Browsing by Author "Vasconcelos, E."
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- Avaliação do estado nutricional azotado de pés-mãe de Eucalyptus globulus Labill. ssp. globulus com recurso a um medidor portátil de clorofilaPublication . Vasconcelos, E.; Ribeiro, H.M.; Ramos, A.; Coutinho, J.With the aim of evaluating the use of the portable chlorophyll meter “MinoltaSPAD 502” readings (SPAD readings) as an indicator of the nitrogen status of Eucalyptus globulus Labill. ssp. globulus (E. globulus) mother plants, a nitrogen fertilization experiment with this species was performed. Mother plants of two clones (HD 161 and CN5) of E. globulus were grown in an open-air nursery, in 12 L pots. Plants received 5 different nutrient solutions containing 50, 100, 200, 400 e 800 mg N L-1. During 1999, mother plants were subjected to a formative pruning. During 2000 and 2001 the following parameters were evaluated: number of cuttings produced, rooting ability of the cuttings, nitrogen content of the youngest fully expanded leaf, and leaf SPAD readings. Results obtained showed a significant asymptotic relationship between nitrogen availability and SPAD readings and a linear, positive and significant relationship between SPAD readings (y) and nitrogen leaf contents (x, g kg –1): y=23,27+0,75x; r=0.94; n=150. Results also showed a good fitting of quadratic model to the relationship between SPAD readings and the mother plants production (cuttings production and rooting ability of the cuttings). The determination coefficients (78%) were similar to those obtained when the model was adjusted to the relationship between leaf nitrogen and mother plants production (80%). Results indicate that, in this experiment, SPAD readings can be used to evaluate nitrogen status of E. globulus mother plants with a diagnostic “quality” similar to leaf nitrogen contents
- Carbon and nitrogen mineralization of organic wastes from sugarcane distilleries: vinasse and yeast wastePublication . Vasconcelos, E.; Cabral, F.; Pita, V.; Fangueiro, D.; Ribeiro, H.M.In Madeira Island (Portugal) significant amounts of wastes are generated in sugarcane distilleries, namely vinasse (the remaining fermented must after distillation) and yeast waste (the yeast surplus produced during the alcoholic fermentation). These wastes have high organic loads and low pH, leading to serious environmental problems when released directly into natural watercourses or when poorly managed (Hati et al., 2007). As a solution to avoid expensive treatments, both wastes have been used as soil amendment, since they contain important amounts of plant nutrients and organic matter (Resende et al., 2006; Parnaudeau et al., 2008). Indeed, application to soils of vinasse is a common practice in sugarcane cultivated areas and can fully substitute K and partially P on crops fertilization. Nevertheless, additional mineral nitrogen fertilization is needed when vinasse is spread in the soils (Junior et al., 2007; Oliveira et al., 2009). On the other hand, yeast waste has been considered as an excellent potential source of nitrogen for plant nutrition when applied to soils (Rezende et al., 2004). Thus, combined application of both wastes should ensure a more balanced supply of nutrients to plants. However, scarce information is available on the combine use of both wastes as fertilizer. The main objective of this study is to assess the effect of the combined application to soil of both organic materials (vinasse and yeast waste), and to evaluate its subsequent effects on nitrogen mineralization/immobilization process to supply nitrogen to crops and to preserve/restore soil carbon.
- Effect of the pig slurry separation techniques on the characteristics and potential availability of N to plants in the resulting liquid and solid fractionsPublication . Fangueiro, D.; Lopes, C.M.; Surgy, S.; Vasconcelos, E.Solid-liquid separation of slurry is used to obtain a solid (SF) and liquid fraction (LF), both used as organic fertilisers. Previous works showed that the separation technique used influences the composition of the resulting SF but no data are available relative to the LF. Four commonly used separation processes were considered e centrifugation, sieving, enhanced settling by the addition of cationic polyacrylamide (PAM-), and sediment settling as well as a recent sequential process e sieving followed by PAM addition to the resulting LF. The resulting LFs and SFs were comprehensively characterised and the amount of N potentially available for plants after incorporation to soil was also evaluated. Except for slurry that was only sieved which was very similar in composition to whole slurry (WS), the SFs and LFs had, respectively, higher and lower, concentrations of nutrients and organic matter (OM) than the WS. The ratio of ammoniacal to total N in the LFs varied from 0.33 to 0.92 whereas the values in the SFs varied between 0.16 and 0.31. The N:P:K ratio was also significantly influenced by the separation technique. Less than 10% of the total N applied in the WS, SFs or LFs was found to be potentially available for plants and, in some LFs, N immobilisation occurred after soil application. Since separation technique strongly influences nutrient distribution between LF and SF, as well as N speciation, the choice of the technique has to consider the final use of the resulting fractions as well as acquisition and operating costs.
