EFFECTS OF IPIL-IPIL AND AMMONIUM SULFATE AS NITROGEN SOURCES OF SWEET POTATO

Abstract

Nitrogen application, either with the use of ammonium sulfate or ipil-ipil leaves, significantly improved the yield and yield components of the three varieties of sweet potato, except in the number of non-marketable tubers. Among the varieties tested, BNAS-51 yielded the highest amount of marketable tubers with an average of 11.7 t/ha, followed by Bakabakahan and Bulacan with 8.03 and 6.6 t/ha, respectively. BNAS-51 and Bakabakahan produced more and heavier marketable tubers/plant, and longer and heavier fresh weight of vines/plant. BNAS-51 had fewer but heavier non-marketable tubers than the other two varieties. Plants which received nitrogen (N) from ipil-ipil leaves produced more and heavier fresh vines/plant than those without N. A lower percentage of dry matter content was observed in N-fertilized plants. In terms of tuber yield, plants which received 60 kg/ha, either from ipil-ipil leaves or ammonium sulfate, yielded more with 3.0 and 6.0 t/ha, respectively, than those plants which did not receive N. Despite the equal rates of N application, plants which were applied with inorganic N fertilizer (ammonium sulfate) produced significantly higher yields than plants which received organic fertilizer (ipil-ipil leaves).