Comparing crop growth and carbon budgets simulated across AmeriFlux agricultural sites using the Community Land Model (CLM)

•CLM4-Crop underestimated carbon emission at crop sites.•The energy and carbon exchanges of corn crops were better simulated than soybean.•GPP for soybean crops was significantly over-estimated.•CLM4-Crop underestimated water stress for both soybean and corn at US-Bo1.•New planting scheme and calibrated soybean parameters improved simulations.