Testing the Efficacy of Deuterium Application for Tracing Water Uptake in Peanuts

Abstract

The ability to determine how long a crop utilizes a given amount of water either from an applied irrigation or from a precipitation event would have great potential in improving irrigation decision systems. However, technical methodologies available to accomplish this measurement are almost entirely unavailable and untested. Experiments were conducted to quantify water movement through soil and peanut plants using deuterium-labeled water applied to simulate a typical irrigation or rainfall event. Soil at four depths and stem tissue samples were collected after the deuterium was applied. The first experiment in Greenville soil was conducted over a 24 h period in order to determine how much water was utilized in a fully charged soil profile. The second experiment in Tifton soil was conducted over a four-day period starting with a relatively dry soil profile in order to determine how long a peanut plant could utilize applied water. Differences in soil water infiltration between overhead irrigation and subsurface drip irrigation were observed, but there was no effect on subsequent peanut water uptake patterns between the two peanut cultivars, Georgia Green and Andru II. The duration of water uptake after a simulated irrigation or precipitation event appears to be between 48 and 72 h for peanut plants. The study demonstrated the utility of applying deuterium-labeled water in order to follow soil infiltration and plant water uptake patterns in a peanut agricultural system.