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

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. Sweet potato is potential crop developed in dryland regions, yet the yield is deemed low due to poor soil conditions. Thus, fertilizers are often needed to improve soil quality, leading to increasing tuber yield. 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 sweet potato. 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 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.