The effects of Fe- and Mn-oxides and imogolite in the presence of kaolinite on organic nitrogen mineralization and soil enzyme activities

An incubation experiment was conducted to study the effect of clay content and composition on organic nitrogen mineralization. The measured mineralization from alfalfa residues, enzyme activities, microbial biomass in mixtures sand, kaolinite, non-layered colloids (NLCs) with sand as a control. found that contents kaolinite NLCs increased, activity decreased, but increased. maximum decrease 88.6%, increased 4.7 15.5%. acid alkaline phosphatase activities also decreased by 86.0 93.6%, respectively, an increase content. specific surface area (SSA) showed inverse relationship nitrogen. Inactivation extracellular enzymes adsorption surfaces NLCs, accessibility substrate molecules due adsorption, reduced Microbial water holding capacity indicating importance water-filled pores accommodating active protecting it desiccation predators.