Drip irrigation offers excellent method of water and nutrient supply for vegetable crops in precise amounts at a rate, which matches the plant requirements. In addition to allowing precise control of irrigation water applications, drip irrigation system offers the ability to use high frequency fertigation with water soluble N materials throughout the growing season. Little information about optimum fertigation interval for drip-irrigated crops in general and for potato in particular, is available. The present study was conducted to determine the effects of two N rates (200 and 300 kg N ha -1) and four fertigation frequencies (1, 2, 7, and 14 days) on potato yield, N uptake and soil N status in a sandy soil under drip irrigation system. Total potato yield and yield components were responsive to increase N rate and to decrease fertigation frequency. The highest tuber yields (47.16, 46.32 and 44.75 t ha -1) occurred at 300 kg N ha -1 with the frequencies of 1, 2 and 7 days, respectively while yield with the longest interval were significantly lower (37.89 t ha -1). Leaves N concentration at all sampling dates was higher in the plants received high N rate, but fertigation frequency did not significantly affect leaves N concentration except at the longest duration. Similarly, N rate and fertigation frequency resulted in significant differences in total N uptake, N recovery and apparent N use efficiency (NUE). Total N uptake was appreciable higher with increasing N rate and with more frequent than with less frequent fertigation. The averaged N recovery across fertigation frequencies was 68% and 62% and NUE was 151 and 142 kg yield -1 kg N -1 with applied 200 and 300 kg N ha -1, respectively. Analysis of soil samples at the end of last fertigation indicated considerable influence of fertigation frequency on NO 3--N distribution in the root zone of potato. The NO 3--N in lower soil profiles,(40-60 cm) depth with high N rate was marginally affected in daily, alternate and weekly fertigation while NO 3--N in the corresponding soil depth was appreciable higher in biweekly fertigation. Thus, frequent fertigation was needed to obtain maximum yield of potato in sandy soil with less nitrate leaching from root zone.
