Effects of nitrogen and potassium rates on growth and yield of red turmeric (Curcuma longa L.) on the gray soil in Ho Chi Minh City

The objective of this study was to determine the appropriate rates of nitrogen and potassium fertilizers for growth, yield and economic efficiency of red turmeric cultivated on the gray soil in Ho Chi Minh City. The field experiment was conducted at the Agronomy Research Station in Nong Lam University, Ho Chi Minh City from December 2020 to October 2021. The experiment was laid out in a split-plot design with three replicates. The main plots included four nitrogen rates 60, 90 (control), 120 and 150 kg N/ha. The subplots included four potassium rates 90, 120 (control), 150, and 180 kg K2O/ha. All treatments were basally applied with 500 kg lime, 10 tons cow manure and 60 kg P2O5/ha. The results showed that growth attributes and yield were significantly affected by the rates of nitrogen and potassium. Red turmeric applied with 150 kg N/ha combined with 180 kg K2O/ha obtained the outstanding results in growth, yield and profit, such as the plant height of 43.0 cm, stem diameter of 19.7 mm, a number of leaves of 8.6 (180 DAP), soil plant analysis development index of 42.1 (120 DAP), actual fresh yield of 33.9 tons/ha, the profit of VND 370.17 million/ha and the benefit-cost ratio of 2.68.