Enhancing Crop Production and Soil Health: A Dual Approach with Process-Based Modeling and Continuous Soil Health Monitoring in Rainfed and Irrigated Agriculture in Tajikistan

Unsustainable agricultural management in Tajikistan's norther Laksh district has caused significant land degradation. Climate change and the related hydrological shifts further disrupt water management, particularly in irrigated systems. The current farming practices such as inefficient furrow irrigation with saline water and conventional soil cultivation hamper the soil's infiltration capacity, intensify runoff, and eventually degrade various ecosystem functions including crop production. Advanced Information and Communications Technology (ICT) based decision support systems e.g. for irrigation scheduling are under development; however, key soil parameters, including soil hydraulic properties, are largely unknown. As part of Caritas Switzerland's Weather, Water, Climate Services (WWCS) initiative, jointly funded with the Swiss Agency for Development and Cooperation, this research combines monitoring and modeling based approaches to investigate the local soil-water-crop processes and to eventually enhance the according management, functionality and productivity in both irrigated and rainfed agricultural systems. Field-assessed soil physical, chemical and biological properties serve as the benchmarks for establishing a Soil Health Index and crafting process-based modeling scenarios. In irrigated systems a surrogate modeling approach is employed combining Hydrus 2D and its Furrow submodule with AquaCrop. The establishment of the Soil Health Index is currently underway, with successive monitoring aimed at evaluating changes in soil health over time in relation to selected conservation practices. The assessment of soil hydraulic and physical properties has provided key parameters, including hydraulic conductivity, field capacity and permanent wilting point. Those parameters and knowledge can be directly integrated into ICT applications (e.g. weather-based irrigation advisory services) that optimize the use of scarce inputs (water, fertilizer, etc) within sustainable production systems; and simultaneously enhancing resilience to short term weather changes and longer-term climate change.