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This article aims to highlight the geotechnical, physical, mineralogical, and porosimetric characteristics and their variabilities along a clayey soil profile resulting from basalt under tropical conditions, which may influence soil parameters that are valuable in the development of geotechnical projects and construction control. The samples, obtained through Standard Penetration Test (SPT) drilling and excavation of a well, underwent geotechnical and physical characterization tests, X-ray diffraction (XRD) mineralogy analysis, and mercury intrusion porosimetry. In the uppermost part of the profile, the predominance of macropores generated by the micro-aggregated clay structure may explain the observed mechanical and hydraulic behavior and justify the values of geotechnical parameters, which may not always align with those expected for fine-grained soils. [ABSTRACT FROM AUTHOR]

The species of the genus Urochloa has been highlighted in the crop-livestock integration and practices such as the type of seed used, and the depth of sowing are fundamental for the establishment and production of the pasture. The objective of this research was to evaluate the emergence and growth of plants of Urochloa brizantha cv. Marandu, originating from seeds incrusted or not, sown in different depths and soils. The experimental design was a randomized block design with four replications. The treatments were arranged in a 2x5 factorial scheme, composed of two types of seeds (incrusted or not) seeded in five depths (0; 1; 2.5; 5; 10cm) in medium textured and clayey soils. Plants of U. brizantha from seeds incrusted and cultivated in medium textured soil presented higher emergence, but lower growth in relation to the plants coming from non-incrusted seeds. In soils of clayey texture, the use of incrusted seeds promoted a greater speed of emergency, but less growth of the plants. The sowing of U. brizantha at 1.0 and 2.5 cm depth provided a higher emergence speed, regardless of soil texture and type of seed. After forage cutting, the greatest tillering of regrowth was observed in plants from non-encrusted seeds and sown in soil up to 2.5 cm deep. At regrowth, there was no effect of treatments on forage yield. [ABSTRACT FROM AUTHOR]

The use of pre-emergent herbicides with prolonged residual effect on the soilis one of the factors that provide great efficiency in the control of the weeds. This study objected to evaluate the residual activity of the formulated mixture diuron + hexazinone + sulfometuron-methyl in different doses in soils of sandy and clayey textures. Two experiments were realized out, one for each soil, adopting the factorial scheme 2 x 8 + 1 with three repetitions. Two doses (0.605 + 0.170 + 0.014 and 1.072.07 + 0.302 + 0.025 kg ha-1 of diuron + hexazinone + respectively) at eight times (0, 20, 40, 60, 80, 100, 120 and 140 days, between the application of the formulated mixture and the bioindicator sowing) and another control without application. At 20 and 40 days after sowing of the bioindicator Cucumis sativus, phytotoxification was carried out. Using the non-linear log-logistic model, the t1/2 of the formulated mixture was determined for the two soils studied. In the soil of clay texture, t1/2 of 101 days was obtained, while for the sandy soil the t1/2 of the formulated mixture was of 52 days, for both doses. The prolonged residual effect on clayey soils may be an essential tool in the management of weeds in sugarcane. However, in sandy soils, smaller doses should be used because of the lower residual effect of the mixture and, consequently, avoid environmental contamination. [ABSTRACT FROM AUTHOR]

The municipality of Brejão has special conditions with cooler and rainy weather and deeper soils and well structured, with occurrence horizon latosols with the humic. So the aim of this study was to investigate the changes in chemical, physical and water attributes of the surface horizon of a humic Oxisol subjected to different forms of use in the South Agreste Pernambuco, and investigate the repellency of the soil water. The disturbed and undisturbed samples were collected in a native forest (MN), pasture 5 years (PA5) and grazing 30 (PA30) in three layers 0 to 10 cm, 10 to 20 cm and 20 to 30 cm and evaluated the chemical, physical and water attributes, and realized an infiltration test with simple ring. Chemical attributes presented typicality dystrophic yellow latosols, and attributes related to the acidity showing significant results mainly in the surface layer. Have the physical attributes that most change with inadequate management are the bulk density (Ds) and porosity. For the infiltration test it is clear the presence of soil water repellency. [ABSTRACT FROM AUTHOR]

The use of herbicides with controlled release formulations may constitute important tool to reduce leaching problems and increase the efficacy of atrazine in soil. The aim of this study was to compare the efficiency of control of Urochloa plantaginea (UROPL) and corn grain yield from a commercial formulation (WG) of atrazine and a conlrolled-release formulation (xerogel). The design was randomized blocks in split plots with four replications in a scheme (2x7)+1. Factor A consisted of the formulations of atrazine (WG and xerogel), factor B concentrations of herbicide (0, 2400, 3200, 3600, 4200, 5400 and 8000ha atrazine g-1). Variables assessed consisted of control levels, plant density of UROPL and corn grain yield. The increasing levels of atrazine resulted in increased levels of control UROPL. In assessments made at 28 and 35 days after application, atrazine xerogel showed higher agronomic efficiency than the WG formulation. There were no differences in corn grain yield from plots treated with different formulations and atrazine levels. [ABSTRACT FROM AUTHOR]

Studies of the adsorption of heavy metals in soil can be used to assess this contribution in the contamination of surface and groundwater. This work had as objective to study the adequacy of the models of Langmuir and Freundlich to describe the adsorption of copper in a Rhodic Hapludox soil with clay texture. To determine the adsorption capacity of copper in the soil, we used 2.000 g of soil added 10 mL of CaCl2 0.01 mol L-1 and 10 mL solutions of CuCl2 with different concentrations. The maximum adsorption capacity of copper in the soil, determined by the Langmuir model, was 2.95 mg g-1. Moreover, the results showed that the Freundlich model showed better fit to the experimental data, adequately simulate the adsorption of copper in the soil under study. [ABSTRACT FROM AUTHOR]

The objective of this research was studied theories used specially to simulate real field situations contrasted by empiric data obtained in real real working conditions in mechanized agricultural clay soil with the results obtained in similar studies conducted in other countries. We tried to the graphical representation of the demand required traction force and slippage through the use of Prediction software version 1.0, contrasted with results obtained by applying the theories of prediction Cn, Bn and Mn. Predictive theories Cn, Bn and Mn have good correlation with experimental values, however, there is an overestimation by the theory compared to the values measured experimentally, for traction force and slippage, causing a tractor design inadequate. [ABSTRACT FROM AUTHOR]

The determination of moisture content in soils under tension follows the assumption that the water matric potential is at equilibrium with an applied tension. The time the soil water tension reaches the equilibrium under the 6kPa tension was determined in Hapludalf and Hapludox clay soils. In the Hapludalf, the equilibrium between the applied tension and water matric potential, in most of the samples, was obtained between 72 and 96h, while in Hapludox, equilibrium was not reached until the 168h. The water tension in the samples had no significant correlation with bulk density and did not reach the tension applied on the suction table and sand suction column. Nevertheless, more than 97% of the soil water was extracted at 48h both in Hapludalf and Hapludox, suggesting that this time is sufficient to estimate the soil moisture at 6kPa tension, independently of clay content. [ABSTRACT FROM AUTHOR]