The Effect of Eliminating the Application of Phosphorus-Containing Fertilizer for the Bulking Period of Sweet Potato (Ipomoea batatas) Production

The Philippine Root Crop Research and Training Center (PhilRootcrops) divided fertilizer applications for sweet potato farming into various phases. Full fertilizer is applied two weeks after planting for the vegetative growth period. Apply another set of fertilizers containing a combination of nitrogen and potassium during the bulking period one and a half months later; this is one way to give the tuber a sweetened flavor. Because fresh sweet potato tubers are more marketable if their sizes are more or less consistent, the study hypothesized that ceasing to apply fertilizer containing phosphorus will adversely affect the uniformity of the size of sweet potato tubers. The application of mixtures of muriate of potash and urea-containing fertilizer increased sweet potato tubers with the highest average circumference and the average weight in Treatment 2 [Circumference (C)=12.4 cm; weight (W)=0.35 kg], which demonstrates the elimination of phosphorus-containing fertilizer for the bulking period of sweet potato production. According to the one-way analysis of variance (ANOVA) and F test (F = 1.09, p = 0.41), there was no statistically significant difference in the dependent variable between the various groups. The study finds that using muriate of potash and urea-containing fertilizer combinations generated the maximum yield in terms of circumference and weight per tuber for sweet potato farming with semi-loam varieties (Treatment 2). The usual application of the farmers under study to Treatment 2 is to reduce the use of synthetic fertilizers. Based on the study results, phosphorus-containing fertilizer does not affect sweet potato tuber yield.