Use of Multisensor Capacitance Probes as Irrigation Management Tool in Humid Areas: Case Studies and Experiments from the Mid-Atlantic Region

Abstract

Multisensor capacitance probes (MCPs) were used to provide valuable and detailed information on soil water dynamics under irrigated farm management in Delaware. Near-continuous real-time soil water content and dynamics were measured at five soil depths within the rootzone of : 1) farmer-managed drip and sprinkler irrigation of several crops in 2002 and 2003; and 2) researcher-managed drip-irrigated watermelons (L. Citrullus lanatus) under irrigation rates of 50%, 100%, and 150% (low, medium, and high) relative to ET0 in 2004 and 2005. The objectives were to assess how these probes might be used to improve irrigation management and to examine the dynamics of soil water under humid conditions and typical grower management. The farmer-managed irrigations generally had a primary active rooting depth of 35 cm, but irrigation water was commonly observed to percolate to 100-cm depth. The high irrigation rate in the researcher-managed trials (more typical of farmer management) resulted in 29% of the irrigations causing water percolation to 70 cm, which was about six times the rate under medium irrigation. The yield of watermelon was not significantly affected by the wide range in irrigation amount, indicating that growers could reduce irrigation in humid conditions without impacting yield or quality. The use of MCPs would enable accurate monitoring of soil water trends and, in combination with weather forecasts, provide confidence that reducing typical irrigation amounts should not result in crop water stress or decreased yield.