Phosphorus has low mobility in the soil. Thus, its concentration near the granules of phosphate fertilizers in the soil is very high, which may affect P availability and the soil chemical composition in these regions. This study was carried out to evaluate the soil chemical composition near the granules of calcium or ammonium phosphates and P mobility in two Brazilian acid soils. The experiment was carried out in 2009 and treatments consisted of a combination of triple superphosphate (TSP) or […]

Annual crop yield and nutrition have shown differentiated responses to modifications in soil chemical properties brought about by gypsum application. The aim of this study was to evaluate the effect of gypsum application rates on the chemical properties of a Latossolo Bruno (Clayey Oxisol), as well as on the nutrition and yield of a maize-barley succession under no-till. The experiment was set up in November 2009 in Guarapuava, Parana, Brazil, applying gypsum rates of 0.0, 1.5, 3.0, 4.5, and 6.0 […]

Phosphorus availability in tropical soils may be regulated by the decomposition and mineralization of the labile organic phosphorus fraction (Po); therefore, studies assessing the actual contribution of Po to soil composition are necessary. The objective of this study was to evaluate the total and labile Po content in diagnostic surface horizons of different soil types and to assess which soil properties control the accumulation of these P fractions. Samples of different diagnostic surface horizons were studied, namely histic H and […]

Even following the protocol recommended by the method of analysis, variations in analytical results can be caused by the way samples, or the kind of materials used in the analysis, are handled. The objective of this study was to evaluate the influence of soil particle size, the type of extraction container, and the container void volume on soil P content extracted by Mehlich-1 and Mehlich-3. In the first experiment, soil samples were ground to pass through sieves with 2.000, 1.700, […]

In the search for high efficiency in root studies, computational systems have been developed to analyze digital images. ImageJ and Safira are public-domain systems that may be used for image analysis of washed roots. However, differences in root properties measured using ImageJ and Safira are supposed. This study compared values of root length and surface area obtained with public-domain systems with values obtained by a reference method. Root samples were collected in a banana plantation in an area of a […]

Problems related to leaf retention and lack of uniformity in maturation in the soybean crop have been reported in various regions of Brazil, including the State of Parana, presenting a challenge to Brazilian researchers. Several hypotheses for this problem have been raised in regard to plants nutritional imbalance and intensification of the problem, but no definitive conclusion has been reached. A field experiment was carried out at the Copacol Experimental Farm in Cafelandia, PR, to evaluate how nitrogen availability via […]

The use of potassium (K) rock powder can be an alternative for K supply of crops. Thus, to reduce K fertilizer imports from abroad, possibilities of extracting this nutrient from Brazilian rocks are being studied. The objective was to evaluate the effect of phonolite rock powder (F2) as K source (Ekosil®) on the air-dried fruit yield, nutrition and macronutrient export of Arabica coffee. The experiment was carried out on a dystroferric Red Latosol (Typic Haplorthox), in Piraju, São Paulo State, […]

Pig slurry applied to soil at different rates may affect soil properties and the mobility of chemical compounds within the soil. The purpose of this study was to evaluate the effects of rates of pig slurry application in agricultural areas on soil physical and chemical properties and on the mobility of glyphosate through the soil profile. The study was carried out in the 12th year of an experiment with pig slurry applied at rates of 0 (control), 50, 100 and […]

In recent years, new technologies have been developed to reduce N losses when using urea as a source of this macronutrient. The use of fertilizers with acidic features can reduce ammonia losses from volatilization when combined with urea. The objective of this study was to assess ammonia losses from sources of N with or without coating and/or incorporation of S and bentonite. These fertilizers were applied to the surface of a Haplic Planosol contained in trays (0.1 m2 area and […]

The use of organic residues in the crop fertilizations demand information about the dynamics of decomposition and release of nutrients contained therein. This study aimed to evaluate the decomposition and release of N, P and K from organic residues cattle manure and poultry litter isolates or mixed, using the method of decomposition bags (litterbag) in Alfissol of Coast Tableland in Paraiba State. The experiment was conducted in randomized block with treatments arranged in a factorial 3 × 2 × 5 […]