Spatial variability of infiltration and its relationship to some physical properties

Water infiltration into soil is one of the basic factors for estimating irrigation intensity according to the plants' requirements; this is aimed at avoiding problems of surface run-off and degradation. The purpose of the present investigation was to determine the spatial variation of infiltration and its relationship to some physical properties of soil by means of geostatistical techniques in Typic Plinthaquult soils having average texture and flat relief. A 113 point mesh was designned, having a regular distance of 10 m between points, samples being taken from 0 to 0.20 meters depth. Sand, silt and clay content, bulk density, macroporosity, microporosity and total porosity were determined. Infiltration tests were carried out in the field by means of a 15 cm diameter ring. Descriptive statistics and geostatistics were used for analysing the data. Infiltration, silt and microporosity data did not fit a normal distribution curve. Infiltration had high variability, having an average 36.03 mm h(-1). Total porosity was 56.73%, this being the only property that did not show spatial dependency. The smallest ranges were observed for bulk density, macroporosity and microporosity, having values of less than 40 m. The smallest degrees of spatial dependence were observed for infiltration, silt and clay, evidence also being shown of the influence of silt and clay on infiltration rate. Contour maps were constructed; fitting them to the semivariogram models, together with studying the correlations, led to establishing relationships between the properties.

Time evolution of the structure function and dynamical scaling in porous SnO2 dry gels

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Adubação verde em Citrus: Influência na porosidade e retenção de água de um latossolo vermelho-escuro do noroeste do estado de São Paulo

The objective of this research was to study the porosity, bulk density and retention of water of an Oxisol, located in the Northwestern region of Sn̄o Paulo state, Brazil. The soil was cultivated with Citrus sp., to which green manure was applied between rows for three years. Each of six species of green manure crops (Crotalaria juncea L., Mucuna deeringiana Steph. & Bart., Canavalia ensiformis L. DC., Cajanus cajan L., Lablab purpureum L. and Ricinus communis L.) were seeded for three years (1995, 1996 and 1997) between Citrus rows, plus a treatment with a mix of all six species and a control (natural regrowth af vegetation). The experimental design was a randomized complete block design, with four replications for each of the eight treatments. Water retention, microporosity, macroporosity, total porosity and bulk density were analyzed in the beginning (1995) and end (1997) of the experiment, at three depth ranges (0-0.10; 0.10-0.20 and 0.20-0.40m). We concluded that there were statistically significant differences for bulk density, macroporosity, total porosity and retention of water among the different soil depth ranges; there were no significant differences among treatments though.

Propriedades físicas e infiltração de água de um Latossolo Vermelho Amarelo (Oxisol) do noroeste do estado de São Paulo, Brasil, sob três condições de uso e manejo

This study presents the results obtained in a field experiment carried out at Glicério, Northwest of São Paulo state, Brazil, whose objective was to analyze changes of selected soil physical properties and water infiltration rates on a Yellow-Red Latosol, under three different management conditions. The experimental design was arranged as completely randomized split-block with twelve treatments, which corresponded to four depths (0-0.05 m; 0.05-0.10 m; 0.10-0.20 m and 0.20-0.40 m) and three conditions of soil use and management with four replications. The soil surface conditions were: conventional tillage (one disking with moulboard plus two levelling passes with harrow), nine months before starting filed experiences; recent conventional tillage (also one disking with moulboard plus two levelling passes with harrow) and native forest. The conventional tillage areas were cropped for about fifteen years with annual cultures. The considered soil general physical properties were: macroporosity, microporosity, total porosity, bulk density, soil moisture and penetration resistance and, in addition; soil water infiltration rates were also recorded. According to our results, differences on general soil physical properties and infiltration rates appeared when both tilled sub-treatments and native forest were compared. Both, plots recently prepared by conventional tillage and those prepared by tillage but left nine months in rest, presented a statistically significant decrease of constant (final) water infiltration rates of 92.72% and 91.91% when compared with native forest plots.

Compactação do solo e intervalo hídrico ótimo no crescimento da parte aérea e produtividade da cultura do milho

The aim of this work was to evaluate the effect of soil compaction caused by tractor wheel traffic on the limiting water range (LLWR), shoot growth and levels of compaction and four replications in a completely randomized experimental design. Soil samples with preserved structure were collected in the layers: 0.02-0.05; 0.08-0.11; 0.15-0.18 and 0.22-0.25m to determine macroporosity, microporosity, total porosity, bulk density, resistance to penetration and LLWR. The evaluated corn parameters were: plant and first spike height, steam diameter, number of spikes per plant, plant dry matter, dry matter of 1000 seeds and seed productivity. The soil compaction restricted all corn parameters except the number of spikes per plant and dry matter of 1000 seeds. The LLWR was reduced by the soil resistance to penetration, even in the tilled soil with bulk density of 1.12 Mg m-3. Only the treatment with 11 Mg tractor, repeated four times on the area, demonstrated bulk density above critical bulk density in the LLWR that was 1.37 Mg m-3, where the seed productivity was significantly smaller.

