Carbon Stocks and Isotopic Composition of the Organic Matter in Soils Covered by Native Vegetation and Pasture in Sorocaba, SP, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soil microbial biomass and organic matter fractions during transition from conventional to organic farming systems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The use of landforms to predict the variability of soil and orange attributes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Soil-lime reactions: the behaviour of a Brazilian red soil.

A red tropical soil was selected, with the main purpose of investigating how it reacted with calcitic and dolomitic limes, and which products are formed. Under normal (23-28oC) or slightly accelerated (40o and 60oC) conditions there is a rapid and substantial interaction between lime (calcitic or dolomitic) and the soil. The reactions take place in two steps, one before 7 g lime/100 g soil, and the other after 8 g lime/100 g of soil, either for calcitic or dolomitic lime. A morphologically discrete reaction product (tri-calcium aluminate hexahydrate) was found in the study, and in spite of the difference in morphology the product is shown to be the same by XRD for all compositions and T.-J.M.H.

Soil humus characteristics in virgin and cleared areas of the paraná river basin in Brazil

A study of the characteristics and distribution of the soil humus fractions in representative ecosystems of central Brazil was carried out with special emphasis on the comparison between the soils under virgin vegetation-Cerrado-and those subjected to cultivation. In spite of the contrasted vegetation and cultural practices in the sites studied, the soil humus showed analogous characteristics: there was a negligible amount of plant residues, the humic and fulvic acids amounted to approximately 70% of the total organic carbon, and about 40% of these humic substances were in extremely stable association with the soil mineral fraction, the HCl-HF treatment being required for their extraction. The stability of such organo-mineral complexes increased slightly in the cultured sites. The study of the humic acid fraction showed increased oxidation and aromaticity in most of the cultivated sites: the lowest values for the IR alkyl vibrations and H/C atomic ratios and the highest ones for the optical density at 465 nm were observed in sites transformed into orchards, whereas the above changes were small in those used as pasture. The 14C NMR spectra confirmed that the proportion of polyalkyl structures decreased in the humic acids of soils subjected to cultivation, as opposed to that of carboxyl groups. In spite of the high stability inferred for the organic matter throughout the wide area examined, the samples from the original Cerrado as well as from those transformed into pastures showed, in laboratory conditions, higher mineralization rates than those from the sites subjected to cultivation. This is partly attributed to the decreased proportions of extractable humic substances in the latter. © 1992.

Solar energy budgets in central Amazonian ecosystems: a comparison between natural forest and bare soil areas

In order to estimate the deforestation consequences on the actual solar energy budget of the Central Amazon Region, two ecosystems of different characteristics were compared. The present conditions of the region were represented by a typical 'terra firme' forest cover located at INPA's Ducke Forest Reserve, where the measurements necessary to evaluate its solar energy balance were carried out. The second ecosystem, simulating a deforested area, was represented by an area about 1.0 ha without natural vegetation and situated in the same Reserve. In this area lysimeters were placed, two of them filled with yellow latosol and two others with quartzose sand soil. Both soils are representative soils in the region. Their water balances were taken into account as well as the other parameters necessary to compute the solar energy balances. The results showed that water loss by evaporation was about 41.8% of the total precipitation in the yellow latosol lysimeters and about 26.4% for the quartzose sand ones. For the forest cover it was estimated an evapotranspiration of 67.9% of the rainfall amount. In relation to solar energy balance calculated for the forest cover, it was found that 83.1% of the total energy incoming to this ecosystem was used by the evapotranspiration process, while the remaining of 16.9% can be taken as sensible heat. For bare soils, 55.1% and 31.8% of the total energy were used as latent heat by yellow latosol and quartzose sand soils, respectively. So, the remaining amounts of 44.9% and 68.2% were related to sensible heat and available to atmospheric air heating of these ecosystems. Such results suggest that a large deforestation of the Amazon Region would have direct consequences on their water and solar radiation balances, with an expected change on the actual climatic conditions of the region. © 1993.

Cumulative effects of vinasse on the characteristics of red-yellow latosols under cerrado vegetation

Vinasse, a liquor effluent from the alcohol and sugar making industry, was applied annually for twelve years to medium-textured red-yellow latosols under cerrado vegetation sensu stricto, to study the environmental impacts on the biotic and abiotic factors. Four plots were established of which two acted as control and the other two received annual doses of vinasse. The studies were begun in 1980 when the first annual dose of 20 L m-2 year-1 was added to the soil without removing the top scrub layer. Theses doses were added to the soil until 1983, but in 1984 the doses were increased to 50 L m-2 year-1 and used until 1991. Soil samples were taken at a depth of 15 cm every three months from 1987 to 1991. Twenty seven environmental variables in the vinasse-treated and untreated plots were studied. These factors consisted of different enzymatic activities, a number of filamentous fungi, bacteria, actinomycetes and other micro-organisms, nutrients and some micro-climatic factors. The results obtained were statistically analyzed using the Tukey test, Pearson correlation and variance test methods with replicates and three factors. Matrices were determined using the correlation coefficient method and were compared with those of earlier published studies in the same area. The comparison of the results helped characterize changes in the environmental factors studied and in the correlation between them, after using annual cumulative doses of vinasse. Positive effects were observed only for the first six years of this application but vinasse had negative effects after the seventh year. It is concluded that medium-textured red-yellow latosols cannot be treated with vinasse for proloned periods.

