In agricultural systems treated with sewage sludge, the management ought to seek an adequate N supply to plants, while avoiding nitrate enrichment because of its potential to pollute subsurface water bodies. Thus, when determining the maximum amounts to be applied to a specific crop, some sewage sludge and soil properties should be known. One is the fraction of organic N of the waste that will be mineralized (NMF) during the crop cycle. This quantity, combined with mineral N in the […]

The available N in sewage sludge-amended soils is one of the restrictive factors for residue application in great amounts. This criterion must be considered in regulations for agricultural use of sewage sludge to avoid environmental pollution of soil and water bodies. The availability of mineral N from native soil organic-N is not considered in the calculation of the maximum rate of sewage sludge application, when these residues are applied for the first time, and this procedure is usual in the […]

Sewage sludge (SS) may be used as a nutrient source in agricultural soils, resulting in environmental and economical benefits, provided that specific technical criteria are applied. Unlike field conditions, residue application rates are estimated based on N mineralization trials under optimum temperature and humidity conditions. The objective of this study was to verify whether it is necessary an addition of mineral N (0, 60 and 120 kg ha-1 N) to sewage-sludge (14 and 16 t ha-1, dry weight) applied to sugarcane ratoon. Sugarcane (RB855536) […]

The amount of silicon accumulated by plants depends on the concentration of available silicon, and this of the soil pH. Silicon absorption and accumulation in grasses is possibly associated with the rhizosphere pH. This study evaluated the effect of rhizosphere pH on Si absorption and accumulation in upland rice (Epagri 109 vr.). The experiment was carried out in a greenhouse in a 5 x 2 factorial design. The five treatments (TR) consisted of a single N dose (200 mg kg-1) […]

Studies about nitrogen and carbon mineralization in soils amended with urban waste compost are important to evaluate the reactions of this waste in soil and to define the best rates for crops. Two experiments were carried out under laboratory conditions to evaluate carbon and nitrogen mineralization in an Ultisol fertilized with urban waste compost. The Ultisol first experiment had a completely randomized design, with five urban waste compost rates of 0, 30, 60, 90, and 120 t ha-1 and three replicates. In […]

Applying lime on the soil surface in soils managed under no-tillage has caused an excess of basic cations in the most superficial layers of the soil profile. On the other hand, subsoil acidity is considered a constraint to the development of deep plant roots. The objective of this study was to evaluate Ca2+, Mg2+, NO3– and SO42- leaching in the soil profile as affected by liming and top dressing nitrogen fertilization in cotton, grown with straw cover on the soil […]

In no-tillage systems lime is applied on the soil surface to avoid soil mobilization. Nitrogen fertilization adds anions that can increase the solubility of basic cations of the soil due to formation of ionic pairs. The objective of this study was to characterize the dynamics of anions (SO42- and NO3–) and cations (NH4+, Ca2+, Mg2+ and K+) in the soil solution, and the nutrient uptake by cotton plants subjected to different lime application forms and ammonium sulfate fertilization, with straw […]

This study aimed to evaluate total N, N-NH4+ and N-NO3– concentrations and pH in columns of alkalinized anaerobic sewage sludge and in percolated liquid, in simulation of real storage conditions. The experiment was conducted in Curitiba – Paraná state, in Cfb climate and rainfall of 197 mm during the incubation period (48 days). The tested factors were: 3 sludge types (covered alkalinized sludge – LCC; uncovered alkalinized sludge – LCD; and uncovered raw sludge – LBD), 4 incubation periods (0; 15; 27; and 48 days) […]

This field experiment was carried out at the Fundação Agrária de Pesquisa Agropecuária [Agrarian Foundation for Agricultural and Cattle Research] (FAPA), in Guarapuava, State of Paraná, Brazil, during the growing seasons of 1999 and 2000. The objective was to verify residual effects of nitrogen fertilization on maize crop under a no tillage system, in presence and absence of white clover and grazing animals. The experimental layout was a completely randomized block design with three replications. The treatments were arranged in […]

The leaching of nitrates and the metals K, Ca, Mg, Cd, Cu, Cr, Ni, Pb and Zn were evaluated in an experiment using biosolids amended soils. The experiment was arranged in a completely randomized block design with four treatments: Typic Hapludox with and without biosolids (LA and LA + sludge) and Rhodic Hapludox with and without biosolids (LV and LV + sludge) and four replications. Biosolids were applied to soils every two months in an average rate corresponding to 78 […]