Litter decay rates often correlate with the initial ratios of lignin : nitrogen (N) or lignin : cellulose in litter. However, the chemical and microbial mechanisms that give rise to these patterns are still unclear. To identify these mechanisms, we studied the decomposition of a model plant system, Arabidopsis thaliana , in which plants were manipulated to have low levels of lignin, cellulose, or litter N. Nitrogen fertilizer...