Increased plant growth in response to mulching has been attributed primarily to
conservation of soil moisture, moderation of soil temperature, and reduced competition with turf
and other plants (e.g. Watson, 1988; Greenly and Rakow, 1995; Iles and Dosmann, 1999). In our
study, neither of the mulches had any effect on soil moisture or average soil temperature in the
rooting zone (depth of 15 cm), and plots were fastidiously weeded, so these variables were not a
factor (Lloyd, 2001). Rather, the primary effects of mulches were conclusively linked to the
impacts of their C:N ratio on microbial biomass and nutrient cycling as they decomposed.
Clearly, understanding the dominating influence of soil microbes on nitrogen availability is key
to understanding the dynamics of soil fertility.