Response of N-Fertilizer Rates and Water Table Irrigation Management On Yield of Chipping Potatoes in Florida.

Seepage irrigation, also classified as subirrigation, requires significant water withdrawals from the aquifer to maintain a high water table to irrigate the crop. High water table level facilitates offsite movement of soluble nutrients and runoff. Because seepage relies on capillarity movement of soil water from the water table up to the plant roots, determination of the adequate water table level is fundamental achieve ideal soil moisture at the root zone. The objective of this study is to determine yield and fertilizer use efficiency of potato in response N-fertilizer rates under three water table levels. Field experiments were conducted in Hastings, FL. The experimental design was split-plot, evaluating N-rates at 0, 112, 224, 336 kg ha^-1 with variety as the split-plot factor (‘Atlantic’ and ‘FL1867’). Each treatment was replicated three times in each of three adjacent potato fields, for a total of nine replications. The three fields were controlled to maintain a different water table height, targeting 40, 55, and 75 cm below the top of the raised potato row and root zone soil moisture was used as a covariate factor for each replicate. The effects of N-rate, variety, and soil moisture on soil nitrogen levels, plant biomass, plant nitrogen content, and potato yield were quantified. Soil mineral nitrogen content at 0-15 cm throughout the season was influenced by both N-rate and soil moisture (p<0.01). Marketable yield ranged from 0.3 to 34.0 Mg ha^-1 and was impacted by potato variety (p=0.02). 'FL1867' yielded 1.3 Mg ha^-1 higher on average than Atlantic. Treatments receiving above 224 kg ha^-1 N had the highest yield, with high  soil moisture impacting marketable yield at all N-rates (α=0.05)  The results of this study suggest that water table management in conjunction with N-rate are necessary to ensure optimized potato growth, yield and potato quality.