Well... You do need to account for the lost inputs, e.g. fertilizer that runs off instead of being sequestered, water pumped in for irrigation, gasoline to powe

Well... You do need to account for the lost inputs, e.g. fertilizer that runs off instead of being sequestered, water pumped in for irrigation, gasoline to power a tractor, and so forth. A cover crop (e.g. clover) specifically for building soil that grows without aid of fertilizer or irrigation is a better story in this regard.