- Effects of eucalypt residue management on nutrient leaching and soil propertiesPublication . Gómez-Rey, M.X.; Vasconcelos, E.; Madeira, ManuelEffects of harvest residues on nutrient leaching and soil chemical properties were studied in a lysimeter experiment. Treatments were: (A) forest Xoor litter and harvest residues, other than branches, incorporated into the soil, (B) as A, but with branches cut in 20 cm long bits and placed on the soil surface, (C) as B, but with bits incorporated into the soil, (D) as B, but with branches chopped into chips, (E) as C, but with branches chopped into chips, (F) forest Xoor litter and harvest residues on the soil surface, with branches cut in 20 cm long bits, (G) as F, but with branches chopped into chips, and (H) absence of harvest residues (control). Treatments were applied in zero-tension lysimeters containing 25 kg of soil. Leachates were collected for a 6-year period. At the end of the experiment, lysimeters were dismantled and soil was divided in four layers. Residues, other than branches, increased N leaching, as compared with the control. Branches on the soil surface reduced N leaching when cut in chips. Branches incorporated into the soil reduced leaching independently of their size. Organic residues on the soil surface showed similar effect to those incorporated into the soil. However, harvest residues on the soil surface increased leachate volume, and reduced Ca and P losses. Such a placement of residues led to high contents of Ca and P in the 0–5 cm top soil layer Contents of organic C, total N and base cations were not affected by the treatments.
- Effects of organic residue management and legume cover on growth of pine seedlings, nutrient leaching and soil propertiesPublication . Gómez-Rey, M.X.; Madeira, Manuel; Vasconcelos, E.• The short-term effect of organic residue management on the growth and nutrition of Pinus pinaster Ait. seedlings, and on nutrient leaching and chemical properties of an acid soil was assessed through a lysimeter experiment. Treatments included absence, placement on the soil surface, and incorporation into the soil (with and without legume cover cropping) of organic residues (forest floor litter or forest floor litter plus harvest residues). • Residues placed on the soil surface enhanced seedling growth. Organic residues reduced nutrient losses (NO− 3 , Ca andMg) and resulted in nutrient accumulation in the soil. Harvest residues positively affected K seedling nutrition status and enhanced K soil accumulation. • Legume cover cropping reduced soil nutrient losses (N, Ca, Mg and K) during the early stage of seedling growth; it also improved seedling nutrition status (N and P), but without any effect on growth. • Harvest residues plus forest floor litter placed on the soil surface was the most appropriate management to both reduce nutrient losses through leaching and increase height of seedlings at the end of the experimental period (two years).
- A fertilização azotada de pés-mãe de Eucalyptus globulus Labill.: efeito no crescimentoPublication . Vasconcelos, E.; Ribeiro, H.M.; Ramos, A.; Coutinho, J.To asses the effect of N fertilization on the growth of E. globulus stock plants, a nitrogen fertilization experiment was performed. During 3 years, stock plants of 2 clones (HD161 and CN5) were fertilized with complete nutrient solutions containing 5 different levels of N (50, 100, 200, 400 and 800 mg N L-1). Total biomass, leafbiomass, leaf area and number of shoots produced during the 3 years period were measured. Increasing levels of applied nitrogen till 400 mg N L-1 led to a significant increase of both biomass and shoot production. However, these productions were not significantly affected when N fertilization increased from 400 to 800 mg N L-1. Increasing levels of applied nitrogen also led to an increase of: i) total leaf area ii) specific leaf area (29% increase) and iii) leaf area ratio (13% increase), showing that with a higher N availability stock plants tend to improve their photosynthetic apparatus. Results show that nitrogen is a fundamental nutrient for the growth of E globulus stock plants and, as a consequence, nitrogen fertilization must be optimized. The maximum growth of E. globulus mother plants was achieved with 400 mg N L-1.
