The effect of cattle manure and mineral fertilizers on soil chemical properties and tuber yield of purple-fleshed sweet potato in the dryland region of East Nusa Tenggara, Indonesia

Abstract. Nur MSM, Arsa IGBA, Malaipada Y. 2019. The effect of cattle manure and mineral fertilizers on soil chemical properties and tuber yield of purple-fleshed sweet potato in the dryland region of East Nusa Tenggara, Indonesia. Trop Drylands 3: 56-59. A field experiment was carried out to study the effect of combination of cattle manure and mineral fertilizer on the soil chemical properties and yield of purple-fleshed sweet potato in the Integrated Field Laboratory of Archipelagic Dryland Center of Excellence, Universitas Nusa Cendana during November 2017 to March 2018. The experiment was arranged in a Randomized Block Design, with six treatments and four replicates. The assigned treatments were P0 = without manure and without mineral fertilizer, P1 = 100% recommended dosage of manure (20 tons ha-1), P2 = 75% recommended dosage of manure (15 tons ha-1) + 25% recommended dosage of mineral fertilizer (25 kg urea ha-1, 25 kg SP-36 ha-1 and 37.5 kg KCl ha-1), P3 = 50% recommended dosage of manure (10 tons ha-1) + 50% recommended dosage of mineral fertilizer (50 kg urea ha-1, 50 kg SP-36 ha-1 and 75 kg KCl ha-1), P4 = 25% recommended dosage of manure (5 tons ha-1) + 75% recommended dosage of mineral fertilizer (75 kg urea ha-1, 75 kg SP-36 ha-1 and 112.5 kg KCl ha-1), and P5 = 100% recommended dosage of mineral fertilizer (100 kg urea ha-1, 100 kg SP-36 ha-1, 150 kg KCl ha-1). The results showed that P1 and P2 treatments produced the highest contents of organic-C, total-N, available-P, exchangeable-K and soil Cation Exchange Capacity. However, the highest tuber weight was obtained in the treatment P3. These results indicated that the combination of 50% recommended manure dosage (10 tons ha-1) + 50% recommended mineral fertilizer dosage (50 kg urea ha-1, 50 kg SP-36 ha-1 and 75 kg KCl ha-1) could provide a balanced nutrient content in sufficient quantities that meet the sweet potato requirements from the early growth stage to the tuber formation stage, and create soil physical conditions that support the sweet potato tuber development.