Álvaro Luiz Mafra

Propriedades físicas e teor de carbono orgânico de um Argissolo Vermelho sob distintos sistemas de uso e manejo

A conservacao do solo e a produtividade das culturas podem ser negativamente afetadas por mudancas causadas a composicao e arranjos dos constituintes do solo por diferentes sistemas de manejo. O objetivo deste estudo foi avaliar a influencia da intensidade de revolvimento sobre atributos fisicos e teor de carbono orgânico (CO) do solo. O experimento foi realizado por 17 anos em Eldorado do Sul (RS), num Argissolo Vermelho de textura media sob diferentes sistemas de manejo: preparo convencional (PC), preparo reduzido (PR) e semeadura direta (SD), utilizando a sucessao de culturas ervilhaca-milho. Uma area de campo nativo (CN), adjacente as parcelas agricolas, foi utilizada como testemunha. As amostras de solo foram coletadas antes do estabelecimento da cultura de verao, nas camadas de 0-2,5, 2,5-7,5, 7,5-12,5 e 12,5-17,5 cm de profundidade. As propriedades avaliadas foram: teor de carbono orgânico, densidade do solo e de particulas, macro, micro e porosidade total, grau de floculacao e estabilidade de agregados. Os sistemas de preparo nao influenciaram a densidade e a porosidade total do solo, mas a distribuicao do tamanho de poros variou conforme a profundidade de amostragem. A macroporosidade foi maior no preparo convencional em relacao ao preparo reduzido e semeadura direta somente na camada de 7,5-12,5 cm, e os microporos foram mais abundantes de 0-2,5 cm na semeadura direta em relacao aos demais sistemas. A adocao da semeadura direta aumentou a estabilidade de agregados da camada superficial do solo em relacao ao preparo convencional, mediante a elevacao no teor de carbono orgânico.

Análise multivariada da fauna edáfica em diferentes sistemas de preparo e cultivo do solo

The objective of this work was to evaluate the effect of different soil tillage and crop management systems on soil fauna groups, by means of multivariate analysis. In the canonical discriminant analysis the conservation soil management systems with crop succession were discriminated in relation to other treatments with crop rotation. The groups Acarina, Hymenoptera, Isopoda, and Collembola, and the Shannon index (H) showed the highest contribution for the discrimination between treatments. The correspondence analysis showed a strong association between Acarina and Hymenoptera groups with the treatment no-tillage with crop succession, and between Collembola group with the conventional tillage system.The objective of this work was to evaluate the effect of different soil tillage and crop management systems on soil fauna groups, by means of multivariate analysis. In the canonical discriminant analysis the conservation soil management systems with crop succession were discriminated in relation to other treatments with crop rotation. The groups Acarina, Hymenoptera, Isopoda, and Collembola, and the Shannon index (H) showed the highest contribution for the discrimination between treatments. The correspondence analysis showed a strong association between Acarina and Hymenoptera groups with the treatment no-tillage with crop succession, and between Collembola group with the conventional tillage system.

Atributos físicos do solo relacionados ao armazenamento de água em um Argissolo Vermelho sob diferentes sistemas de preparo

The tillage systems affect the soil structure, and influence the storage of water available to plants. The objective of the present study was to evaluate the effects of long-term (17 years) of conventional tillage (PC), reduced tillage (PR) and no tillage (SD) on soil physical properties related to water storage in a Loamy Acrisol, in Eldorado do Sul, Rio Grande do Sul State. Soil samples (0-2.5, 2.5-7.5, 7.5-12.5, 12.5-17.5 cm) were collected in a sequence of vetch/corn and in an adjacent native grass field. The soil in SD presented high organic carbon (CO) for the superficial layer and large soil resistance values for depth compared to the conventional tillage. There were no differences among tillage systems of macro and microporosity of the soil, but for PC the saturated hydraulic conductivity increased in depth. No physical restriction to the plant root penetration in the soil under the different tillage systems was verified, which agrees with observation of non-critical observed values of bulk density (1.35 - 1.65 Mg m-3), macroporosity (0.09 - 0.20 m3 m-3) and soil resistance (0.25 - 0.75 MPa). The water retention curves and the available water (AD = 10 kPa (field capacity) - 1.500 kPa (point of permanent wither)) were not influenced by tillage systems, being the low volume of available water (0.05 - 0.09 m3 m-3) related to the texture of this soil. In this case, the increase of the infiltration rate and decrease of water evaporation due to the maintenance of the plant residues on soil surface for reduced tillage and no tillage may contribute to increase availability of water in the initial phase of crop establishment in these systems.