Atributos químicos e físicos de um solo tratado com biossólido industrial e cultivado com milho

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Correlação linear e espacial entre a produtividade e o teor de proteína bruta do guandu anão e os atributos de um Latossolo

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

Atributos físicos do solo em diferentes condições de cobertura vegetal em área de plantio direto

The use of cover crops in the soil causes changes in soil attributes influencing in a series of hydro-physical processes, which also modify the ability of soil to support the many activities that it is intended. Thus, the objective of this study was to evaluate the effect of cover crops on physical attributes of the soil. For this, an experiment was carried out on a Typic Hapludox, Jaboticabal State, Brazil, using cover crops of millet, sunn hemp, jack bean, lab-lab and black velvet bean in no-tillage and fallow area (spontaneous vegetation). The characteristics evaluated were the bulk density, macroporosity, microporosity, total porosity, aggregate stability, penetration resistance and organic matter. The incorporation of cover crops has proved to be a beneficial practice for the physical attributes of the soil, allowing a greater aggregate stability compared to fallow in the depth of 0-0.05 m. All cover crops presented values of soil penetration resistance below the critical value of 2 MPa.

A comparative study of glycerol dehydration catalyzed by micro/mesoporous MFI zeolites

The catalytic properties of monomodal microporous and bimodal micro-mesoporous zeolites were investigated in the gas-phase dehydration of glycerol. The desilication methodology used to produce the mesoporous zeolites minimized diffusion limitations and increased glycerol conversion in the catalytic reaction due to the hierarchical system of secondary pores created in the zeolite crystals. The chemical and structural properties of the catalyst were studied by X-ray diffraction, nitrogen adsorption-desorption isotherms, NH3-TPD and pyridine chemisorption followed by IR-spectroscopy. Although the aim was to desilicate to create mesoporosity in the zeolite crystals, the desilication promoted the formation of extra-framework aluminum species that affected the conversion of glycerol and the products distribution. The results clearly show that the mesoporous zeolites with designed mesopore structure allowed a rapid diffusion and consequently improved the reaction kinetics. However, especial attention must be given to the desilication procedure because the severity of the treatment negatively interfered on the Brønsted and Lewis acid sites relative concentration and, consequently, in the efficiency of the catalysis performed by these materials. On the other hand, during the catalytic reaction, the intracrystalline mesopores allowed carbonaceous compounds to be deposited herein, resulting in less blocked micropores and catalysts with higher long-term stability.

Sistemas de manejo e atributos físico-hídricos de um Latossolo Vermelho cultivado com milho

The purpose of this experiment was to evaluate the hydro-physical attributes of the Red Oxisol cultivated with maize in Jaboticabal, São Paulo State, Brazil, under different systems of use and periods of adoption of managements. The experiment was arranged in a completely randomized design with split-plot arrangement, with six replications and the treatments were: six years of no-tillage system (SPD6), eight years of no-tillage system (SPD8), ten years of no-tillage system (SPD10), conventional tillage system (SPC) and an adjacent area of native forest (NF). The soil penetration resistance (PR), density, macroporosity, microporosity of the soil in layers of 0-0.05; 0.05-0.10 and 0.10-0.20 m, and the saturated hydraulic conductivity (Kθ) in 0.15 m depth were evaluated. It was found that the PR conditions were favorable for the cultivation to 0.20 m, indicating a structure preserved even after soil chiseling. Furthermore, the Kθ in the soil showed similar behavior between SPC and periods of SPD, although this was shown in a part of maize cycle, macroporosity values near 0.10 m3 m-3 and soil water tensions near 0.09 MPa.

Variabilidade espacial de atributos físicos em um cambissolo háplico, sob diferentes usos na região sul do Amazonas

Considering the importance of knowledge of the spatial distribution of soil properties, the purpose of this study was to evaluate the spatial variability of physical properties in a Cambisolunder different land uses in the southern Amazon region. The study was conducted on three farms with cassava, sugarcane, and agroforestry, in the region of Humaitá, in the south of the State of Amazonas. In these areas, 70 x 70 m grids were established, with a regular spacing of 10 x 10 m and a total of 64 points, where soils were sampled at 0.0-0.10 m depth. Texture (sand, silt, and clay), macroporosity, microporosity, total porosity, bulk density, and aggregate stabilitywere determined. The data were analyzed using descriptive statistics and geostatistics. It was found that the propertiesvaried spatially and that the range of these variations between land uses was different, with the highest variability for the sugarcane management.

Variabilidade espacial dos atributos físicos em um Argissolo Vermelho sob floresta

This study aim to evaluate the spatial variability of soil physical attributes in of Alfissol forest in Manicoré region, AM. The mapping of an agroforestry growing area of 70×70m was made using a regular grid sampling of 10 × 10m. In each grid, soil samples were collected at 0.0-0.2 and 0,40-0,60 m depth, with a total of 128 sample points. Physical analyses were made (texture, soil bulk and particles density, macro and microporosity, total porosity and aggregates stability in water). With the exception of DMG, DMP and class aggregates <1.00 mm had all the physical attributes spatial dependence structure ranging from moderate to weak. Values were above the range established in the mesh (12.00 to 45.56 m), enabling to make a basis for future studies in forest area. The physical attributes presented in kriging maps different spatial behavior, however there are relationships between these attributes shown by geostatistics proving that this is effective tool for studies in forest area.

Propriedades físicas de um latossolo vermelho manejado com material orgânico e submetido à compactação

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de resíduos vegetais de milheto (Pennisetum americanum) e da calagem em algumas propriedades físicas de um nitossolo vermelho em sistema de semeadura direta

Pós-graduação em Agronomia (Agricultura) - FCA

Atributos de latossolos e produtividade da cana-de-açúcar em decorrência da diversificação de culturas no período de reforma do canavial

Pós-graduação em Agronomia (Ciência do Solo) - FCAV