Nitrogen mineralisation and the activity and populations of microflora in a high producing yellow-brown loam under pasture

摘要

At 25#xB0;C, optimum N-mineralisation in a topsoil sample from a yellow-brown loam under high-producing pasture was observed in the laboratory at 80 moisture (by weight). Populations of ammonium-oxidising bacteria and moulds did not differ significantly at soil moisture levels of 20, 40, 80, and 140 by weight, but 20 moisture reduced the populations of total aerobic bacteria, gram negative bacteria, fluorescent Pseudomonas spp., and nitrite-oxidising bacteria. Liming with Ca(OH)2(equivalent to 2500 kg.ha#x2013;1, pH 7.0) did not increase N-mineralisation but increased CO2evolution. Liming also increased total aerobic bacteria, gram negative bacteria, and the biomass carbon level.