Interaction in culture medium of acttnomycetes and native fungi wtth rhizobia that form nodules in Neonotonia wighth lackley (perennial soybean)

The relationship between soil fungi and actinomycetes, with rhizobia that produce nodulation in Neonotonia wightii (perennial soybean) was studied in culture medium in order to obtain material to be used in mixed inoculations of this legume. A field experiment was designed to provide soil samples and isolate microorganisms belonging to these groups that are capable of interfering in the development of two selected rhizobium strains. Results show that the Bradyrhizobium strains used in the experiment, which are efficient in nodulation of Neonotonia wightii, are highly sensitive to substances produced in the culture medium by actinomycetes and fungi.

Effect of soil moisture content and the irrigation frequency on the sugarcane germination

The aim of this work was to observe the interaction between soil moisture and irrigation time intervals on the germination of sugarcane cv. RB785148 sets in semi-controlled conditions. One-bud sets of the variety RB785148 were germinated in ceramic pots filled with soil under a transparent PVC cover using soil humidity levels of 22, 25 and 30%, that were restored at intervals of 7, 14 and 21 days. The experiment was carried out at three different periods of the year: May-June/94; Oct.-Nov./94; and Mar.-Apr./95. The results indicate that the germination decreased mainly in function of the decrease in soil humidity, whereas irrigation interval have no statistical effect on germination. An interaction between humidity level and irrigation interval was observed. A variation of the timecourse of the germination could be observed when the results of the experiments installed at different dates were compared.

Recuperação de povoamento de Eucalyptus urophylla com aplicações de nitrogênio, potássio e calcário dolomítico

A plantation of Eucalyptus urophylla, established in 1984 on a Quartzpsamment Soil, at Altinopolis, São Paulo State, presented in 1989 an medium increment of the cylindrical volume of the trees of 13.97 m 3/ha/year and also showed deficiency symptoms of potassium, calcium and magnesium. At 4.33 years after planting were applied two doses of nitrogen (0 and 10 g/tree of N), potassium (0 and 20 g/tree of K 2O) and of dolomitic lime (0 and 500 g/tree), combined in a randomized block design arranged in a factorial way (2 × 2 × 2), with four replications, in order to study the recuperation of the tree growth rate. Evaluations of the trees growth were performed at 4.33, 5.67, 6.75 and at 7.58 years when cutting the plantation was done. The soil fertility and leaf concentrations of N, K, Ca and Mg were analyzed before and after the application of the treatments. The accumulation and distribution of biomass and of these nutrients in the tree components and in the litter, and the economic studies referring to the volumes of wood were also evaluated 7.58 years after planting. Potassium fertilization increased the mass of potassium in stemwood, stembark, foliage, fruits and litter, but the increase was greater in foliage and in the stembark. Liming increased the mass of magnesium in stemwood, stembark, foliage and litter, but the increase was greater in the litter. There was no isolated effect of nitrogen fertilization. The growth rate of trees was recovered with the potassium application, which increased the mean annual increment (MAI) of cylindrical volume from 13.85 m 3/ha/year without fertilizer to 16.82 m 3/ha/year. At 7.58 years after planting, there was observed an effect of the N x K x dolomitic lime interaction in the wood production. In the absence of nitrogen and dolomitic lime, the application of potassium increased the real volume of 43% and there was a gain of US$ 86.79/ha.

Studies on the interaction between humic substances and conducting polymers for sensor application

The interaction between humic substances and poly(o-ethoxyaniline) (POEA), a conducting polymer, was investigated for both solution and self-assembled films. The results have shown that the humic substances induce a doping of POEA by protonation, as indicated by UV-Vis and Raman spectroscopies. The atomic force microscopy (AFM) studies on the self-assembled films have shown that the average roughness of the polymer film has increased after exposing it to humic substances (fulvic and humic acids), consistent with the interaction between POEA and humic substances. However, this change in morphology is reversible by washing the films with water in agreement with the electrical data allowing using this system in sensor applications. Here, the sensor formed by an array of different sensing units was able to detect and distinguish humic substances in aqueous solution, as shown by multivariate analysis (principal component analysis). The motivation to detect humic substance comes due to its importance in terms of quality control of water or soil. ©2005 Sociedade Brasileira de Química.

