Subsurface Drip Irrigation Affects Water Usage and Yield in Acorn Squash

Subsurface drip irrigation (SDI) has been successfully utilized for the production of processing tomatoes. It allows for efficient water use as well as a reduction of in-row weed growth due to a reduced wetting of the soil surface. However, significantly less is known about the impact of SDI on growth of vegetables in the humid southeastern United States.  To evaluate the suitability of SDI for vegetable production, a two-year trial was conducted to determine the effects of SDI on water use efficiency as well as productivity of acorn squash (Cucurbita pepo) grown in Lexington, KY.  Six-week-old plants of acorn squash, ‘Table Queen’, were transplanted in July and June of 2011 and 2012, respectively, into bare-ground plots with surface and SDI. The SDI drip tubing was placed at a depth of 15 cm below the soil surface. In addition to irrigation type, 2 moisture regimes were evaluated using automated tensiometers for irrigation. Irrigation levels were on/off –30/–10 kPa and –60/–10 kPa, representing well-watered and relatively dry irrigation regimes, respectively.  The trial was  2 x 2 factorial arranged in a completely randomized design. In 2011, SDI irrigation regimes used significantly less water than the comparable surface irrigation treatments, while achieving higher yields. In 2012, however, yields were significantly higher in the –30/–10 kPa surface irrigation treatment than all other treatments.  In 2012 the –30/–10 kPa irrigation treatment irrigated frequently, but for a relatively shorter period of time than other treatments and used about 17% less water than the comparable SDI treatment. Water use was significantly greater in the SDI treatments than in the comparable surface treatments in 2012. There were no quality differences in fruit among the irrigation treatments in either year. It was noteworthy that the growing season in 2012 was significantly warmer with less rainfall than in 2011, suggesting that weather conditions could influence the response of a crop to irrigation method. Results suggest that SDI may provide some benefits over traditional surface applied drip irrigation, but that climate can also significantly interact with irrigation method.