Comparative analysis of water budgets across the U.S. long-term agroecosystem research network

•We developed water budgets for 18 Long-Term Agroecosystem Research sites.•We estimated uncertainty of all the water budget components.•The average water budget uncertainty was 25% of precipitation.•Uncertainties were greatest for percolation and evapotranspiration.•LTAR sites span a 0.4 – 1.1 evaporative fraction and a 0.8 – 4.8 aridity index.