EVOLUTION PATTERNS OF THE SOIL ORGANIC-MATTER IN SOME AGRICULTURAL SYSTEMS IN THE BRAZILIAN CERRADO REGION

Several changes in the soil humus characteristics were observed after clearing the Central Brazil virgin forest. When compared with the original ''Cerrado'' forest, the soils from the agricultural systems showed increased values for cation exchange capacity, total organic matter and non-extractable humin. The humic acid fraction underwent some changes suggesting increased oxidation and decreased aliphatic content. The soil organic N tends to accumulate in the insoluble humus fractions.The above changes were much less intense when the virgin forest was transformed into pastures. Under these conditions, the most significant changes were the reduction of readily biodegradable soil organic matter fractions.In view of the intensity of the lixiviation processes in the area studied, the above changes may be connected with the reduction in aggregate stability observed in the cleared sites.In general, the characteristics of the humus formations in the ''Cerrado'' region suggested high resistance to external factors, which is in part attributed to the active insolubilization of humic colloids by the Al and Fe oxides. In the absence of erosive processes in the cleared sites, additional humus stability may conform both to selective biodegradation and/or lixiviation of the humic colloids, or to the effects of the fire used in soil management.

Alterações na produtividade e composição nutricional de uma pastagem após segundo ano de aplicação de diferentes doses de cama de frango

The objective was to evaluate the potential use of poultry litter, compared to mineral fertilization, productivity, features bromatologic and absorption of nutrients from a pasture of Brachiaria decumbens. The experimental area was installed in oxisoil in Uberlandia-MG. The design was randomized blocks with four replicates and the treatments used: control (without application of organic or mineral source), mineral fertilizer (60, 75 and 100 kg ha(-1), P K, respectively); organic fertilization with poultry litter at rates of 3,125, 6,250, 9,375 and 12,500 kg ha(-1). There were two cuts of the aerial part of Brachiaria decumbens, both at 60 days after treatment. We evaluated the yield of DM and the levels of CP, NDF, ADF, lignin, macro and micronutrients in shoots of grass. The results showed that application of poultry litter increased the productivity of DM and the levels of CP, N, P, K and Zn in Brachiaria decumbens. The poultry litter can be used as supplementary source of nutrients, the mineral fertilizer. The use of poultry litter not increased over the levels of S, Ca and Mg in Brachiaria decumbens.

Variabilidade espacial da textura de um argissolo vermelho amarelo sob cultivo de pastagem e vegetação nativa

The study of the spatial variability of soil attributes under different crop helps the study of changes due the management. This research was carried out to determine spatial variability the particle-size distribution, using of the classic statistic and geostatistics, of a soil cultivated with pasture and native vegetation. Soil samples were collected in the layer 0-0.20m, at the crossing points of a regular grid with 10m-intervals, summing up 64 samples points in each area. In the pasture area the fractions of coarse and total sand presented larger mean values in relation to the native vegetation, and negative correlation with the altitude of the points samples in the two areas. All of the fractions presented moderate to high spatial dependence in the two areas and with the defined still, with exception of the fine sand and the silt in the pasture. Much of this variability occurs as a function of water erosion.

Tillage and phosphorus management effects on enzyme-labile bioactive phosphorus availability in Cerrado Oxisols

Phosphorus (P) is an essential element in crop nutrition, which can be growth limiting or an environmental contaminant, if present in excess. Tillage practices have a direct effect on the behavior and availability of soil P. Sorption and availability of various P forms were evaluated in an incubation-fractionation study of three soils, a Typic Paleudults (CR soil) and two Cerrado Oxisols (Latossolo Vermelho-Amarelo [LVA] and Latossolo Vermelho [LV]) with distinct biogeochemical characteristics and tillage management history. Phosphate and myo-inositol hexakisphosphate (mIPH) were strongly sorbed by the soils. Maximum adsorption capacities (S(max)) were 2.2-6.9, 3.3-7.8, and 1.6-19.8 mmol kg(-1) for phosphate in the 0-40 cm depths of the CR, LV, and LVA soils, respectively. For mIPH, S. were 1.2-3.7, 3.7-5.5, and 4.6-5.2 mmol kg(-1). Saturation indices reflected the long-term effect of repeated manure applications on the Paleudults and the near saturation of its P holding capacity, in contrast to the recently cultivated Cerrado soils. Tillage method appeared to have altered P retention characteristics of the near-surface zone very slightly, while increases in ligand-exchangeable (EEP;) and enzyme-labile organic P (EDTA-PHP) forms were observed in no-till Oxisols. In the Paleudults, added manure P increased bioactive P fractions and P saturation of no-till near-surface soil zone. Estimates of all bioactive P fractions using the ligand-based enzymatic assay showed it to be an effective method for assessing P availability in soil and developing sustainable P management strategies, particularly in Cerrado Oxisols that were low in organic matter while having an extensive P-fixing capacity. Published by Elsevier B.V.

