Cláudia Liane Rodrigues de Lima

Grau de compactação, propriedades físicas e rendimento de culturas em Latossolo e Argissolo

The objective of this work was to evaluate soil physical parameters and soybean (Glycine max) and black bean (Phaseolus vulgaris) yields as affected by the degree of compactness of an Oxisol and Alfisol. For the two soils, soil macroporosity, soil penetration resistance (PR), degree of compaction (DC), height and yield of the crops were determined, while for Alfisol saturated hydraulic conductivity (Kqs) was also evaluated. As the DC increases, there is a linear reduction in macroporosity and in Kqs and an increase in PR. Values of DC corresponding to the critical values of macroporosity and PR depend on soil. In the Oxisol, critical values of macroporosity and PR are reached with a smaller DC than in the Alfisol. An intermediate DC in the Oxisol is favorable to the soybean, and the optimum DC for soybean is 86%. To define an optimum DC for soybean and black bean in the Alfisol was not possible due to high levels of soil compaction in this soil.

Estimativa da susceptibilidade à compactação e do suporte de carga do solo com base em propriedades físicas de solos do Rio Grande do Sul

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 in the field was high. Soils with higher initial bulk density were less susceptible to compaction and exhibited less deformation under external loads. With increasing soil penetration resistance, less deformation and greater load support were observed, which does not necessarily indicate a satisfactory soil physical quality for crop cultivation. The greater the soil deformation, the higher is the susceptibility to compaction and the lower is its load support. The compaction susceptibility and load support of a soil can be estimated, respectively, by its initial bulk density and resistance to penetration.

Produtividade de culturas e resistência à penetração de Argissolo Vermelho sob diferentes manejos

The objective of this work was to evaluate the relationship among soybean and bean plant parameters and soil resistance to penetration of an Alfisol under no-tillage and conventional systems. In an experiment deployed under no-tillage in 1989, different wheel tracks of a 10-Mg machine were applied and different soil management systems were used in completely randomized design. Emergence speed index, foliar area index, height and yield of soybean and bean crops and soil resistance to penetration were quantified. The influence of soil resistance to penetration in foliar area index, height and productivity of beans is of 46, 51 and 59% respectively, whereas 55% of the height variation in soybean is explained by soil resistance to penetration. The critical value of soil resistance to penetration indicated for bean and soybean growth and yield is of approximately 1.7 and 1.9 MPa respectively.

Estimativa da capacidade de suporte de carga do solo a partir da avaliação da resistência à penetração

A pressao de preconsolidacao, apesar das dificuldades inerentes a sua obtencao, representa uma medida util do estado mecânico do solo para o seu uso, manejo e planejamento de sistemas de mecanizacao. A estimativa da pressao de preconsolidacao, a partir de propriedades do solo facilmente mensuraveis, e, portanto, uma alternativa que pode ser utilizada para contornar as dificuldades. Os objetivos deste trabalho foram: (a) quantificar a pressao de preconsolidacao e a resistencia do solo a penetracao, em laboratorio e em campo, para um Latossolo Vermelho-Amarelo, sob pomar de laranja, e (b) estabelecer a relacao entre ambos os indicadores fisicos. A amostragem e as avaliacoes foram realizadas em oito dias consecutivos, acompanhando o secamento natural do solo. Houve relacao significativa, positiva e linear entre a pressao de preconsolidacao e a resistencia do solo a penetracao, medida no laboratorio e no campo. A similaridade das relacoes entre resistencia a penetracao, obtida no campo e em laboratorio, e a pressao de preconsolidacao permitiu afirmar que a capacidade de suporte de carga pode ser adequadamente estimada a partir da resistencia de um Latossolo Vermelho-Amarelo distrofico a penetracao medida diretamente no campo.

Densidade crítica ao crescimento de plantas considerando água disponível e resistência à penetração de um Argissolo Vermelho distrófico arênico

Crop establishment is linked to restrictive conditions imposed by soil type and soil management. This study aimed at evaluating the interval of bulk density critical for a Paleudalf, considering water availability to the crops and restrictive values to the root resistance to penetration (1.5; 2.0; 2.5; 3.0 e 3.5MPa). Soil samples, from a Paleudalf under no-tillage since 1989, with preserved structure were collected in the layers of 0.00 to 0.10m and 0.10 to 0.20m depth. The samples (eight replicates) were saturated in water and balanced different potentials (- 0.001; -0.004; -0.006; -0.033; -0.07 and -0.1MPa), plus 2 groups of soil samples were dried in the laboratory for a period of 7 and 9 days, being a total of 128 samples used in this study. After reaching the balance, the soil resistance to penetration and bulk density were evaluated. An increase in the resistance to penetration allows for large intervals of bulk density no restrictive to the plant development. For instance, when considered a resistance to penetration of 2MPa, the adequate interval of bulk density was 1.44Mg m-3 to 1.76Mg m-3, and for a resistance to penetration of 3MPa the interval was 1.53 to 1.88Mg m-3. Bulk density smaller or larger than interval obtained are critical to the development of plants, considering soil resistance to penetration and water availability.

