Effect of Potassium Fertilizer Dosage on Growth and Yield of Japanese Purple Sweet Potato (Ipomoea batatas Lam.) in Acid Sulphate Soils at Binh Tan District, Vinh Long Province

Abstract

     Potassium is an important nutrient for the growth and root yield of sweet potato. An experiment was carried out to determine the optimal level of potassium for yield and quality of Japanese purple sweet potato in acid sulfate soils at Binh Tan District, Vinh Long Province. The experiment was set up in a randomized completed block design with 7 treatments and 3 replications, 35 m2/each replication (7 x 5 m). The treatments were 100 kg N/ha - 80 kg P₂O₅/ ha combined with 5 levels of K₂O (0, 100, 150, 200 and 250 kg K₂O/ha) and 80 kg P₂O₅/ha - 250 kg K₂O/ha combined with 125 kg N/ha and 187 kg N/ha. The results showed that 200 kg K₂O/ha combined with 100 kg N/ha - 80 kg P₂O₅/ha increased commercial root yield of purple Japanese sweet potato by 57.4% in comparison with zero application of potassium or 31.2% compared with farmers' fertilization practice (100 kg K₂O/ha). It was suggested that growers should apply this as recommendation for sweet potato cultivation in acid sulfate soil at Binh Tan, Vinh Long.