8Larry K H, Conrad H M, William H S, et al. Influence of N source, N rate and K rate on the yield and mineral concentration ofsweetpotato[J].J. Am. Soc. Hort. Sci.,1984,109(3): 294 - 298.
9Bourke R M. Influence of nitrogen and potassium fertilizer on growth of sweet potato (Ipomoea Batatas ) in Papua New Guinea[ J ]. Field Crops Research, 1985,12:363 - 375.
10Nicholaides J J,Chancy H F,Mascagni H J,et al. Sweet potato response to K and P fertilization [J]. Agron. J. ,1985,77:466 - 470.