Interactions in the soil-plant-water system as a basis for landscape-adoptive planning of carbon sequestration in agroecosystems along natural moisture gradient

The key for implementation of sustainable development goals in land management is in multifunctional paradigm of landscape usage. A lot of scientific efforts were done since 1980s (e.g. Kiryushin, 2019) to develop a landscape-adaptive system which is in essence addressing

1) spatial distribution of plant varieties and farm operations adapted to topographical and lithological landscape features 2) temporal tuning of crop phenology to regional and even local weather conditions. This system proved especially useful in increasing the yield and yet reducing pollution level in experimental settings. However, there were no boost of implementation in the country of origin-Russia- due to number of reasons, social and economical included. The rapid growth of carbon tax and carbon market provides a new window of opportunity for landscape adaptive agriculture, but only in case documented benefit for carbon sequestration could be shown. Here we present theoretical proof of concept based on integrated critical zone model, 1D-ICZ (Giannakis et al, 2017), that couples computational modules for soil organic matter dynamics, soil aggregation and structure dynamics, bioturbation, plant productivity and nutrient uptake, water flow, solute speciation and transport, and mineral weathering kinetics. The model was applied to study C sequestration soil function along the regional natural soil moisture and temperature gradient. Calibration was done for three soil types (Retisols, Phaeozems, Chernozems) of increasing moisture deficits representing the well-drained landscape shoulder positions with an automorphic regime and hydromorphic footslope positions. The scenario simulation included the change in relative frequency of weather condition with low and extremely low, but also high end extremely high precipitation (from IPCC set of climate models). The model explicitly couples water infiltration storage and supply to soil structure and pedotransfer functions varying with meteorological conditions. This interaction allowed to select the current soil configuration and usage or structural and biogeochemical change in each soil and each scenario that are presumably most beneficial for C sequestration. The role of climate variables was maximum for automorphic regime and decreased with the decreasing distance to ground water. The soil textural, structural, and chemical properties on opposite played the major role on footslope positions. Accordingly, optimal land management option that promote corresponding soil structure, organic matter input and soil climate is proposed and discussed in balance with other soil functions.