Potato (solarium tuberosum l.) yield and internal heat necrosis incidence under controlled-release and soluble nitrogen sources and leaching irrigation events

Abstract

Best management practices (BMPs) have been developed for northeast Florida potato production with the objective of reducing N fertilizer use while main-taining tuber yield and quality. However, rainfall timing and intensity can affect soil N availability, tuber yield, and quality. Objectives of this study were to determine the influence of fertilizer source (soluble and controlled-release) and timing of leaching irrigation on tuber yield and quality of ‘Atlantic’ potato in a seepage-irrigated production system. The experiment was conducted in 2004 and 2005 as a split-split plot with four replications. Main effects were leaching irrigation treatments (no-leaching irrigation and leaching irrigation at 2, 4, 8 and 12 weeks after planting [WAP]), N source (ammonium nitrate [AN] at 224 kg ha-1 or controlled-release fertilizer [CRF] at 196 kg ha-1), and supplemental N sidedress application (34 kg N ha-1). In 2004, total and marketable tuber yields for plants in the 8 and 12 WAP leaching treatments were 10% and 11% lower, respectively, than plants in the no-leaching treatment. In 2005, marketable tuber yields from plants in the no-leaching treatment were significantly higher than plants in the 4, 8 and 12 WAP leaching treatments. Plants in CRF treatments produced significantly higher marketable tuber yields in both years compared with plants in AN fertilizer treatments. Supplemental N sidedressing did not improve tuber yield or quality in either year. Plants in the CRF treatment had a higher incidence of tubers with internal heat necrosis (IHN) in 2004 and 2005 compared with plants in the AN fertilizer treat-ment. This suggests that under severe leaching pres-sures, CRF needs a faster soil nutrient “recharge” to reduce plant nutrient stress. Plants in the CRF treatment averaged 12% higher marketable tuber yields with 13% less N applied compared with the AN treatment. Overall, CRFs are well suited as a BMP for northeast Florida potato production.