Physical, chemical and mineralogical characteristics of soils from the meadows of Sousa (Paraíba State – Brazil) were studied, as well as the effect of alkaline and alkaline-earthy cations on humic substance stability. Furthermore, criteria of environmental distinction used by the small farmers and different forms of land use in the studied region were identified. Profiles from the classes Ustifluvents (Neossolo Flúvico), Haplustalfs (Luvissolo), Natrustalfs (Planossolo nátrico), and Usterts (Vertissolo crómico) were therefore selected, sampled and analyzed. Besides sodium, magnesium also […]

In Brazilian legislation, the control for micronutrient concentrations in mineral fertilizers considers the total content. As a consequence, low-cost by-products and even industrial residues are generally used as a source for micronutrients, despite their low availability to plants. To evaluate fertilizer solubilities, water, citric acid 20 g L-1, and neutral ammonium citrate (1 + 9) extracting solutions were applied to mixtures containing micronutrients. The same study was realized for micronutrient sources. Results were similar for both sources and mixtures. Citric acid solution 20 g L-1 was […]

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 […]

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 […]

Aluminum tolerant wheat varieties can present increased efficiency of phosphorus use in presence of aluminum. A greenhouse experiment was conducted in 1994 to compare the wheat cultivars (Toropi) and (CNT 8), considered efficient and inefficient, respectively, in relation to phosphorus use. Nutrient solutions containing two phosphorus (1.6 and 32.3 µmol L-1) and two aluminum (0.0 and 37.0 µmol L-1) concentrations were tested. Root morphology and phosphate use were established for the plants, which were harvested from the pots on the 31th day. Roots of the Toropi […]

The use of the Universal Soil Loss Equation to predict erosion losses and for conservation planning requires an evaluation of index values of local rainfall erosivity. As a contribution to knowledge on these indexes in the coastal zone of Ceará State, the objectives of this study were: (a) to determine the R factor and the annual EI30 index values, its monthly distribution, probability of occurrence and return periods in Fortaleza, Ceará State, Brazil for the period of 1962 to 1981, […]

An increase in the use of winter mixed cover crops has been observed in Southern Brazil during the last years. As a new agricultural practice, it is important to evaluate its potential benefits in dry matter production and nutrient accumulation. A field experiment was carried out from 1998 to 2000, in UFSM (RS), on a Typic Paludalf soil. Black oat (Avena strigosa Schieb) + common vetch (Vicia sativa L.) and black oat + oilseed radish (Raphanus sativus L. var. oleiferus […]

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 […]

The correlation between the erosivity index EI30 and the rainfall coefficient (Rc) for the period of 1962 to 1981, in Fortaleza (CE), was evaluated to analyze the feasibility of the Rc use to update erosivity values from 1982 to 2000 in this county. An equation that could be used to estimate erosivity in other locations of the coastal region of Ceará State, where there are no rain gauge charts available, was a second aim. A high correlation coefficient (r = […]

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 […]