Soil water dynamics using multisensor capacitance probes in nontraffic interrows of corn

Water is often the primary factor limiting plant growth, and it is the primary agent for moving plant nutrients and pesticides to streams and groundwater. This study was conducted to assess the capabilities of recently developed multisensor capacitance probes and monitoring systems to measure the dynamics of soil water content under longterm field-scale conditions, and to quantify in real time the spatial variation of soil water content under plow-tillage (PT) and no-tillage (NT) corn (Zea mays L). Probes were placed at eight nontraffic interrow locations, with cable lengths ranging from 25 to 125 m, on a 0.5-ha field site. The capacitance sensors were centered st four soil depths and readings were taken every 10 min by the data-logging system. Real-time dynamics of soil water change following 82 mm of rainfall in the spring were used to identify the apparent water-holding capacity within the sensor depths (5-55 cm) under NT as 171 mm and 155 mm under PT. Rates of soil water loss with a full canopy of corn were 90% of high evapotranspiration (ET) demand. Breaking points were observed and calculated between high and low rates of soil water loss, under full canopy and high ET demand. Changes from high to Low rates of soil water loss were more evident in PT plots (62% reduction) than in NT plots (46% reduction), At the end of three drying cycles during the growing season, there was an average of 37 mm more water (5-55-cm soil depth) under NT than PT. The multisensor capacitance probes proved to be highly sensitive and robust for field-scale, real-time, soil water research.