Aplicação de dejeto suíno e estrutura de um latossolo vermelho sob semeadura direta

Objetivou-se, neste trabalho, estimar o efeito da aplicacao de doses crescentes de dejetos suinos, em atributos fisicos do solo. O experimento localizado em Campos Novos, SC, foi conduzido num Latossolo Vermelho Distroferrico, no delineamento experimental em blocos casualizados, com quatro repeticoes, com os tratamentos: testemunha (0); adubo soluvel (AS); combinacao dejeto e adubo soluvel (DS); dejeto liquido suino aplicado nas doses de 50, 100 e 200 m3 ha-1. Desde 2001 foi cultivado milho e aveia preta, sob sistema de semeadura direta. A amostragem do solo foi realizada em janeiro de 2006, nas camadas de 0-5; 5-10; 10-20 cm de profundidade, para determinacao de carbono orgânico, densidade, estabilidade de agregados, macroporos, microporos e porosidade total. A aplicacao de dejeto suino nas doses de 50 e 100 m3 ha-1, reduziu a estabilidade de agregados do solo em relacao a testemunha sem adubacao. Os demais atributos fisicos do solo e o teor de C orgânico nao foram modificados pelos tratamentos, indicando que o uso agricola do dejeto suino, nas condicoes estudadas, mantem a qualidade fisica do solo.

Carbono orgânico e atributos químicos do solo em áreas florestais

The objective of this work was to evaluate organic carbon contents and soil chemical attributes in forest areas in Campo Belo do Sul, Santa Catarina, Brazil, with the following land use: native grassland (NG); 12-year-old loblolly pine (Pinus taeda) reforestation (P12); 20-year-old loblolly pine reforestation (P20); 18-year-old araucaria (Araucaria angustifolia) reforestation (A18); and native forest with araucaria (NF). The soil samples were systematically collected with eight replicates, in the layers of 0.0-0.05; 0.05-0.1; 0.1-0.2 and 0.2-0.4 m. The pinus and araucaria reforestations showed organic C stocks similar to those in native forest and grassland areas, reaching 12.5 to 14.2 kg m-2 in the layer of 0.0-0.4 m depth. Soil acidity and available P contents were highest, in the mean of the analyzed soil layers, under the P20 treatment. Soil nutrient status ranged from low to medium for available P and exchangeable K, Ca and Mg.

Calagem superficial com resíduo alcalino da indústria de papel e celulose em um solo altamente tamponado

Soils of the subtropical highlands of Brazil are nutrient-poor and have high lime requirements, which increases costs and can limit the acidity correction. The objective of this study was to assess chemical and physical modifications of an aluminic Humic Cambissol, and the response of wheat crop to the application of alkaline residue from paper and cellulose industry. The treatments consisted of residue rates corresponding to 25, 50 and 100 % (respectively 2,625, 5,250 and 10,500 kg ha-1) of the recommended liming by the SMP method, to increase pH up to 6.0, in comparison with dolomitic limestone at rates of 50 and 100 % SMP (respectively 5,600 and 11,200 kg ha-1), and the control treatment, with no residue and no lime application, in an experimental design of random blocks with four replicates. The lime was surface-applied in 2004, on a grazed native grassland area, without incorporation. Soil samples were collected from the layers 0-5; 5-10 and 10-15 cm for soil chemical and physical analyses. In 2006, the foliar nutrient contents and grain yield of the wheat crop were evaluated. Surface application of alkaline residue improved soil chemical properties, mainly in the surface layer, and increased soil pH, and Ca and Mg contents. However, the Ca:Mg molar ratio and sodium contents increased, without reaching the critical Na saturation in the soil CEC. Surface liming with residue or limestone linearly decreased the degree of clay flocculation in the surface soil layer. Foliar nutrient contents and grain yield were similar in the liming treatments, with positive response to lime rates.

Pedogênese numa seqüência latossolo-espodossolo na região do alto rio Negro, Amazonas

This paper deals with the genesis of hydromorphic sandy soils with spodosol morphology found in extensive flat surfaces, in which isolated zones with undulating relief emerge, containing well drained oxisols. The objective of this study was to explain the existence of pedogenetic relationship in an oxisol-spodosol system, and to verify the possible development of the sandy materials as a consequence of oxisol transformation. For this purpose, we characterized the morphology of the soils and their physical, chemical and mineralogical attributes. The studied soils showed autochthonous development and filiation to granitic rock of the crystalline basement, displaying lateral genetic relationship between them. Thus, we can admit the occurrence of oxisol transformation, verified in a metric scale, caused by increasing waterlogging conditions. As a result, soil yellowing was found, followed by gleization near the edge of the hill. In this zone, clay depletion was evidenced in the subsuperficial soil layer, extending laterally towards the plain, with the appearance of sandy materials (white sands) near the hill, followed by hydromorphic spodosol. This disposition suggests that evolution of the spodosol occurred after sand formation occurred later. The main pedogeochemical process involved in clay removal would be acidolysis, which causes gibbsite and kaolinite dissolution. Thus, soil transformation would probably have played a preponderant role in the landscape evolution resulting in overall relief planation.

