Soil characteristics and allometric models for biometric characteristics and nutrient amounts for high yielding "Bolaina" (Guazuma crinita) trees.

The Peruvian amazon is very diverse in native forestry species, the Guazuma crinita "Bolaina" being one of the most planted species in the country; however, little or no information about soil requirements and nutrient demands is known. The objective of this work was to assess the general conditions of soil fertility, biomass and macro- and micronutrient amounts in high-productivity Guazuma crinita plantations. Fields of high yielding Bolaina of different ages (1-10 years) were sampled in two regions. Soil and plant samples were collected in each field and biometric measurements of fresh weight, diameter at breast height and height were performed. For soil and plant analysis, both macro- (N, P, K, Ca, Mg, S) and micronutrients (B, Cu, Fe, Mn, Zn) were determined. Finally, allometric equations were constructed for biometric and nutrient amounts. This study is the first to assess and model macro- and micronutrient amounts in the productive cycle in this species, which grows in fertile soils. In the case of biometric equations, the logarithmic and logistic models performed better. For nutrient amounts, this species followed a pattern of Ca > N > K > P > S > Mg for macronutrients and Fe > B > Mn > Zn > Cu for micronutrients. The best prediction models for nutrients were the square root and logistic models.

Irrigation of eucalyptus plantation using treated bleached kraft pulp mill effluent.

The use of treated pulp mill effluent on eucalyptus plantation appears to be an attractive option for plant nutrition and water supply. It also constitutes a supplementary treatment process and a final disposal option for the mill effluent. This study aimed at the investigation and evaluation of the effects of bleached kraft pulp mill treated effluent on three typical Brazilian soils used for eucalyptus plantation. The effluent was characterized and five different application rates, defined according to the load of sodium, were tested in controlled environment experiments (greenhouse). After effluent application over a six month period an increase in the salinity of the studied soils was observed, although no soil dispersion was detected. The low content of some nutrients in the treated effluent indicated the need for fertilizer complementation. In general, the best biomass productivity and plant growth results were obtained in fine textured soil at a loading rate of 6.49 t Na ha(-1). The good response of the soil-plant system under different effluent application rates showed the feasibility for the eucalyptus irrigation if adequate management practices and monitoring are carried out.

Reduction of heavy metal contents in liquid effluents by vermicomposts and the use of the metal-enriched vermicomposts in lettuce cultivation.

The removal of Cu, Ni and Zn from electroplating effluents by adsorption in cattle manure vermicompost has been discussed. A glass column 38 cm long and 7 cm i.d. was loaded with cattle manure vermicompost and effluents were passed through it. The metal concentrations were measured in the elutant. The experiments on adding effluent aliquots into the columns were continued until the metal concentrations in the elutant reached the maximum values established for effluent discharges in water courses by the Brazilian quality criteria, i.e., Cu=1.0 mg L(-1), Ni=2.0 mg L(-1), and Zn=5.0 mg L(-1). The amount of Cu retention by the vermicompost was determined at the natural effluent pH (2.0). The Zn and Ni retentions were evaluated at the natural effluent pH (6.9 and 7.4, respectively) as well pH 2.0. Vermicompost residues obtained from this process were used for lettuce cultivation. The vermicompost was found to be efficient in removing metals from the electroplating wastes, as well as in the increase of its pH values. Metal retention values were close to 100%. The Cu concentrations in lettuce leaves from the treatment with vermicompost enriched with this metal were below the range of critical toxicity level to plants, i.e., from 20 to 100 mg L(-1). However, the estimated Cu concentrations in the roots from the treatment with vermicompost enriched with Cu were much larger than that of the treatment with the natural vermicompost, reaching 246.3 mg L(-1). The Ni and Zn concentrations in lettuce leaves from the treatments, with vermicomposts enriched with the respective metals, were above the range of critical toxicity levels to plants, i.e., from 10 to 50 mg kg(-1) and from 15 to 30 mg kg(-1), respectively. However, no symptom of toxicity was found visually. Larger accumulations of Cu, Ni and Zn were found in the lettuce leaves than in the roots after the treatments with the uncontaminated vermicompost. A greater absorption of Cu and Ni by roots was found in treatments with vermicompost enriched with these elements, whereas Zn was found preferentially in the leaves. The statistical analysis was done by analyses of variance and regression.

Responses of eucalypt species to aluminum: the possible involvement of low molecular weight organic acids in the Al tolerance mechanism.

Aluminum (Al) tolerance mechanisms in crop plants have been extensively researched, but our understanding of the physiological mechanisms underlying Al tolerance in trees is still limited. To investigate Al tolerance in eucalypts, seedlings of six species (Eucalyptus globulus Labill., Eucalyptus urophylla S.T. Blake, Eucalyptus dunnii Maiden, Eucalyptus saligna Sm., Eucalyptus cloeziana F. J. Muell. and Eucalyptus grandis w. Hill ex Maiden) and seedlings of six clones of Eucalyptus species were grown for 10 days in nutrient solutions containing Al concentrations varying from 0 to 2.5 microM (0 to 648 microM Al3+ activities). Root elongation of most species was inhibited only by high Al3+ activities. Low to intermediate Al3+ activities were beneficial to root elongation of all species and clones. Among the species tested, E. globulus and E. urophylla were more tolerant to Al toxicity, whereas E. grandis and E. cloeziana were more susceptible to Al-induced damage. Although E. globulus seedlings were tolerant to Al toxicity, they were highly sensitive to lanthanum (La), indicating that the tolerance mechanism is specific for Al. Fine roots accumulated more Al and their elongation was inhibited more than that of thick roots. In E. globulus, accumulation of Al in root tips increased linearly with increasing Al concentration in the nutrient solution. The majority of Al taken up was retained in the root system, and the small amounts of Al translocated to the shoot system were found mainly in older leaves. No more than 60% of the Al in the thick root tip was in an exchangeable form in the apoplast that could be removed by sequential citrate rinses. Gas chromatography/mass spectrometry and ion chromatography analyses indicated that root exposure to Al led to a greater than 200% increase in malic acid concentration in the root tips of all eucalypt species. The increase in malate concentration in response to Al treatment correlated with the degree of Al tolerance of the species. A small increase in citric acid concentration was also observed in all species, but there were no consistent changes in the concentrations of other organic acids in response to Al treatment. In all eucalypt species, Al treatment induced the secretion of citric and malic acid in root exudates, but no trend with respect to Al tolerance was observed. Thus, although malate and citrate exudation by roots may partially account for the overall high Al tolerance of these eucalypt species, it appears that tolerance is mainly derived from the internal detoxification of Al by complexation with malic acid.

Removal of Cu and Zn from swine raising wastewater using organic filters.

Rice husks, coffee bean skins, sugar cane bagasse, maize cobs, saw dust and fine charcoal dust were evaluated as filters for the removal of heavy metals (Cu and Zn) from the waste water of swine raising installations. The specific mass, pH and the sum of bases and removable acids were determined to characterize each of the filter materials. Each filtering material was placed in a 100 mm diameter, 600 mm long, PVC column to a height of 500 mm under 12,500 N m(-2) of compression. Chemical and physical analyses were determined on effluent samples collected for each 1.5 l up to a total of 15 l. The organic materials reduced the concentration of sediment solids (> 90%), total solids (up to 33%) and Cu (up to 43.6%) of the inffluent but had little or no effect on Zn concentration.