Slight Temperature Increases Affect Soil Respiration Under Short-Term Incubation: a Study Case from Agricultural Fields from Cuatro Cienegas, Mexico

By the end of this century, climate change is forecast to increase the average global temperature by between 1.4 and 5.8 degrees C. The effects of climate change on dryland farming systems are complex and time-varying. There is no consensus on how temperature increase will affect soil functioning and carbon dynamics. Therefore, we want to know to what extent a slight increase in temperature influences the respiration rate of the agricultural soils of Cuatro Cienegas Basin (CCB). Soils from six agricultural fields in the CCB, northeastern Mexico, were incubated for 17 days at the mean growing season temperature (36.4 degrees C) and under two climate change scenarios (temperature increased by 1.5 and 3 degrees C), with temperature and relative humidity set for each scenario. Soil respiration, moisture, and temperature were determined every 3 days. Soil physicochemical properties were determined for each agricultural plot. The results show that for the 1.5 degrees C scenario, an increase in soil respiration (R-S) at the beginning of incubation attributed to a higher microbial community activity, thus resulting in a higher decomposition of organic matter rate. During the following incubation days, this activity decreased due to substrate depletion or microbial thermal adaptation. R-S also followed the same pattern of increase and decrease throughout the incubation period of the 3 degrees C scenario. The total release of CO2 from the soil increased in both climate change scenarios, especially at 1.5 degrees C. Under a global warming scenario, agricultural soils in the CCB are expected to lose more labile carbon (potentially 50-66% more C release), with a possible response of microbial acclimation.