Soil Temperature in the Peanut Pod Zone with Subsurface Drip Irrigation

Abstract

Abstract Maintaining soil temperatures at specified levels (below 29 C) in peanut (Arachis hypogaea L.) is vital to crop growth, development, and pod yield. Subsurface drip irrigation (SDI) systems are not designed to wet the soil surface. Possible lack of moisture in the pod zone could result in elevated soil temperatures that could be detrimental to the peanut crop. The objective of this study was to document the response of pod zone soil temperature when irrigated with a SDI system. Thermocouple sensors were inserted at 5-cm soil depth in the crop row and at specified distances from the crop row in SDI and nonirrigated (NI) treatments. Maximum hourly and daily soil temperature data were measured at three locations, one in Virginia and two in Georgia. The maximum daily soil temperature decreased as plant canopy increased. During the first 50 d after planting (DAP), the average maximum soil temperature was 1 to 2 C cooler for both the SDI and NI treatments than the average maximum air temperature. From 50 DAP to harvest, the average maximum soil temperatures for SDI and NI treatments were 6 C cooler than the average maximum air temperature. During pod filling and maturation, the average maximum soil temperature was about 5 C cooler (27 C) for SDI treatments than the maximum air temperature and 2 C cooler than the recommended 29 C. Soil temperature in the NI treatments did exceed 29 C during periods of drought but decreased to values similar to SDI treatments immediately following a rainfall event. Overall, SDI can maintain maximum soil temperatures below critical values (29 C) during peanut fruit initiation to crop harvest.