Ginger (Zingiber officinale var. rubrum) is a rhizome plant that can benefit health, fitness and be used as a spice. The content contained in ginger can prevent and treat various diseases and act as an antioxidant and anti-inflammatory agent. The cultivation of ginger plants requires adequate nutrients and water for development and growth. Crop water requirements are influenced by crop coefficients which vary according to the plant growth stage. The crop coefficient values are needed for irrigation management and increasing irrigation efficiency. The main objective of the current study was to investigate the crop coefficient value of ginger by lysimeter. Lysimeter is a water balance device with the principle of mass conservation, where the input is rainfall and irrigation while the output is percolation and evapotranspiration. The rainfall during the investigated period was 0–62.82 mm·day−1, humidity 70.7–89.4%, and air temperature 23.7–32.9 °C. The crop coefficient of ginger increased during the vegetative growth period, i.e., 0.997 in the seedling stage, 1.072 in the tiller stage, and 1.138 in the advanced vegetative stage. The crop coefficient of red ginger was determined using a lysimeter quite accurately, with a coefficient of determination value (R2) 0.950 and a significant value of F less than 0.05.
