Improving fertigation scheduling by combining continuous monitoring and numerical modeling of the root zone

In recent years, tremendous progress has been made in making the information gathered by sensors located on agricultural fields available almost immediately. Transferring the data directly to the cloud and rapidly presenting it to researchers, decision-makers, and farmers assist in optimally determining the timing, amount, and composition of fertigation. There have been ongoing efforts to reduce the technological and economic barriers to the efficient and reliable use of sensors that continuously monitor the root system’s heterogeneous and dynamic nature. Despite this, there are still many open questions related to determining the structure and installation locations of the sensors, the optimal algorithm with which the scheduling is determined, and how different sensing methods are combined to make optimal decisions. Sensor development is usually done using in situ experiments. These complex and expensive experiments ultimately result in a long development time. Using numerical models may accelerate the development of sensing methods and the selection of the optimal algorithm for fertigation. Numerical models are used as a research tool for understanding, quantifying, and predicting phenomena and processes in the soil-plant-atmosphere system and for planning and managing water resources and their quality, including irrigation and drainage. Despite their complexity, numerical models are increasingly used thanks to a better understanding of water flow and solute transport processes, the development and improvement of mathematical methods for solving governing equations, and the accelerated development of computers capable of calculating different processes simultaneously in small intervals of time and space. The presentation will review three sensing methods and present a combination of models that solve the water status and the fertilizer concentration in the root zone. The methods that will be reviewed are a) a tensiometer for measuring soil pressure heads, b) a suction cup for inferring soil solution concentrations, and c) a minirhizotron for evaluating the root system structure. Determining optimal fertigation undoubtedly requires a multidisciplinary approach that considers the root zone’s physical, chemical, and biological characteristics. The combination of continuous measurements and numerical models may improve decision-making regarding resource application, thus optimizing the use of water and fertilizers while increasing economic profit and reducing environmental impacts.