THE EFFECT OF VARYING RATES OF NITROGEN AND IRRIGATION ON YAM (DIOSCOREA ALATA L.) PRODUCTION

A series of studies were conducted to evaluate the effects of varying rates of nitrogen fertilizer and applied irrigation, on yam production. Yam was grown in field trials with nitrogen applied at rates of 0, 100, 200 and 300 kg/ha. The application of nitrogen did not affect the production of yam tubers from either of two cultivars ('Binugas' and 'Gunung'). Yields were similar for both cultivars at all nitrogen levels. The results of another study showed that nitrogen applied to 'Gunung' at rates of 0, 50, 100 and 150 kg/ha significantly affected yield and dry matter production. Yam production decreased linearly as nitrogen rates increased. Two trials were conducted to evaluate the effect of varying irrigation rates (rain-fed and soil moisture maintained at 20,40 and 60 kPa) on the production of 'Binugas' yams. The application of irrigation quadratically decreased the dry matter content of the yam tubers, in both trials