Search Results
You are looking at 1 - 2 of 2 items for
- Author or Editor: Christine M. Worthington x
The St. Johns River has been identified by the state of Florida as a priority water body in need of restoration. Best Management Practices were evaluated for potato (Solanum tuberosum L. `Atlantic') production in the Tri-County Agricultural Area to reduce nitrate run-off from about 9,300 ha in production. Objectives of this study were 1) determine the influence of soluble and controlled release fertilizer (CRF) and timing of leaching irrigation on nitrate leaching and 2) compare yield and quality of the potato crop fertilized with either a soluble or controlled release nitrogen fertilizer in a seepage irrigated production system. The experiment was a split-split plot with four replications. Main plots were irrigation events (0, 2, 4, 8, and 12 weeks after planting, (WAP)), nitrogen source and rates included (ammonium nitrate (AN) 224 kg·ha–1 or controlled release fertilizer (CRF) 196 kg·ha–1). About 7.6 cm of water was applied at each irrigation event and surface water runoff collected. CRF decreased NO3-N loading by an average of 35%, 28%, and 32% compared to AN fertilizer during the 2, 8, and 12 WAP irrigation events, respectively, compared to AN. Plants in CRF treatments had significantly higher total and marketable tuber yields (30 and 25 t·ha–1) compared to plants in AN treatments (27 and 23 t·ha–1), respectively. Plants in the CRF treatments also had significantly higher total and marketable yields in 2005 (28 and 23 t·ha–1) compared to plants in AN treatments (25 and 21 t·ha–1), respectively. CRF was an effective alternative to conventional soluble forms of fertilizer maintaining yields and protecting natural resources from nonpoint source pollution.
`Atlantic' potatoes (Solanum tuberosum L.) are grown on approximately 8100 hectares with seepage irrigation in Northeast Florida's Tri-County Agricultural Area (St. Johns, Putnam, and Flagler counties). `Atlantic' is preferred for its chipping quality, high specific gravity and yield, but is susceptible to internal heat necrosis (IHN), a physiologic disorder that affects potato tuber quality. The relationships of environmental stressors (growing degree days, GDD and rainfall) to IHN were evaluated on two fields (fields 3 and 4) on a local producer's farm. IHN reduced marketable tuber yield by 100% in the 1995 and 2003 seasons, but not in 2001 and 2002 seasons. From 3 to 6 weeks after planting (WAP), GDD for 1995, 2001, 2002, and 2003 were 470, 325, 386, and 628 (45° F base), respectively. This is the only 4 week period during the 14 week season that GDD accumulation by week was different among treatments. Average rainfalls (cm) for the same periods were 1.60, 1.12, 2.23 and 7.91, respectively. Both warmer/dryer and warmer/wetter early season conditions occurred during seasons with higher rates of IHN. Although circumstantial, higher accumulated heat units and water stress within the first 6 weeks of the growing season resulted in higher percentages of tubers with IHN. These relationships should be evaluated further with other growers.