The 2012 ASHS Annual Conference

Potatoes are the leading vegetable crop in the United States, contributing to about 15% of farm sales receipts. In 2010 the Florida potato was valued at $135 million, ranking Florida 11^th in total value and producing one-third of winter/spring crop season. Seepage (sub-surface) irrigation is the predominant irrigation method for potato production in the state. Although inexpensive, it has a low irrigation efficiency (<50%) and requires a large volume of water to maintain the high water table. Irrigation techniques with higher delivery efficiency, such as drip, have the potential to save water with application directly to the root zone, and increase the potential to reduce N-leaching. The objective of this 2-year field study was to assess the feasibility of drip irrigation as alternative irrigation method for potato production in Florida sandy soils. Field experiments were  conducted during spring of 2011 and 2012 in Hastings, FL. The design was a split plot with irrigation treatment as a whole-plot in a randomized complete-block with 4 replicates; potato varieties were applied to sub-plots. Irrigation treatments included: SUR-surface drip irrigation with drip installed above seed; SUB-subsurface-drip irrigation with drip tape installed below 5-cm the seed; and SEP seepage. The potato varieties were ‘Atlantic’, ‘Fabula’, and ‘Red LaSoda’. The average daily irrigation volume applied using drip was 3.8 mm, while seepage required application on the order of 15.5 mm/day to maintain the high water table. There was an interaction between irrigation and variety treatments for  marketable yield For ‘Atlantic’ and ‘Fabula’, there was no marketable yield difference between SUR and SEP irrigation; the varieties yielded 24.8 and 15.9 Mg/ha, respectively. The use of SUB resulted in reduced yield by 20% and 25% for ‘Atlantic’ and ‘Fabula’, respectively. On the contrary, marketable yield of ‘Red LaSoda’ was 51% and 37% higher when SEP (26.0 Mg/ha) was used compared to SUR and SUB, respectively. Low yields of ‘Red LaSoda’ under SUR and SUB treatments indicated that alternative irrigation scheduling needs to be investigated for this variety. Drip irrigation positively affected tuber internal quality, as SUR and SUB showed lower incidence of growth cracks, misshapen and brown center for all tested varieties, and reduced internal heat necrosis for ‘Atlantic’. It is concluded that appropriate use of SUR can sustain profitable yields for ‘Atlantic’ and ‘Fabula’ varieties while saving irrigation water in soils with low water-holding capacity.