Effect of climate change on nutrient cycling depending on plant community compositions

Dr. Muhammad Sana Ullah, Dr. Yakov Kuzyakov

Climate change in the 21st century will impact many aspects of the human and natural world, including agriculture sector. Under drought conditions, soil or atmospheric water deficits cause reduced stomatal conductance and leaf water potential, which restrict photosynthesis, leading to lower growth and yield. Besides carbon (C) input, soil moisture is also an important factor affecting ecosystem C exchange and soil organic matter decomposition. Taking action through traditional breeding or biotechnology to develop crops that are better adapted to future growing conditions will be aided by understanding the mechanisms driving crop responses to climate change.

Although C allocation strongly influences plant and soil processes, yet short-term C allocation dynamics in ecosystems and their responses to environmental changes are still poorly understood. We will investigate how drought stress may affect belowground C translocations, microbial communities and nutrient cycles, depending on plant community composition. To achieve these goals, we will conduct pot experiments under controlled conditions and following techniques will be used to these scientific questions:

·        Repeated 14CO2 pulse labelling of monocultures and mixture of maize and sorghum along with natural 13C abundance.

·        Plant physiological and biochemical parameters including stomatal conductance, transpiration and photosynthetic rates.

·        14C incorporation in plant parts, soil, microbial biomass, soil respiration (CO2 fluxes) and dissolved organic carbon (DOC).

·        Priming effects

·        Determination of isotopes by using IRMS (13C and 15N­) and Scintillation (14C and 33P) techniques.

·        Isotopic labelling with 15N and 33P and usage of Rb and Sr to study plant-microbial competitions for major nutrients (N, P, K and Ca) uptakes.

·        Soil physical fractionation including density and particle-size fractionation.

·        Microbial community composition and activities with determining total microbial biomass, PLFA, Extra-cellular enzyme activities and soil zymography with 14C imaging.