INFLUENCE OF TRACE ELEMENT FERTILIZATION ON THE DECOMPOSITION RATE AND PHOSPHATASE ACTIVITY OF A MESIC FIBRISOL

Abstract

Determinations were made of the relative decomposition rates of samples taken from pasture plots on a blanket bog which had been drained, limed and variously fertilized for 8 yr. Under all three temperature regimes of incubations employed in the laboratory, samples of plots receiving fritted trace elements (FTE) and NPK fertilizers lost significantly less (22–29%) carbon than those of plots treated annually only with NPK. Subsequent measurements of bulk densities of the field plots confirmed the mitigating effect of FTE applications on biological degradation and humification of this organic soil. Chemical analyses and preliminary trials indicated that the increased Cu levels in the FTE-treated soils, although obviously not biocidal, may have inactivated some extracellular degradative enzymes in the soil at an accelerated rate, thus slowing degradation. Acid phosphatase activity was studied as an example. Indeed, this activity, both before and after laboratory incubation, was significantly lower in the FTE + NPK-treated material than in the one treated annually with NPK alone. The former also inactivated (in 20 h) 30% more of an added acid phosphatase preparation than did the latter. Also, this and several other organic soils lost significant proportions of their phosphatase activities upon incubation with 0.5% Cu. This treatment with Cu also curtailed the loss of carbon as CO2 from samples of the pasture plots on the Mesic Fibrisol.