Land cover plays a critical role in shaping nutrient availability within aquatic ecosystems. Although changes in river nitrogen (N) and phosphorus (P) have received considerable attention, the effects of human activities on river silicon (DSi) remain relatively understudied. To address these knowledge gaps, our team developed the Global Aggregation of Stream Silica (GlASS) dataset, which compiles stream nutrient chemistry (Si, N, P), discharge data, and watershed characteristics from more than 400 rivers spanning all seven continents and compiling data from over 20 research networks. We used this dataset to assess long-term changes in river Si concentrations and fluxes, the relationship of Si to discharge and N and P, and the mechanisms driving Si behavior. We documented long-term changes in annual river Si dynamics that differed across land use/cover types, with trends most apparent in high latitude and alpine systems. Although long-term Si trends were largely decoupled from those of N and P, we observed that Si seasonality was strongly linked to river nutrient availability and land use/cover. Finally, after accounting for lithology, we found that annual Si concentrations and yields were closely associated with terrestrial productivity, river nutrient status, and land cover. Collectively, these results highlight that multiple aspects of river Si dynamics are sensitive to land use and land cover, specifically shifts in river nutrient status and terrestrial productivity.