Abstract--In tropical forests, soil nutrients, microbes and microarthropods are patchy at multiple scales. Here we explore how all three interact to generate patchiness in decomposition. We arrayed 10x10cm litterbags along a ridge in a Panama rainforest to test top-down (via grazing by microbivores like isopods and diplopods) and bottom-up (via nutrients) effects on the decomposition of hemicellulose. A 1000-fold gradient in mesh size generated a two-fold gradient in arthropod grazing. Unlike many green food webs, arthropod grazers ultimately enhanced decomposition rates (and hence microbial activity) after first retarding it.  Micropulses of N and P (to simulate concentrated urine) enhanced neither decomposition rates nor grazer abundance. instead cascading upwards to increase the abundance of predacious ants. At larger scales, decomposition rates varied across the ridge, and were highest in a plot with intermediate litter depth, moisture, and insolation. These data support the working hypothesis that, at the 10x10 cm scale, N and P cascade upward to enhance a major predator guild in the litter, which in turn suppress grazers that have a net facilitative effect on decomposition. These small-scale effects are in turn embedded in mesoscale variability linked to soil moisture and perhaps tree species.