Resistance and resilience of soil biological indicators: A case study with multi walled carbon nanotube (MWCNT)

The soil ecosystem is experiencing stress due to climate change and the soil inhabitants will try to demonstrate their inherent resistance and resilience against those stresses. Due to wide application of nanomaterial as agricultural inputs, it could bring a shift in resistance and resilience pattern of soil microbes and associated enzymes, especially under short term heat stress. With this background, the impact of multi walled carbon nanotube (MWCNT) on resistance and recovery of soil biological indicators was examined. An incubation experiment was conducted for 90 days with varied concentrations (0, 50, 100, 250 and 500 mg kg-1) of MWCNT to assess its impact on soil enzyme activities and microbial population vis-à-vis their resistance and resilience indices under short term exposure to heat stress (48±2°C) for 24 hours. There was a reduction in enzymes activity after exposure to heat stress (7-22% in dehydrogenase activity, 4-27% in acid phosphatase activity, 7-33% in alkaline phosphatase and 10-26% in Fluorescein diacetate hydrolysing capacity). Resistance indices were enhanced for all the studied enzymes (+0.87 to +0.91); whereas there was no recovery of enzymatic activities after 90 days of incubation (-0.71 to -0.82). Like soil enzymes, resistance indices for the soil microbes followed the similar trend and were improved with MWCNT application (+0.61 to +0.86). MWCNT has the potential to improve resistance indices of the soil enzymes and the microbial groups, although they could not recover to their original state during periodical incubation. This study opens a route to understand the relative changes of biological indicators under MWCNT and their ability to withstand under heat stress.