Soil Organic Matter Stabilization/Destabilization: Input Removal Exposes the Controls.

Soil organic matter formed from plant detrital inputs plays a critical role in the soil ecosystem, as a source of energy for organisms, nutrients for fertility, and carbon for exchange with the atmosphere.  Thus litter removal, long a side effect of conventional management practices, leads to declines in soil fertility, carbon storage, and physical structure through the reduction of organic matter content. Sometimes, you don’t know what you’ve got until you’ve lost it:  purposeful manipulative experiments and inadvertent organic matter removal through conventional practices both often reveal aspects of the ecology of soil carbon dynamics through the process of elimination. Much like the “priming effect” represents an integrative ecosystem process centered around input additions, elimination or removal experiments can peel away at the intertwined processes that protect soil organic matter from losses.   Examples ranging from the Detritus Input Removal Treatment (DIRT) forest network to managed zero-tillage agroecosystems in Hawaii will demonstrate this concept within the framework of the mechanisms controlling organic matter stabilization/destabilization.  The questions remain, however, how much of the lost functioning can be regained through better, more sustainable practices, and how resilient will rebuilt soil ecosystems be to future climate and land use changes?