Physical properties and organic carbon content of a Rhodic Kandiudox fertilized with pig slurry and poultry litter

The impact of pig slurry and poultry litter fertilization on soils depends on the conditions of use and the amounts applied. This study evaluated the effect of organic fertilizers after different application periods in different areas on the physical properties and organic carbon contents of a Rhodic Kandiudox, in Concordia, Santa Catarina, in Southern Brazil. The treatments consisted of different land uses and periods of pig and poultry litter fertilization: silage maize (M7 years), silage maize (M20 years), annual ryegrass pasture (P3 years), annual ryegrass pasture (P15 years), perennial pasture (PP20 years), yerba mate tea (Mt20 years), native forest (NF), and native pasture without manure application (P0). The 0-5, 5-10 and 10-20 cm soil layers were sampled and analyzed for total organic carbon, total nitrogen and soil physical properties such as density, porosity, aggregation, degree of flocculation, and penetration resistance. The organic carbon levels in the cultivated areas treated with organic fertilizer were even lower than in native forest soil. The organic fertilizers and studied management systems reduced the flocculation degree of the clay particles, and low macroporosity was observed in some areas. Despite these changes, a good soil physical structure was maintained, e.g., soil density and resistance to penetration were below the critical limits, whereas aggregate stability was high, which is important to reduce water erosion in these areas with rugged terrain in western Santa Catarina, used for pig and poultry farming.

SOIL WATER EROSION UNDER DIFFERENT CULTIVATION SYSTEMS AND DIFFERENT FERTILIZATION RATES AND FORMS OVER 10 YEARS (1)

The action of rain and surface runoff together are the active agents of water erosion, and further influences are the soil type, terrain, soil cover, soil management, and conservation practices. Soil water erosion is low in the no-tillage management system, being influenced by the amount and form of lime and fertilizer application to the soil, among other factors. The aim was to evaluate the effect of the form of liming, the quantity and management of fertilizer application on the soil and water losses by erosion under natural rainfall. The study was carried out between 2003 and 2013 on a Humic Dystrupept soil, with the following treatments: T1 - cultivation with liming and corrective fertilizer incorporated into the soil in the first year, and with 100 % annual maintenance fertilization of P and K; T2 - surface liming and corrective fertilization distributed over five years, and with 75 % annual maintenance fertilization of P and K; T3 - surface liming and corrective fertilization distributed over three years, and with 50 % annual maintenance fertilization of P and K; T4 - surface liming and corrective fertilization distributed over two years, and with 25 % annual maintenance fertilization of P and K; T5 - fallow soil, without liming or fertilization. In the rotation the crops black oat (Avena strigosa ), soybean (Glycine max ), common vetch (Vicia sativa ), maize (Zea mays ), fodder radish (Raphanus sativus ), and black beans (Phaseolus vulgaris ). The split application of lime and mineral fertilizer to the soil surface in a no-tillage system over three and five years, results in better control of soil losses than when split in two years. The increase in the amount of fertilizer applied to the soil surface under no-tillage cultivation increases phytomass production and reduces soil loss by water erosion. Water losses in treatments under no-tillage cultivation were low in all crop cycles, with a similar behavior as soil losses.

Deep subsoiling of a subsurface-compacted typical hapludult under citrus orchard

Soil management practices which increase the root depth penetration of citrus are important to the longevity and yield maintenance of this plant, especially in regions where long periods of drought are common, even in soil conventionally subsoiled to a depth of 30-40 cm, when the orchard was first established. The objective of this study was to evaluate the efficiency of subsoiling on the physical and hydric properties of a Typical Hapludult and fruit yield in a 14-year-old citrus orchard located in Piracicaba, SP. The treatments consisted of: no-subsoiling (with no tilling of the soil after the orchard was planted); subsoiling on one side of the plant lines (SUB. 1); and subsoiling on both sides of the plant lines (SUB. 2). The subsoiling treatments were carried out 1.5 m from the plant lines and to a depth of 0.8 m. Soil samples were taken 120 days after this operation, at four depths, in order to determine physical and hydric properties. Fruit yield was evaluated 150 days after subsoiling. Subsoiling between the plant lines of an old established citrus orchard alters the physical and hydric properties of the soil, which is reflected in increased soil macroporosity and unsaturated hydraulic conductivity, and reduced soil bulk density, critical degree-of-compactness and penetration resistance. The improvements in the physical and hydric properties of the soil were related to an increase in fruit number and orchard yield.