Challenging assumptions about the effects of elevated CO2 on crops: soybean field trials show that intensifying drought eliminates the expected benefits
This paper by researchers in the US and Australia reports the findings of a long-term field-trial-based investigation into the effect of elevated carbon dioxide concentrations (CO2) on soy yield and drought tolerance. Their findings challenge the widely-held belief that crop yield will be increased by elevated CO2 (the so-called CO2 fertilisation effect) both because of increased photosynthetic rate, and because of lower susceptibility to drought: it has long been assumed that in higher CO2 conditions, stomatal conductance will be lower, leading to slower water loss from the leaves, slower water uptake from the roots, and consequently more moisture remaining in the soil for longer, thereby sustaining crops in limited rainfall.