Response of Sweetpotato to An Organic Fish Protein-Based Organic Fertilizer and Composted Broiler Litter

Field experiments were conducted in 2008 and 2009 to evaluate the influence of an organic fish protein based fertilizer and broiler litter on storage root yield and leaf N elemental concentration of   3 sweetpotato cultivars.  Treatments were fish protein-based organic fertilizer (FPP), composted broiler litter (BL), and NPK.  Broiler litter was applied at the rate of 134 kg/ha and N P K based at the rate of 134, 67 and 67 kg/ha, respectively, based on soil test.  The FPP was applied following manufacturer’s recommendation of 30 g/L weekly.  Pre-rooted stem cuttings of ‘Whatley/Loretan’, NCC-58, and J6/66 were transplanted to the field and grown for 120 days.  Leaf samples were collected at 4 and 8 weeks after planting and composited, for elemental analysis. Total root and US#1 yield for ‘Whatley/Loretan’ were higher for plants receiving fertilizer followed by FPP and BL, that for NCC-58 and J6/66 were higher with FPP, BL and fertilizer, respectively.  Leaf N exceeded 3.2 % for all treatments except that for BL which was marginally lower.  These results suggest that sweetpotato response to FPP was cultivar dependent and that FPP could be a suitable source of nutrients for sweetpotato production in an organic production system.