Volume 27, Number 2, 2003

A soil classification system is proposed, based on the aeration and hydration capacities of profiles. Hydration is measured by the available water (field capacity minus wilting point), and aeration evaluated by the connection of available air (total porosity minus field capacity) values and steady state infiltration rate. On this basis, 10 soil orders and 28 soil classes are defined. Input variables are: density of solids, bulk density, porosity, field capacity, wilting point, and steady state infiltration rate. The classification is based on […]

The methodology cesium-137 was used to assess soil erosion and deposition rates in a small watershed with varied crops, at 23º16′ S and 51º17′ W, in a district of Cambé, Paraná State, Brazil. A theoretical equation which considers soil loss or gain directly proportional to the cesium-137 redistribution was utilized in this study. In the watershed, soil redistribution was assessed by transect sampling, and the regional input of cesium-137 by radioactive rainfall determined based on samples from a point in the native […]

Nutrient transport to roots is basically performed by mass flow and diffusion. As the nutrients in the mobile solution (inter-aggregate solution) are depleted, they move by diffusion from the interior to the aggregate surface. This study quantified Mg, Ca, and K in effluents from aggregates of a Brazilian Rodhic Haplustox, in relation to diffusion time, using distilled water as eluate. Treatments were established in a 4 x 5 factorial scheme: four aggregate classes (2.0-1.0, 1.0-0.5, 0.5-0.25, and 0.25-0.105 mm) and five diffusion times […]

The herbicide imazaquin has an acid and a basic ionizable functional group, and its behavior in soil depends on the pH and organic carbon (OC) and oxide contents, mainly in soils with variable charges. The free energy (DG) of 14C-imazaquin molecule sorption was evaluated in surface and subsurface samples of an Anionic “Rhodic” Acrudox (RA), an Anionic “Xanthic” Acrudox (XA), and a Rhodic Kandiudalf (RK), at four different pH levels. The Freundlich equation was fitted to the resulting data to […]

Two field experiments were conducted on two experimental EPAMIG Farms (Minas Gerias State), in order to evaluate the nutritional coffee status by the nutritional balance index (NBI) supplied by DRIS in response to potassium fertilization. The experimental design was a split plot scheme of randomized blocks, carried out on a Red Latosol distroferric (RLdf) of São Sebastião do Paraíso and a Yellow Red Latosol distrofic (YRLd) of Patrocínio. Three K sources were applied in the plots: potassium chloride (KCl), potassium […]

The use of the pH SMP to estimate the potential acidity has advantages in relation to the 0.5 mol L-1, pH 7, calcium acetate method, but it requires previous edaphic regionalization to estimate the H + Al values with safety. In the northwestern region of the State of Paraná there are soils originally developed from sandy sedimentary rock of the Caiuá Formation, called Caiuá Sandstone, of the Cretaceous period. These soils are characterized by low contents of clay and organic matter, and a low buffer capacity, […]

Methods to quantify available silicon (Si) in fertilizers and slags are not yet sufficiently trustworthy. In this study, Si extracted from several sources was analyzed, using the extractors: Na2CO3 + NH4NO3 in varying concentration, time of agitation and of reaction; water; HCl 0,5 mol dm-3; 50 g dm-3 of Na2CO3; 50 g dm-3 of citric acid; 0,5 mol dm-3 of acetic acid; acid cation exchange resin (Amberlite IRC-50, pK 6.1); and the leaching column method. A greenhouse experiment, where 125 kg ha-1 of total Si from 12 different sources was applied […]

There has been an increasing interest to search alternatives for the establishment of crops under no-tillage systems in the southern region of Brazil, opening up new areas without soil disturbance. A field trial was carried out on a dystrophic Clay Rhodic Hapludox in Ponta Grossa, Paraná State, Brazil, from 1998 to 2001, with the aim to evaluate changes in chemical soil characteristics, as well as the soybean response to lime and gypsum applications in a no-tillage system. A completely randomized […]

Calcium silicate slag, as a soil acidity corrective material with long-lasting residual effects, can benefit long-cycle cultures like sugar cane, thus minimizing production drops during the productive cycle. This study evaluated different base saturation levels, comparing calcitic limestone to basic slag as a soil corrective agent, in relation to alterations of some chemical soil properties, as well as to the response of sugar cane rattoon. Sugar cane of the SP 80-1842 type, during the third and fourth cut in the agricultural […]

Sampling soil with the auger hole is simpler and faster than with the cutting shovel. The last is frequently used in no till systems to obtain soil samples for fertility analyses. This study had the following objectives: comparison of two different localized soil sampling systems concerning the horizontal variability of chemical soil characteristics; determination of the necessary unit number to compose a representative sample of the area, and the demonstration that mean fertility values obtained from the composite sample are […]