NITROGEN RATE AND WITHIN-ROW PLANT SPACING EFFECTS ON SWEET-POTATO YIELD AND GRADE

A 2-yr study was conducted to evaluate the effect of within-row spacin g and nitrogen (N) fertility on sweetpotato [Ipomoea batatas (L.) Lam. ] yield and quality. Conducted in North Alabama on a Hartsells fine sa ndy loam (fine-loamy, siliceous, thermic Typic Hapludult), the study c onsisted of four replications of a factorial arrangement of four withi n-row spacings (15, 20, 25, and 30 cm) and 4 N fertility rates (0, 36, 72, and 108 kg N/ha). Nitrogen fertilization did not affect yield or quality of harvested storage roots and there was no significant intera ction between row spacing and N rate in either year. In 1994, greatest total yield of sweetpotatoes occurred with the narrowest within-row s pacing (15 cm), but in 1995 within-row spacing did not affect total yi eld. In 1994, as within-row spacing increased, yield of Jumbo sweetpot atoes increased.