Testing a Soil Moisture Sensor Based Irrigation Controller in both Laboratory and Field Conditions for Fargo Silty Clay Soils

Abstract

Highlights A soil matric potential sensor-based irrigation system was tested in lab and field experiments. Soil matric potential and soil moisture levels for each threshold were determined for Fargo silty clay soil through lab experiment. Thresholds 5, 6, 7, and 8 at -35, -45, -55, and -70 kPa were tested through the field experiment for watermelon production. Abstract. Irrigation scheduling plays a pivotal role in water management. Conventional irrigation methods often struggle to maintain consistent moisture across fields due to uniform water application irrespective of field conditions and soil moisture levels. Automatic soil moisture sensors offer a solution by tailoring irrigation based on field conditions. These systems trigger irrigation when soil is too dry or skip it when moisture levels are sufficient. Hence, setting the right threshold value is key for sensor-based irrigation. This study involved laboratory testing of an irrigation controller, and determining soil matric potential and volumetric water content at various thresholds (1 to 9) for Fargo Silty Clay soil. Subsequently, a field experiment assessed its performance for a drip irrigation system at different thresholds (5, 6, 7, and 8) for watermelon cultivation, both with and without clear plastic mulch, in a randomized layout. Thresholds 5, 6, 7, and 8 (-35, -45, -55, and -70 kPa), along with no irrigation, were considered with one irrigation event daily. Results from laboratory and field tests underscore the controller’s efficacy in managing drip irrigation timing and duration. Notably, threshold 7 (-55 kPa) combined with clear plastic mulch emerged as the most optimal treatment, yielding the highest watermelon production of 129.6 tons/ha. Moreover, this approach delivered premium produce quality, but utilizing only 142.2 mm of irrigation water. This study emphasizes the role of precise irrigation scheduling. By integrating smart technology and thoughtful threshold setting, agricultural practices can be elevated, yielding abundant crops while conserving water and promoting sustainability. Keywords: Controller, Drip irrigation, Mulch, Sensor, Watermelon.