Absorption and Toxicity of Copper and Zinc in Bean Plants Cultivated in Soil Treated with Chicken Manure

The interaction between copper, zinc, and chicken manure, whenadded to soil, was studied in a greenhouse setting. Coppersulfate and of zinc chloride at concentrations of 0.5 to 2.0mmol kg^-1 were added separately to pots containing 3.0 kgof dystrophic dark red latosoil (LEd) plus 1,0% (m/m) pH 4.2chicken manure. IAPAR 57 beans were used as test plant andcultivated in the experimental soils for 30 days. Plant growthin terms of dry weight and the concentrations of copper and zincin the aerial part of the plants were determined. Bean plantingswere repeated four times, at four-month intervals. A 20%decrease in dry weight was observed when amounts of copper orzinc equal to or geater than 1.0 or 2.0 mmol kg^-1, respectively, were applied to the soil over an average of fourplantings. For these concentrations, the average amount of metalfound in the plant was 13.4 mg kg^-1 for copper and 224.8 mgkg^-1 for zinc. Chlorosis of the leaves in the bean plantswas also observed. The copper and zinc concentrations in thetreated soil were determined using different extractants. Amongthe solutions evaluated for the extraction of available zinc,1.0 M ammonium acetate, pH 4.8, showed a better correlation withthe metal concentration in the plant. As for copper, the bestcorrelation was found with the Mehlich-1 extractant.