MSc

Soil respiration (Rs), the second largest terrestrial carbon (C) flux, is becoming an essential area of study under rising global atmospheric carbon dioxide (CO2) and more intense climate change patterns. Erosion-induced soil degradation is predicted to rise with climate change. However, there is a debate on whether soil functions primarily as a C sink or a source of atmospheric CO2 during erosion. The Indian Himalayan region is one of the world's significant soil erosion hotspots. Increased agriculture in these landscapes due to population growth and rising food demands may worsen climate change if soil management is improper. There is a notable lack of study on the role of vertical soil mixing, a prominent process in eroding landscapes that involves mixing topsoil and subsoil and is accelerated by tillage practices. We selected a 6% sloped agricultural field and simulated the vertical soil mixing by manually combining the topsoil and subsoil in a 1:1 ratio at distinct slope locations of conventional (CT), minimum (MT), and no-tilled (NT) plots. Rs measurements were taken from topsoil, subsoil, and mixed soil across all the slope locations. The average mixed-soil Rs rates from mid-slope and downslope locations of NT, MT, and CT were 0.2027 ± 0.0352 and 0.1727 ± 0.0266 g CO2 m 2h-1, 0.1821 ± 0.0232 and 0.1780 ± 0.0227 g CO2 m-2 h-1, 0.1562 ± 0.0118 and 0.1524 ± 0.0070 g CO2 m-2 h-1, respectively. Observed rates of Rs were substantially lower than the expected rates at all the slope locations. The findings indicate that vertical soil mixing due to tillage and erosion will result in negative priming and reduce Rs rates, promoting C storage in tilled plots at mid-slope and downslope locations. In the context of climate change mitigation in hilly areas, proper management strategies need to be explored. The prevailing trend of transitioning to no-till practices for climate change mitigation needs to be further investigated in eroding agricultural areas for climate change mitigation.