Undisturbed samples of representative horizons of soils from Jaíba Project, northern Minas Gerais, Brazil, and compacted and non-compacted layers of soils under intensive use were collected and micromorphologically analyzed to obtain more information on their evolution degree and also to evaluate the soil alterations caused by agricultural use. Four soils derived from limestone (P1 to P4) and one originated from detritic sediments (P5) were studied, as well as layers with and without indication of compaction. The micromorphological study revelead that […]

The effect of nitrogen levels on the growth and yield of garlic plants grown from tissue culture and conventional propagation. The trial was conducted at an experimental field of the Plant Science Department/UFLA, Lavras, MG, Brazil. A complete randomized block design in a factorial scheme with four replications was used. Plants originated from two propagation methods-tissue culture and conventional and five levels of nitrogen fertilizer – 0, 35, 70, 105 and 140 kg ha-1 were applied during the treatments. Plant […]

The efficiency of surface application of lime under a no-tillage system is doubtful, particularly with regard to subsoil acidity and to methods of lime requirement determination. A field experiment was carried out on a dystrophic Dark Red Latosol (Haplortox) from Ponta Grossa, Paraná, Brazil, from 1993 to 1998, to evaluate the extent of downward movement of lime applied on the surface under a no-tillage system, and the effect on crop rotation grain yields. A randomized complete block design was used, […]

Redox processes affect the reactivity of iron oxides and this can affect the P availability in soils. To evaluate how this processes can affect phosphorus availability, this study was carried out with six Uruguayan soils, which differed in their parent material, and subjected to alternation of the flooded-drained conditions. Soil samples (0-15 cm) of the A horizon, were flooded during 0, 5, 15 and 45 days, drained and sampled after 21 days of air-drying. Fe extracted by ammonium oxalate at […]

The aim of this study was to evaluate the effects of vinasse (100 and 200 m3 ha-1) on the degradation and sorption of diuron in Rhodudalf and Haplorthox soiIs. For the degradation study an experiment was carried out in a completely randomized design with a factorial experiment of 2 (soils) x 3 (vinasse: 0, 100 and 200 m3 ha-1), for 120 days. The mineralization was evaluated by radiorespirometry. At the end of the incubation, the original compounds and their metabolites […]

Sand, silt and clay fraction mineralogy as well as the weathering processes of two soils with excess of sodium (SPL and SS) were studied in the state of Ceará, Brazil. The sand coarse and silt were studied using polarized microscopy and phase contrast, while the fine silt and clay were analyzed by X-ray diffraction. Additional information on the mineralogical transformations that occurred in the horizons of both pedons was obtained using scanning electron microscopy. The Solodic Planosol showed in the […]

Soil Science deals with the understanding and modelling of the phenomena occurring in soils, mainly those related to the non-saturated zone. Since understanding most of those phenomena requires determination of parameters in scales allowing the incorporation of pore and aggregate variability to the models, a microscopic scale X-ray tomograph was built at Embrapa Agriculture Instrumentation. The aim was to generate non-destructive images of soil samples, within at least 100 ∝m spatial resolution. It was possible to design and construct a […]

Attributes of soil, climate and crop management were characterized in ten growing coffee plantations in the western region of São Paulo State. The purpose of this work was to identify the main limiting productivity factors and develop a simple multivariate model to explain observed yield in the period between 1984 and 1989. Over two thousand traits were initially analyzed by simple correlation to the final yield, and the significant ones, with at least 5% level according to the Student test […]

The objective of this work was to investigate the effect of increasing closes of Irati lime on the contents of Cu, Fe, Mn and Zn both in soil and the corn plant. Irati lime is a by product obtained by Petrobras Six during the oil shale mining process, presenting high levels of micronutrients. The experiment was conducted in a greenhouse using pots filled with soil from a “Cambisol Tb” A horizon, of a sandy texture. The treatments were arranged in […]

Based on the seven year-productivities (1989 to 1995) of 36 cacao-producing areas, on a farm in southern of Bahia, Brazil, the average of the three most and least productive years was obtained corresponding, respectively, to the highest and lowest rain availability. By path analysis, these productivities were related to both the soil morphological-physical characteristics (A-horizon depth; color, soil and particle densities of A and B horizons; texture of soil layers at 0-20 and 30-50 cm depth and the presence of […]