Mineralisation of organic matter in intact versus sieved/refilled soil cores

Abstract

In a 6-month laboratory incubation study, we compared the net C and N mineralisation of the soil organic matter (SOM) of 3 pasture soils and the mineralisation of glucose-C in intact versus sieved/refilled soil cores. The main questions were whether the net C and N mineralisation differed between intact and sieved/refilled soil cores after a conditioning period of 4 weeks, and how much the C and N mineralisation of SOM differed among the similarly managed pasture soils.

Apart from the net nitrogen mineralisation in one soil, there were no significant differences in cumulated mineralisation of C or N from SOM between the core types. In a fine-textured soil, net mineralisation of glucose-C differed significantly between core types, which was attributed to the different distribution of the amended glucose in intact and sieved/refilled cores. Net C and N mineralisation of SOM were closely correlated in the sieved/refilled cores, whereas no significant correlation was found in the intact cores. Expressing net C and N mineralisation as percentages of total soil C and N showed a more than 2-fold maximum difference between the soils in spite of similar long-term organic matter input. Subsequent studies should be done using more replicates and wider diameter, better controllable cores on ceramic plates.

CO2, net nitrogen mineralisation (NNM), soil microbial biomass.