963 resultados para NITROGEN MINERALIZATION
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Biomass and forage volume density and the performance and stocking rate of sheep on pastures with nitrogen-fertilized Tifton 85 and subjected to a continuous stocking system were evaluated. Four doses of nitrogen (0, 100, 200, and 400 kg ha-1 year), arranged in an experimental design with randomized blocks and four replications, were analyzed. Sixteen paddocks and Santa Inês sheep were used as test animals, coupled to crossbreed Santa Inês sheep as regulating animal stocking. Nitrogen-fertilized Tifton 85 pastures increased the amount of forage biomass and volume density which affected stocking rate and weight gain of sheep in continuous grazing. When pastures with Tifton 85 were administered in variable load continuous stocking, with grass kept at 15 cm, nitrogen fertilization up to 400 kg ha-1 year is recommended.
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The efficiency of nitrogen fertilization for sod production can be increased by using slow-release sources such as sewage sludge compost, which, due to its characteristics can be a substitute of part or all inorganic fertilization for grass. No results were found for the use of sludge compost in sod production in Brazil. This study evaluated the effect of rates of sewage sludge compost on the production of zoysiagrass. Treatments consisted of five rates of composted sewage sludge compost (0, 12, 24, 36 and 48 Mg ha-1, on a dry basis), plus a treatment of inorganic fertilization (300 kg ha-1 N, 80 kg ha-1 P2O5, and 200 kg ha-1 K2O). The results indicated different mineralization rates of the organic compounds present in the sludge; 120 days after sludge application, more Mg (100 %), K (90 %) and N (67 %) has been released than S (57 %), P (40 %) and Ca (31 %). The use of composted sewage sludge for zoysiagrass adequately supplied nutrients when applied to the soil surface at rates more than 36 Mg ha-1. After sod cutting, the rates of sewage sludge compost provided a linear increase in potential soil acidity, soil contents of OM, P, S, Fe, Cu, Mn, Zn, Cu and Ni, and linear decrease in pH, soil concentration of Ca and Mg and base saturation. Compost rates, increasing from 0 to 48 Mg ha-1, reduced the sod mass, reaching values of 4.0 kg/sod at the highest rate. High compost doses (36 and 48 Mg ha-1, respectively) also induced the highest resistance, with values in the order of 35 and 33 kgf.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The goal of this study was to evaluate the concentrations of non-structural carbohydrate (NSC) and of total nitrogen (N), as well as, to evaluate the root system in Tanzania-grass pastures fertilized with doses of urea in fall, spring and summer. The experiment was conducted at the Experimental Farm of Iguatemi, Maringa, Parana, Brazil, from March 2007 to March 2008. The experimental design was complete random blocks with subplots and four repetitions. The plots showed doses of N (50, 100 e 150 kg ha(-1) of N) plus the control (no N fertilization), and the subplots the season of the year. Root samples were taken at depths of 0-10, 10-20 and 20-40 cm. Root biomass showed a trend for mass accumulation up to a dosage of 100 kg ha(-1) for all seasons evaluated. Also, about 80% of the root system of Tanzaniagrass plants was found on the 0-10 cm layer for all dosages of N. Nitrogen fertilizer above 100 kg ha(-1) may foster fast forage plant growth reducing its NSC root storage capacity although favoring NSC and total N storage at stem base. NSC and total N concentrations were highest in fall, demonstrating that its usage is greater in spring due to the weather conditions being favorable to plant growth. In the regrowth, the largest reserve of total N was at the 0-10 cm root layer and the largest NSC reserve is at stem base.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Nitrogen fertilization (15NH4NO3) of palisadegrass and residual effect on subsequent no-tillage corn
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The biodegradability properties of poly(epsilon-caprolactone) (PCL) and modified adipate-starch (AS) blends, using Edenol-3203 (E) as a starch plasticizer, were investigated in laboratory by burial tests of the samples in previously analyzed agricultural soil. The biodegradation process was carried out using the respirometric test according to ASTM D 5988-96, and the mineralization was followed by both variables such as carbon dioxide evolution and mass loss. The results indicated that the presence of AS-E accelerated the biodegradation rate as expected.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Although many studies have shown that soil solution chemistry can be a reliable indicator of biogeochemical cycling in forest ecosystems, the effects of litter manipulations on the fluxes of dissolved elements in gravitational soil solutions have rarely been investigated. We estimated the fluxes of NH4-N, NO3-N, K, Ca, Mg, Na, Cl, dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) over the first two years after re-planting Eucalyptus trees in the coastal area of Congo. Two treatments were replicated in two blocks after clear-cutting 7-year-old stands: in treatment R, all the litter above the mineral soil was removed before planting, and in a double slash (DS) treatment, the amount of harvest residues was doubled. The soil solutions were sampled down to a depth of 4 m and the water fluxes were estimated using the Hydrus 1D model parameterized from soil moisture measurements in 4 plots. Isotopic and spectroscopic analytical techniques were used to assess the changes in dissolved organic matter (DOM) properties throughout the transfer in the soil. The first year after planting, the fluxes of NH4-N, K, Ca, Mg, Na, Cl and DOC in the topsoil of the DS treatment were 2-5 times higher than in R, which showed that litter was a major source of dissolved nutrients. Nutrient fluxes in gravitational solutions decreased sharply in the second year after planting, irrespective of the soil depth, as a result of intense nutrient uptake by Eucalyptus trees. Losses of dissolved nutrients were noticeably low in these Eucalyptus plantations despite a low cation exchange capacity, a coarse soil texture and large amounts of harvest residues left on-site at the clear cut in the DS treatment. All together, these results clarified the strong effect of litter manipulation observed on eucalypt growth in Congolese sandy soils. DOM fluxes, as well as changes in delta C-13, C:N and aromaticity of DOM throughout the soil profile showed that the organic compounds produced in the litter layer were mainly consumed by microorganisms or retained in the topsoil. Below a depth of 15 cm, most of the DOC and the DON originated from the first 2 cm of the soil and the exchanges between soil solutions and soil organic matter were low. (C) 2014 Elsevier B.V. All rights reserved.