The secondary oxidation of amino-acids by the catechol oxidase of belladonna

Abstract

LEES I948the same equation was found to apply to data from experiments in which the equilibrium distributions of copper between soil and 0-33M-Na2SO4 solution were determined for both a good and a bad soil under wide variations of experimental conditions (Fig. 3).Data in Table 1 show, as might be expected, that the equilibrium concentration of copper in 033m-Na2SO4 against a given concentration of copper on the SOM is independent of the solution volume. DISCUSSIONIn comparison with good Trinidad cacao soils, bad cacao soils are characterized by a low power to retain copper in complex with the SOM.Although the copper-retaining power of a soil is clearly related to its SOM content, the relation is not linear, and nearly all the bad soils lie on or near the steeply descending portion of the curve relating copper retention and percentage of SOM in the soil.Traceelement deficiencies, induced either by leaching or by a too great uptake of trace elements by past cacao crops, are, therefore, far more likely to occur in bad than in good soils.Although difficulties in estimating small per- centages ofSOM in all probability caused the scatter of the points on the descending part of the copper- retention curve (Fig. 1), there is reason to believe that of the total value for percentage of SOM, as given by the method used, some 2-5 % represents absorptively inactive SOM.If it be assumed that some 2-5% of the SOM is adsorptively inactive, two widely different soils give the same adsorption isotherm (Fig. 3), a fact that suggests there is no basic difference between the absorptive capacities of the organic fractions or the two soils.It is reasonable to infer from Fig. 3 that the saturation capacity of SOM is about 1400 p-equiv.Cu/g., to which value the logarithmically plotted Freundlich isotherm, known to be non-linear near saturation of the adsorbent, is asymptotic.SUMMARY 1.Some bad Trinuidad cacao soils have lower contents of organic matter, and lower copper- retaining powers than good soils.2. The distribution of copper between a soil and a solution in equilibrium with it follows a Freundlich isotherm.3. The significance of the results is discussed.