A Unified Experimental Approach for Estimation of Root Zone Leaching of Applied Irrigation Water and Fertilizers.

Micro-irrigation methods have proven to be highly effective in achieving the desired crop yields, but there is increasing evidence suggesting the need for the optimization of irrigation scheduling and management, thereby achieving sustainable agricultural practices, while minimizing losses of applied water and fertilizers at the field scale. To optimize irrigation/fertigation practices, it is essential that irrigation and fertilizers are applied at the optimal concentration, place, and time to ensure maximum root uptake. Moreover, sound and sustainable irrigation systems must maintain a long-term salt balance that minimizes both salinity impacts on crop production and salt leaching to the groundwater. The applied irrigation water and dissolved fertilizer, as well as root growth and associated nutrient and water uptake, interact with soil properties and fertilizer source(s) in a complex manner that cannot easily be resolved with ‘experience’ and field experimentation alone. It is therefore that a coupled experimental-modeling study is required to allow for unraveling of the relevant complexities that result from typical field-wide spatial variations of soil texture and layering across farmer-managed fields. We present experimental approaches that provide the necessary soil data of soil moisture, water potential and nitrate concentration to evaluate and optimize irrigation water management practices using multi-dimensional modeling of unsaturated water flow and transport.