Qualidade físico-hídrica e rendimento de soja (Glycine max L.) e feijão (Phaseolus vulgaris L.) de um Argissolo Vermelho distrófico sob diferentes sistemas de manejo

The physical-hidric quality has been affected by the compaction process that soils are being undergone in different agricultural systems. The objective of this study was to evaluate the physical-hydric quality of a Rhodic Paleudalf undergone to different tillages. One experiment with soybean and two with black bean were installed using a completely randomized experimental design. Seven compaction levels were tested in the agricultural year of 2004/2005: NT= no tillage since 1989; NTPLOW1 = no tillage that received a chisel plough in december of 2004; NTPLOW2 = no tillage that received a chisel plough in december of 2002 and february of 2004; NTCOMP1 = no tillage with four passes of a buck loader of 10Mg in december of the 2001/2002; NTCOMP2 = no tillage with four passes of a buck loader of 10Mg in december of 2002/2003; NTCOMP3 = no tillage with four passes of a buck loader of 10Mg in december of the agricultural year 2001/2002 and 2002/2003 and CT = conventional tillage. The largest changes in the physical-hidric quality were observed in the conventional and no tillage that received additional compaction in two agricultural years (NTCOMP3). No tillage (NT) presented the best physical-hidric conditions of soil and stayed longer within the volumetric moisture range considered ideal for crop development. The hydraulic conductivity of saturated soil did not differ among the treatments. Soybean yield was not affected by the treatments, whereas the chisel plough (NTPLOW1) was favorable to the black bean yield.

ESTABILIDADE DE AGREGADOS DE UM PLANOSSOLO SOB DIFERENTES SISTEMAS DE MANEJO

The wetland soils in the state of Rio Grande do Sul present wide variation in their morphological, physical, chemical and mineralogical characteristics due to the heterogeneity of the parent material and different degrees of hydromorphism. Since their main uses for flooded rice and cattle breeding are frequently low-profit activities, the introduction of dry land crop species in rotation and/or succession with flooded rice has been called for. By broadening the spectrum of wetland soil use, a better weed control for flooded rice and an enhanced physical state of the degraded soil by management systems of reduced soil disturbance would become possible. In this context, the effect of tillage systems on the aggregation state of an Albaqualf has been evaluated: conventional tillage (CT), minimum tillage (MT), no tillage (NT) and pre-germinated (PG), by means of the following attributes: distribution of stable water aggregates in different size classes and mean weight diameter (MWD) of the aggregates. The experiment has been conducted since 1995/96 and is installed in the Estacao Experimental de Terras Baixas (Experimental Station Lowlands-ESL) of Embrapa (Brazilian agricultural research organization), Clima Temperado, district of Capao do Leao (RS). After three years, the NT system favored an aggregate formation of larger sizes, originating largest MWD, while the system PG pushed the largest aggregate concentration of the soil into the smallest size class, with the smallest aggregate MWD. The MWD was lineal and positively correlated with the organic C, not presenting any correlation with the clay dispersed in water.

Compressibilidade de um Argissolo sob plantio direto escarificado e compactado

Soil compressibility depends on the type, intensity and frequency of the load applied by agricultural machinery and on soil management. This study was aimed at evaluating the effect of traffic of agricultural machines on the compressibility of a Paleudalf chisel plough and compacted under no-tillage. In an area under no tillage since 1989, the following treatments were used for sampling: PD = no tillage since 1989; PDE1 = no tillage plus chisel plough in december the year 2002 and february 2004; PDE2 = no tillage plus chisel plough in december 2004; PDC1, PDC2 and PDC3 = no tillage plus four passes of a machine of 10Mg in December, respectively to the agricultural years of 2001/2002, 2002/2003 and 2001/2002 - 2002/2003. Soil cores were collected at 0.08-0.13m depth to evaluate the compressive parameters of soil. In the no tillage under additional compaction higher and lower values were obtained respectively of bulk density and soil compression index. The bulk density and the soil compression index are concistant and sensitive parameters to detect alterations in the soil structure. The non linear model (McNabb & BOERSMA, 1993) is a potential tool to determine the bulk density of soils under no tillage, starting from the initial bulk density and the loads to be applied in the soil.

Fracionamento químico e físico da matéria orgânica de um argissolo vermelho sob diferentes sistemas de uso

The objective of this study was to evaluate the total organic carbon and the physical and chemical fractions of organic matter in an Alfisol under different use systems. The land use systems evaluated was homogeneous forestry of Eucalyptus grandis, agrosilvopastoral system and native grassland, in layers from 0.000-0.025 and 0.025-0.075m depth. The coarse fraction (CFG) and the carbon associated minerals (CAM) were obtained by physical fractionation. The free light fraction (FLL), light occluded (FLO) and heavy (FP) were obtained by densimetric physical fractionation. The non-humicfractions (NH), fulvic acid (AF), humic acid (HA) and humin (HU) were obtained by chemical fractionation. The Eucalyptus grandis system promoted higher total organic carbon, CFG, FLL and FLO and AF. In the surface layer, the protective recalcitrance mechanisms by organic matter molecular and chemical stabilization are overlapping stability which result from aggregates occlusion. As is difficult to form aggregates due to sandy soil matrix, carbon youth which enter the system is decomposed by microorganisms going to a more advanced stage of decomposition, forming in this case associations with silt and clay particles. This occurs in soils where the clay percentage is low. Through the fractionation it was observed that most of the soil organic matter is stored in the form of HU.

Agregação de um planossolo sistematizado há um ano e sob cultivo de arroz irrigado

Land leveling modifies horizontal and vertical soil properties variability. The objective of this work was to evaluate the influence of soil properties (physical and chemical) on aggregation and test the similarity on aggregation of original soil horizons and land leveling. To quantify the intrinsic properties and soil aggregation, disturbed and undisturbed soil samples were collected in two profiles with original characteristics and land leveling areas of an Albaqualf. Aggregation of land leveling was similar to E and B horizons of the original soil. The clay, iron, aluminum and manganese oxides besides the magnesium and exchangeable aluminum were main components that were correlated with soil aggregation Multiple regression analysis revealed positive relationship of the soil aggregation with clay and iron and aluminum oxide crystalline and low crystalline.