Spatial and temporal variability in soil CO2-C emissions and relation to soil temperature at King George Island, maritime Antarctica

Few studies have examined the effects of temperature on spatial and temporal trends in soil CO2-C emissions in Antarctica. In this work, we present in situ measurements of CO2-C emissions and assess their relation with soil temperature, using dynamic chambers. We found an exponential relation between CO2 emissions and soil temperature, with the value of Q10 being close to 2.1. Mean emission rates were as low as 0.026 and 0.072 g of CO2-C m-2 h-1 for bare soil and soil covered with moss, respectively, and as high as 0.162 g of CO2-C m-2 h-1 for soil covered with grass, Deschampsia antarctica Desv. (Poaceae). A spatial variability analysis conducted using a 60-point grid, for an area with mosses (Sannionia uncianata) and D. antarctica, yielded a spherical semivariogram model for CO2-C emissions with a range of 1 m. The results suggest that soil temperature is a controlling factor on temporal variations in soil CO2-C emissions, although spatial variations appear to be more strongly related to the distribution of vegetation types. © 2010 Elsevier B.V. and NIPR.

Indicators of soil degradation in urban forests: Physical and chemical parameters

The fragmentation of forest habitats in urban areas has aroused increasing interest in recent years according to the growing environmental problems. The fragmentation of theses ecosystems is caused, in general, by the pressure of housing, agriculture and industry, causing losses in biodiversity and problems of soil degradation in the border areas of theses remnants. The establishment of indicators of soil degradation becomes essential for the implementation of conservation and reclamation. This study analyzes physical and chemical characteristics of soil under different forms of vegetation in the forest surrounding the Quilombo Forest, located in Campinas/SP - Brazil, and examines the possibility of using these indices as indicators of environmental degradation in urban remnants. The parameters analyzed were: specific weight natural (γn), specific weight of solids (γs) Ca, P, K, Mg, pH, organic matter, H + Al, Sum of Base (SB) Percent Base Saturation (V%), Cation Exchange Capacity (CEC). The study shows that in general the different forms of land used in the study area significantly changed (or according to) the physical aspects of soil The porosity and voids of the soil stood out as the best indicators of soil physical degradation in the layer 0-20 cm deep. In relation to chemical indices, the soil under the cultivation of cane sugar had a significantly higher pH, K, Ca, Mg and sum of bases. The areas of forest showed higher levels of phosphorus, organic matter and CEC, indicating the importance of maintaining vegetation and replacement for the cycling of organic matter.

Carbon dioxide emissions under different soil tillage systems in mechanically harvested sugarcane

Soil tillage and other methods of soil management may influence CO 2 emissions because they accelerate the mineralization of organic carbon in the soil. This study aimed to quantify the CO2 emissions under conventional tillage (CT), minimum tillage (MT) and reduced tillage (RT) during the renovation of sugarcane fields in southern Brazil. The experiment was performed on an Oxisol in the sugarcane-planting area with mechanical harvesting. An undisturbed or no-till (NT) plot was left as a control treatment. The CO2 emissions results indicated a significant interaction (p < 0.001) between tillage method and time after tillage. By quantifying the accumulated emissions over the 44 days after soil tillage, we observed that tillage-induced emissions were higher after the CT system than the RT and MT systems, reaching 350.09 g m-2 of CO2 in CT, and 51.7 and 5.5 g m-2 of CO2 in RT and MT respectively. The amount of C lost in the form of CO2 due to soil tillage practices was significant and comparable to the estimated value of potential annual C accumulation resulting from changes in the harvesting system in Brazil from burning of plant residues to the adoption of green cane harvesting. The CO 2 emissions in the CT system could respond to a loss of 80% of the potential soil C accumulated over one year as result of the adoption of mechanized sugarcane harvesting. Meanwhile, soil tillage during the renewal of the sugar plantation using RT and MT methods would result in low impact, with losses of 12% and 2% of the C that could potentially be accumulated during a one year period. © 2013 IOP Publishing Ltd.

Interaction between Linepithema micans (Hymenoptera: Formicidae) and Eurhizococcus brasiliensis (Hemiptera: Margarodidae) in vineyards

Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae) is a soil scale that is considered the main pest of vineyards in Brazil. The ant Linepithema micans (Forel) (Hymenoptera: Formicidae) is frequently found associated with this species of scale in infested areas. The effect of the presence of L. micans on the infestation and dispersal capacity of E. brasiliensis on vine roots was measured in a greenhouse, using Paulsen 1103 rootstock seedlings planted in simple and double Gallotti Cages. Treatments measured were: infestation of roots with E. brasiliensis or L. micans, and infestation with both species together. In the experiment using simple Gallotti Cages, with E. brasiliensis associated with L. micans, higher mean numbers of cysts and ants per plant were recorded, a result significantly different from that found for infestation with scale only. When double Gallotti Cages were used, first-instar nymphs were transported between the cages. The results showed that L. micans transports and aids in the attachment of E. brasiliensis to vine plants. © 2013 Entomological Society of America.