There are several plant below-ground biomass databases for grasslands, but the contribution from the southern hemisphere is minimal. Particularly, no study has compiled the published values of plant below-ground biomass for the temperate subhumid grasslands of South America. In these grasslands, called Río de la Plata grasslands, grazing is the most frequent disturbance. We set two objectives: (1) to compile and synthesize data of four variables: below-ground biomass, fraction of total biomass allocated below-ground, below-ground net primary productivity and below-ground biomass turnover rate; (2) to estimate the effect of grazing exclusion on below-ground biomass by means of a meta-analysis. There are 15 studies published on six out of eight regional sub-divisions of the Río de la Plata grasslands. © 2023 Ecological Society of Australia.