Browsing by Author "Madeira, Manuel"
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- Comportamento do fósforo em solos argiluviados da Região do Alentejo: sorção de fosfatoPublication . Monteiro, M.C.H.; Monteiro, Fernando; Madeira, ManuelO poster apresenta os resultaos de um estudo sobre o comportamento do fósforo em solos argiluviados da Região do Alentejo.
- Crop use and profile distribution of phosphorus in soils that developed on mafic rocks in southern PortugalPublication . Monteiro, M.C.H.; Monteiro, Fernando; Madeira, Manuel; Torrent, J.The phytoavailability of soil phosphorus (P) depends on the different forms in which it occurs and how these forms change after the application of P fertiliser to the soil. Forms of P in the A, B and C horizons of eleven pedons that developed on mafic rocks were characterised by a fractionation method before and after fertilisation with single superphosphate, and a micropot experiment was conducted to assess the shortterm use of P fertiliser by rye (Secale cereale L.). The main sources of P to the crop were (i) phosphate adsorbed on mineral surfaces and pedogenic Fe, Al or Ca phosphates in the A horizon and (ii) Ca-phosphates in B and C horizons. In the C horizons, poor in Fe/Al phases and clay, the precipitated Ca-P showed low solubility, resulting in a reduction in shot biomass. The apparent P recovery by rye was similar in the A (36%) and B (29%) but decreased in the C (15%) horizons. The partial factor productivity (g g−1) decreased from the A (58) to B (11) and C (5) horizons. P phytoavailability decreased with increasing profile depth because the transformation of P fertiliser to poorly soluble Ca-P forms increased with depth.
- Effects of biochar on available P fractions, soil properties and P uptake by plant in P fertilized Ferralsols from AngolaPublication . Auxtero, E.; Madeira, Manuel; Monteiro, M.C.H.Low phosphate (P) availability is one of the major problems in most Ferralsols from Angola, due to the strong ability of these soils to adsorb P, thereby limiting its bioavailability for crop production (Ucuassapi, 2006). Application of biochar as soil amendment, along with superphosphate and rock phosphate fertilizers may be useful in increasing supply of available P. However, appropriate P management strategies may require information on the fate of biochar and applied P fertilizers in the soil as well as on their interaction with soil colloidal constituents. Therefore, information on soil P availability using different methods, and P forms (inorganic and organic) by Hedley modified fractionation procedure (Tiessen and Moir, 1993), early plant growth performance and P content in plant after biochar amendment along with different rates of P fertilizers, is crucial for making appropriate fertilizer and biochar recommendations for crops.
- Extractability of P in major soils of Angola as affected by P fertilizers and lime applicationPublication . Auxtero, E.; Madeira, Manuel; Monteiro, M.C.H.Phosphorus (P) deficiency is the major constraint to crop production in most tropical soils (Sahrawat et al., 2001). In Angola, such constraint (i.e, low concentration and low P solubility) has also been reported to limit crop production in many agricultural soils (Ucuassapi, 2006). These soils may require application of inorganic P through soluble and relatively reactive phosphate rock sources, and lime (Dobermann et al., 2002; Murphy, 2007). However, appropriate P management strategies may require information on the fate of applied P and its interaction with the colloidal constituents. Therefore, information on the different P fractions (inorganic and organic) after the application of different rates of P fertilizers and lime, as fractionated sequentially by the Hedley modified procedure (Tiessen and Moir, 1993) is crucial for making appropriate fertilizer and lime rate recommendations for crops (Islam et al., 2010).
- Phosphate desorption in luvisols and solonetz from a Mediterranean regionPublication . Monteiro, M.C.H.; Monteiro, Fernando; Madeira, ManuelTransfer of P from soil to water is controlled by the P retention capacity in the solid phase, namely by the equilibrium between adsorbed and precipitated forms. Desorption of P and/or phosphate dissolution govern the amount of P released into drainage water, runoff or freshwater. Soil P evaluated by Olsen method showed a strong correlation with the capacity of soil to desorb P and, within certain limits, to the transfer of P to water. This transfer of P relates to losses that occur either in surface horizons, or in subsurface horizons (to drainage water, to runoff or by soil erosion to freshwater).