Soil-microbial response to sugarcane filter cake and biogenic waste compost
2008
Ghulam Rasul. | Khan, Khalid S. | Müller, Torsten | Joergensen, Rainer Georg
An incubation experiment was carried out to examine the N-immobilizing effect of sugarcane filter cake (C : N = 12.4) and to prove whether mixing it with compost (C : N = 10.5) has any synergistic effects on C and N mineralization after incorporation into the soil. Approximately 19% of the compost-C added and 37% of the filter cake-C were evolved as CO₂, assuming that the amendments had no effects on the decomposition of soil organic C. However, only 28% of the added filter cake was lost according to the total-C and δ¹³C values. Filter cake and compost contained initially significant concentrations of inorganic N, which was nearly completely immobilized between day 7 and 14 of the incubation in most cases. After day 14, N remineralization occurred at an average rate of 0.73 μg N (g soil)⁻¹ d⁻¹ in most amendment treatments, paralleling the N mineralization rate of the nonamended control without significant difference. No significant net N mineralization from the amendment N occurred in any of the amendment treatments in comparison to the control. The addition of compost and filter cake resulted in a linear increase in microbial biomass C with increasing amounts of C added. This increase was not affected by differences in substrate quality, especially the three times larger content of K₂SO₄-extractable organic C in the sugarcane filter cake. In most amendment treatments, microbial biomass C and biomass N increased until the end of the incubation. No synergistic effects could be observed in the mixture treatments of compost and sugarcane filter cake.
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