Organic acids content of tubers showed different pattern. Citric acid content of cv. Tenggo increased due to application of K2O fertilizer up to 100 kg ha-1. Increasing fertilizer to 150 kg ha-1 decreased citric acid content. There was no difference in citric acid content between cultivars. Similar patterns was obtained for other organic acids. Increasing fertilizer level to 150 kg ha-1 resulted in decreased organic acids content (Table 4). There were no differences in malic acid content of cv. Tenggo and tartaric acid content of cv. Krespo.