The evolution of this methodology has been analyzed since its beginning in France in the 1960s, until its proposal for tropical soil management studies. The cultural profile approach can be used to make qualitative diagnosis of the physical state of soil in the field, as well as to help with soil sampling, to study the effect of agricultural machinery, […]

The objective of this work was to evaluate the efficiency of spectral reflectance in the detection of different erosion levels present in soils. Four soils, corresponding to a Red-Yellow Latosol (Oxisol), Latosolic Terra Roxa Estruturada (Ultisol), Cambisol (Inceptisol) and Vertisol, located in a toposequence in Piracicaba, São Paulo, Brazil, were evaluated for their chemical, physical and mineralogical attributes. The spectral reflectance was measured between 400 and 2,500 nm using an Infra Red Intelligent Spectroradiometer. Each soil was collected according to […]

Excessive alkalinity of fertigation waters can create a series of problems such as the blockage of water emitters, carbonate precipitation and the reduction of micronutrient availability for crops. A software, ALKA 1.0, was developed in CLIPPER 5.2, to help manage the alkalinity of those waters. The Program runs in computers IBM-PC/XT/AT/PENTIUM or other 100% compatible. It is initiated with the input of the actual irrigation water pH, its total alkalinity, and the irrigation sheet used during the crop cycle from […]

Carbon storage and its distribution in the profile of clayey Oxisols were studied to evaluate the role of the soil as a sink or source of atmospheric CO2 in the center of the cerrado region, Federal District, Brazil. Evaluations were carried out in six different management systems: a native cerrado type vegetation (CE), eucalypt reforestation (EU), introduced pasture (PA), heavy disk harrow tillage (GP), disk plow tillage (AD), no-tillage (PD), all of them having been established for more than twelve […]

Deactivation of saltworks in Cabo Frio, Rio de Janeiro, has been creating great amounts of organic residues originated from marine algae accumulation. Studies were carried out at the Soil Department of UFRRJ in 1996 to evaluate the potential for using such residues as organic fertilizers. Samples of the residue presented high contents of Ca, Mg, K, Na, S, and elevated values of bulk and real densities, water retention, pH and electrical conductivity; 89% of Na content was found in soluble […]

The Brazilian fertilizer legislation requires that the presence of micronutrients be guaranteed by their total amount. This makes possible to use different products as source of micronutrients for fertilizers, but their agronomic efficiency is still doubtful. The purpose of this work was to characterize the micronutrient solubility and availability of thirty commercial fertilizers through five extractors: water, 2% citric acid, neutral ammonium citrate (1 + 9), 0.005 mol L-1 DTPA and 0.005 mol L-1 EDTA solutions. The results showed low […]

Although widely reported, studies on chemical forms and concentrations of heavy metals in polluted soils and their effects upon ecosystems are still not much emphasized in the tropics. The present study was developed in a waste area of a zinc processing industry owned by the Companhia Mineira de Metais-CMM at Três Marias (MG), Brazil, to evaluate heavy metal quantities and forms in seven representative sites, selected according to differences in form of contamination, pedological aspects, topography and current vegetation status. […]

The main purpose of this work was to evaluate differences in the superficial organic accumulation in soil with regard to some pedological parameters of a secondary forest (older than 40 years) submitted to anthropic intervention, i.e., harvest of economically important tree species. Thus, the present work compares two sites of the “Tabuleiro” Atlantic Forest in northern Espírito Santo: a primary forest, the “Mata Alta”, and a secondary forest, the “Capoeira de Extração”. The organic matter accumulation below the “Mata Alta” […]

The present study was carried out in 1995 to investigate why plants cultivated in a Red-Yellow Podzolic in the State of Acre, in the Brazilian Amazon, presenting high amounts of exchangeable aluminum, have not shown symptoms of toxicity to this element or yield reduction. The exchangeable Al3+ in the B horizon is higher than 14 cmolc dm-3. Samples of the A and B horizons were incubated with increasing rates of lime and subjected to determination of pH in H2O, pH […]