30 results

Respiratory activity of soil microbiota and glucose content in response to phosphorus addition in Cerrado soil- Brazil

Adão de Siqueira Ferreira, Reinaldo Silva de Oliveira, Maria Amelia dos Santos, Elias Nascentes Borges

01/Oct/2008

Metabolic activity of microorganisms is one of the main processes of control on the nutrient transformation in soil. However, the activity of the soil microbiota is affected by various factors such as the available nutrients, including phosphorus. The present work had as objective to show an approach of the effect of phosphorus addition (50 to 500 mg kg-1 P of dry soil) on the respiratory response of soil microbiota and the amount of extra and intracellular glucose in typic acrustox of Cerrado.The […]

Solubilization of Patos de Minas and Arad rock phosphate in two flooded soils

Gustavo Krüger Gonçalves, Rogério Oliveira de Sousa, Ledemar Carlos Vahl, Leandro Bortolon

01/Oct/2008

Differences in grain yield were not observed in experiments with paddy rice when comparing soluble phosphates and rock phosphate as phosphorus sources. However, chemical changes in flooded soils such as increases in pH and phosphorus and calcium levels in the soil solution probably decrease the dissolution of rock phosphates in flooded soils. The current work was therefore carried out with the objective of studying the solubilization of phosphate rocks in flooded soils. Two experiments, conducted in a random block design […]

Organic fertilization of potato with manure and, or, Crotalaria juncea. II – Soil N, P, and K availability throughout the growing season

Tácio Oliveira da Silva, Rômulo Simões Cezar Menezes

01/Feb/2007

Soil fertility levels in the Agreste region, state of Paraíba, Brazil are generally low. Usually, animal manure is applied to soils to supply agricultural crops with nutrients. However, depending on the quality of the manure applied, incorporation can lead to soil nitrogen immobilization in the beginning of the growing season. It was hypothesized that planting and incorporating crotalaria (Crotalaria juncea) together with animal manure could synchronize the nutrient mineralization pattern more specifically with crop demand. In 2003, field and green-house […]

Organic fertilization of potato with manure and, or, Crotalaria juncea. I – Long term plant productivity and soil nutrient stocks

Tácio Oliveira da Silva, Rômulo Simões Cezar Menezes, Holm Tiessen, Everardo Valadares de Sá Barreto Sampaio, Ignácio Hernan Salcedo, Luciano Marcal da Silveira

01/Feb/2007

Potato (Solanum tuberosum L.) is an important cash crop in the semi-arid region of Paraíba, Brazil. However, potato productivity is limited by low soil fertility and the limited and highly variable precipitation pattern of this region. Animal manure is the main nutrient source for soil fertility amelioration, but farm manure available is usually not enough to fertilize crops. A cover crop could decrease the demand for animal manure. The characteristics of Crotalaria (Crotalaria juncea L.) recommend it as green manure. […]

Effect of natural phosphates on melon plants cultivated in pots

Clementino Marcos Batista de Faria, Davi José Silva, José Maria Pinto, Tâmara Claudia de Araújo Gomes

01/Dec/2006

Organic agriculture is an emerging activity in the upper mid São Francisco River Valley, requiring technologies that are in line with the principles of this agricultural system. A study was carried out at Embrapa Semi-Árido to evaluate the efficacy of natural phosphates applied to three regional soils (dystrophic Grey Argisol – PAGd, eutrophic Yellow Argisol – PAe and Vertisol – V) planted with melon (Cucumis melo) in pots accommodated on wooden benches. The factorial treatments (3 x 4) + 1 […]

Phosphate forms in plant and their internal buffering in five soybean cultivars

Hermínia Emília Prieto Martinez, Roberto Ferreira Novais, Luciana Aparecida Rodrigues, Luis Vitor Silva do Sacramento

01/Apr/2005

Differences among plants in their ability to support nutritional stress periods may be caused by a differential vacuole capacity of ion storage and release and may also depend on the intensity of nutrient re-translocation under such conditions. In five soybean cultivars, submitted to eight days of P deprivation, the dry matter production and the contents of three phosphorus (P) forms – inorganic (Pi), organic (Po), and acid-soluble total (Pts) of different plant organs were determined. Pi release velocity (RSPi) was […]

Soil chemical properties and corn production in a sewage sludge-amended soil

M. V. Galdos, I. C. De Maria, O. A. Camargo

01/Jun/2004

The application of sewage sludge into agricultural soils, as organic fertilizer or soil conditioner, is becoming an increasingly more attractive alternative. It is occurring because of the high costs and environmental impacts caused by other sludge disposal methods, besides the presence of plant nutrients and organic matter in the sludge and the need to reduce costs in agriculture. However, sewage sludge can contain heavy metals, pathogenic microorganisms, and toxic organic compounds. In order to study the impact of sewage sludge […]

Decomposition and nutrient release from leaf litter in pure and mixed stands of native tree species in southeastern Bahia State, Brazil

A. C. Gama-Rodrigues, N. F. Barros, M. L. Santos

01/Dec/2003

Leaf litter decay rates and N and P fluxes of tree species are different in pure and mixed stands because the decomposition process is not only defined by the quality of the substrate, but of the microenvironment (forest production systems) also. The objetive of this work was to estimate the decomposition rate and N and P release from leaf litter of native forest species planted under two different systems. Twenty two year-old mixed and pure stands of six hardwood species […]

Addition of organic and humic acids to Latosols and phosphate adsorption effects

F. V. Andrade, E. S. Mendonça, V. H. Alvarez, R. F. Novais

01/Dec/2003

Organic matter can reduce P adsorption/precipitation (PA/P) by: release of organic acids which compete for phosphate adsorption sites; trough the formation of P- compounds in the soil solution; and by building complexes with Fe and Al and thus decreasing PA/P. The aim of this study was to evaluate the PA/P in Oxisols, by addition of organic acids: citric (CA), oxalic (OA), salicylic (SA), and humic acids (HA). An amount of 2.5 cm3 samples of a clayey Red Latosol (Rodic Hapluxtox) and […]

Nitrogen fertilization efficiency with Urea (15N) in Brachiaria brizantha cv. Marandu associated with split application of ordinary superphosphate and potassium chloride

P. P. A. Oliveira, P. C. O. Trivelin, W. S. Oliveira

01/Aug/2003

In pastures, the evaluation of fertilization efficiency of urea-N is important since it is applied on a massive scale. Several studies report an enhancement of the fertilizer’s efficiency by associated applications of urea with potassium chloride (KCl) and ordinary superphosphate (OSP). In the recovery of degraded pastures or in intensive exploration systems, high quantities of KCl and OSP used as corrective fertilization are applied at the november, beginning of the rain season. Split applications of KCl and OSP could easily […]

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