Effect of elevated carbon dioxide on soil hydrothermal regimes and growth of maize crop (Zea mays L.) in semi-arid tropics of Indo-Gangetic Plains.

To see the effect of climate change on the variation of soil hydrothermal regimes and growth of maize crop, an experiment was conducted in free-air carbon dioxide enrichment (FACE) facility during the kharif season of 2015 at Climate Change Facility of Indian Agricultural Research Institute, New Delhi, India. Under elevated CO2 and ambient condition, surface bulk density (BD) were 1.38 Mgm-3 and 1.44 Mgm-3, respectively but BD were not significantly different. During different days after sowing (DAS), in 0 to 10-cm soil depth, soil water content (SWC) in FACE varied between 14.58-20.70%, whereas in ambient condition, SWC variations were in between 19.33-22.94%. In 10 to 20-cm soil depth, SWC ranged in between 20.47-27.14% in FACE and 23.57-25.42% in ambient condition for different DAS. It is also observed that the arrival of peak surface ST was 1 h early in elevated CO2 condition. Photosynthetic rate increased by 5.7% on 44 DAS and 18.1% on 70 DAS under elevated carbon dioxide condition. Elevated carbon dioxide had reduced the stomatal conductance but the reduction was not significant. Like variation in air temperature for climate change, more intensive study is required to see the effect of climate change on soil temperature and its effect on crop growth.