- Influence of the particle size and animal slurry type on the potential of nitrogen mineralization after soil incorporationPublication . Fangueiro, D.; Gusmão, M.; Grilo, J.; Vasconcelos, E.; Cabral, F.Animal manures are rich in organic matter and nutrients, namely nitrogen (N) and, consequently, widely applied to soil as organic fertilizers. However, a large part of the nitrogen contained in animal manures is in the organic form and so not directly available for plants. Indeed, organic N has to be mineralized prior to plant uptake (Rees and Castle, 2002). Several manure characteristics as the C:N ratio (Chadwick et al., 2000), the lignin content (Kristensen, 1996) and the NH4 +/organic N ratio (Beauchamp and Paul, 1989) have been suggested as indicators of the plant-available N. More recently, Fangueiro et al. (2008) showed that the potential of N mineralization (PNM) of cattle slurry is inversely correlated with slurry particle size: finest fractions are the particle-size fractions from which N mineralization occurs in slurries whereas coarser fractions are associated with immobilization. Furthermore, Moller et al. (2002) reported that animal diet and anaerobic decomposition during storage in slurry channels and stores affect the slurry particle size distribution. Such information is of great interest since the finest slurry particle size should infiltrate the soil more easily and quickly relative to the coarser slurry particle size that should remain close to soil surface. Furthermore, mechanical slurry separation is now performed in many pig and dairy farms in order to improve slurry management in terms of nutrients utilization and reducing costs related to slurry storage. Slurry separation by screw press leads to a nutrient rich organic solid fraction (0.7– 3.2 mm particles) that may be composted and a liquid fraction that can be used for fertigation. In the present study, three types of slurry (pig, duck and cattle) were separated into 4 slurry particle size fractions (>2000 um, 2000-500 um, 500-100 um, <100 um) in order to assess the influence of the type of slurry and slurry particle size on the PNM after soil incorporation.
- Proportion, composition and potencial N mineralisation of particle size fractions obtained by mechanical separation of animal slurryPublication . Fangueiro, D.; Gusmão, M.; Grilo, J.; Porfirio, G.; Vasconcelos, E.; Cabral, F.Mechanical slurry separation is a useful technology for slurry management on farms. The characteristics of the fractions obtained depend on the separation efficiency and on the characteristics of the original slurry. In the present work, three types of slurry e pig, cow and duck e were separated into 4 particle size fractions. The proportion, composition in terms of carbon and nutrients as nitrogen (N) phosphorus (P) and potassium (K) was evaluated. The potential of N mineralisation of whole slurries, and each fraction after soil application, was assessed. Results of the study showed that the characteristics of the slurry fractions obtained depend strongly on the slurry type considered, namely on its dry matter (DM) content. A positive value of PNM was observed with the 3 slurry types and 4 fractions considered, indicating that no N immobilisation occurred. Nevertheless, results showed that the value of PNM vary significantly (P < 0.05) with slurry types and slurry particle size fractions.
- Use of pulp mill inorganic wastes as alternative liming materialsPublication . Cabral, F.; Ribeiro, H.M.; Hilário, L.; Machado, L.; Vasconcelos, E.A laboratory aerobic incubation study was performed during 18 weeks under controlled conditions to assess the effects of applying different doses of pulp mill inorganic wastes on the physical–chemical properties of an acid Dystric Cambissol. Three different inorganic wastes were tested – wood ash, dregs and grits, and an agriculture limestone was used as reference. Results showed that increasing the dose applied of the different inorganic wastes tested always led to significant raises of soil pH at different incubation times demonstrating that its use as alternative-liming materials could be a valid and less expensive option to the use of commercial agricultural limestone. Moreover, no immediate concerns seem to be expected related to soil exchangeable sodium (Na) content, at least for the doses needed to increase soil pH until the targeted value 6.5. Particularly for wood ash a pronounced increase on soil extractable potassium and phosphorous was observed, indicating that besides the liming effect this waste can contribute to improve soil fertility by supplying significant available amounts of these nutrients. Finally, metals do not seem to be a limiting factor for the application to land of these byproducts