ASABE Technical Library - Abstract

Abstract. The Food and Agricultural Organization of the United Nations (FAO) estimates only 20% of the land used to grow food is irrigated but it accounts for 40% of the world food supply. Climate change, population growth, and loss of prime agricultural land to development will necessitate judicious use of irrigation water to grow adequate food crops notwithstanding uncertain precipitation levels. The study reported here was conducted at University of Maryland Eastern Shore to determine the influence of deficit irrigation on water use efficiency of corn crop in the 2015 growing season under field conditions using a drip irrigation scheme. Deficit irrigation is being widely investigated as a valuable and sustainable production strategy. It is generally hypothesized that yield loss is less pronounced if irrigation water is available during the reproductive stage of the crop. For this study, the growing season was divided in three equal portions corresponding to early, middle, and late stages of crop growth. Three irrigation treatments were chosen along with a non-irrigated control area. These treatments were based on plant available water in the soil which takes into account the permanent wilting point and field capacity. These treatments were as follows; Treatment 1 (70-70-70), treatment 2 (0-50-50), treatment 3 (0-30-15), and the non-irrigated control (rain-fed). 70 corresponds to maintaining 70% plant available water. It is to be noted two of the treatments have ‘0‘ for the early stage indicating that no irrigation was scheduled. During the growing season weekly measurements were taken using a handheld IRT sensor, soil moisture sensor, as well as a SPAD meter. Thermal imagery was also captured using an unmanned aerial system (UAS). A selected portion of the experimental area was hand harvested and the rest with a combine harvester equipped with a yield monitor. The results of this preliminary field study indicate deficit irrigation does make judicious use of irrigation water. While UAS based thermal image analyses and correlation studies with soil moisture and IRT data holds promise, further investigations will be necessary for conclusive results.