Sistemas agroflorestais e seus efeitos sobre os atributos químicos em Argissolo Vermelho-Amarelo do Cerrado piauiense

This study aimed to quantify the effects of agroforestry systems (AFS), with different periods of adoption, and slash and burn agriculture (SB) on the chemical attributes of an Ultisol in the 'Cerrado' of Piaui State, Brazil. In two distinct climatic seasons (dry and rainy) four systems were studied: AFS with six (AFS6) and thirteen years (AFS13) of adoption, an area under SB and a native forest (NF), as a reference. In the AFS, in all depths, higher reduction in the Al3+ and H+ + Al3+ contents were observed as well as an increase of pH value and contents of nutrients (N, P, Ca, Mg and K) and organic carbon in soil. In the soil under SB, only in superficial layers, the ash deposited on the soil caused an increase in contents of nutrients, except for P, which was higher in all the depths. There was significant seasonal effect in the contents of nutrients, reducing in the rainy season. Agroforestry systems promoted increase in the nutrient contents of an Ultisol and can be considered useful to improve soil chemical quality in areas of 'Cerrado' of Piau State, Brazil.

Adubação nitrogenada e idade de corte na produção de matéria seca do capim-elefante no Cerrado

The objective of this study was to investigate the effect of the application of N fertilizer and the cutting age on the dry biomass production of elephant grass. The experiment was performed with the variety Paraiso and planted in a Ferralsol in 2008 in the district of Gurupi (State of Tocantins). Four different rates of urea application were tested (0, 50, 100 and 150 kg ha(-1)) and harvests were made at 120, 150 or 180 days after germination (DAG) of the setts. The dry matter and total N accumulation were evaluated. Dry matter production increased with dose of N, the greatest effect being observed at 180 DAG. There was a linear increase in dry matter (R-2 = 0.75**) and N accumulation (R-2 = 0.96**) permitting a productivity of 34 t ha(-1) of dry matter and an accumulation of 471 kg N ha(-1). The N utilization efficiency (biomass production per unit of applied N) increased with plant age. The higher efficiency of N use favored the quality of biomass production for energy production owing to the higher fibre content.

Variabilidade espacial de atributos químicos em um Argissolo sob pastagem

Studies show the importance of knowing the variability of soil attributes for a more efficient management. This work was carried out to evaluate the spatial variability of the chemical attributes of an Ultisol, cultivated with Brachiaria decumbens pasture in Alegre - ES. Soil samples were collected at a depth of 00-0.2 m, at the crossing points of a regular grid with 10 m-intervals, comprising a total of 64 points. Data were submitted to descriptive statistics, geostatistics and kriging interpolation analysis. The coefficient of variation was low for pH, high for Al and m%, and medium the other attributes. The attributes pH, P, H+Al and m% presented strong dependence, and the other moderate dependence. The attributes presented a spatial dependence structure, allowing their mapping by geostatistics techniques.

The reproductive biology of Cybistax antisyphilitica (Bignoniaceae), a characteristic tree of the South American savannah-like "Cerrado" vegetation

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

Cytotoxicity of Active Ingredients Extracted from Plants of the Brazilian "Cerrado"

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

Ticks (Acari: Ixodidae) within various phytophysiognomies of a Cerrado reserve in UberlA cent ndia, Minas Gerais, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Distribuição de poros e densidade de latossolos submetidos a diferentes sistemas de uso e manejo

Man cultivates the soil for centuries, but the intensive business and use of the soils under Cerrado vegetation for agricultural production grew out of the seventies. The objective of this study was to evaluate soil physical characteristics as a function of sampling time and the soil uses in a Cerrado area in Uberlandia City - MG, Brazil. The managements were adopted: degraded pasture (M-1), conventional tillage (M-2), minimum tillage (M-3), tillage absence (M-4), no-tillage (NT) for three years (M-5); NT for nine years (M-6), NT for three years after Pinus (M-7), PD for one year after Pinus (M-8) and Pinus forest (M-9) with 25 years old. The evaluations were conducted in 2002/03 growing season, in two areas. The soils were: area 1, an Oxisol (Red Latosol - LV-1, M-1 through M-5) and area 2, two Oxisols (Red Latosol and Red-Yellow Latosol - LVA and LV-2, M-6 through M-9). The physical attributes studied changed depending of the soil class, sampling time and management systems, with emphasis on the area 2 soils, which, in general, better preserved its main physical attributes. Managements with intense tillage, such as the M-2, are the most soil physically degrade, presenting mostly negative changes to soil bulk density, total porosity, microporosity and macroporosity. Since the systems which promote less tillage, in short term, to preserve desirable physical attributes. The M-9 system had the lowest attributes range, compared to the others.

Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Associação micorízica em espécies arbóreas, atividade microbiana e fertilidade do solo em áreas degradadas de cerrado

The recuperation of areas used during the construction of the hydroelectric plant, especially in 'borrowed areas', is a difficult and long process since all vegetation and the fertile layer of soil were removed. Interventions in these degraded areas could accelerate the revegetation process. The objective of this research was to evaluate the association of arbuscular mycorrhizal fungi (AMF) in tree species, microbial activity (basal respiration) and fertility of 'cerrado' degraded areas. Soil from two areas, pasture soil and exposed subsoil, were utilized. Organic and mineral fertilization, and liming, were added to the pit for better seedlings' initial growth, where 50 mL of preserved cerrado soil was applied as inoculum of microorganisms. Seedlings of 11 tree species were planted: Anadenanthera falcata (Benth.) Speg ('angico-preto'), Acacia polyphylla D. C. ('monjoleiro'), Stryphnodendron adstringens (Mart.) Coville ('barbatimao'), Dimorphandra mollis Benth ('faveiro'), Hymenaea stigonocarpa Mart. ex Hayne ('jatoba-de-cerrado'), Dipteryx alata Vog. ('baru'), Machaerium acutifolium Vogel ('jacaranda-do-campo'), Schinus terebinthifolia Raddi ('aroeirapimenteira'), Magonia pubescens St. Hil. ('tingui'), Lafoensia pacari St. Hil. ('dedaleira') and Tabebuia aurea (Manso) Benth. & Hook ('ipe-amarelo'). Twelve months later, root samples were colleted at the depth of 0-0.10 m and used for evaluations. The subsoil, as compared to pasture soil, was poor in organic matter and presented less microbial activity. The highest mycorrhizal colonization was seen in the species Acacia polyphylla D. C. (monjoleiro), Magonia pubescens St. Hil. (tingui), Hymenaea stigonocarpa Mart. ex Hayne (jatoba-de-cerrado) and Schinus terebinthifolia Raddi (aroeira-pimenteira). These species could be indicated in revegetation projects in 'cerrado' degraded areas. Plants from both areas showed seedlings form high mycorrhizal colonization and low numbers of spores.

Spider assemblages in widely-separated patches of cerrado in São Paulo State, Brazil.

Brazilian cerrado is a biologically-rich, poorly understood, yet rapidly disappearing habitat. Composition of the spider assemblages from areas of cerrado from three separate sites in the State of São Paulo, Brazil were sampled by beating the canopies and adjacent shrubs of three Myrcia (Myrtaceae; "myrtle") tree species. These produced a total of 859 spiders 'belonging to 21 families and 75 species. The most undisturbed and densest cerrado habitat had the largest number and greatest diversity of spider species, encompassing stalkers, ambushers, space web-weavers, and foliage runners. The other two areas were dominated by foliage runners. Spider distribution in this natural and complex habitat was evaluated by classifying the samples into 12 habitat/microhabitat groups according to local of the patch, tree species, and microhabitat (target tree or adjacent shrub). Correspondence analysis was used for ordination of species and groups based on their abundance. Environmental factors such as patches type (p=0.027) and plant species (p=0.046) had significant effects in explaining the ordination. Canonical correspondence analysis was applied for relating the patterns in species richness and/or abundance to the significant environmental factors. A comparison of the results showed that the family composition among the patches is rather similar, and there is a tendency of spiders species overlap an interregional level (patches effect, p=0.027). However, the most similar spider assemblages living on woody vegetation occurred in Myrcia venulosa and Myrcia guianensis at São Carlos and Pirassununga, demonstrating an interregional similarity (plant species effect, p=0.046) that indicates an association between spiders and particular vegetation.

Effects of cumulative doses of vinasse on soil microorganisms in cerrado

Counts of colony forming units of actinomycetes, bacteria and filamentous fungi were determined in cerrado soil treated with vinasse (processed sugar cane effluent) for 5 yr, using doses of 20 l m-2a-1 and 50 l m-2a-1. A temporary increase in the counts of actinomycetes and bacteria for some months after the addition of vinasse was observed. An increased number of fungi was detected throughout the experiment together with qualitative changes in the population. The most abundant fungi in cerrado soil not treated with vinasse (control soil) were Chaetomium, yeasts, Mucor, Penicillium and Trichoderma, while in vinasse treated soils, the same genera adding Verticillium, with the exception of yeasts, were the most common fungi. -Author