Simple method to determine irrigation water requirement for coffee (Coffea arabica (Linn)) nursery

Easy method that used simple instrument was needed to calculate irrigation water requirement rapidly. The research was conducted to get coefficient for determining crop water requirement. Data was generated with single factor experiment arranged in Randomized Block Design with three replications at Bogor Agricultural University Research Station during March to October 2013. The treatment was five levels of shading that were 0. 25. 50. 75 and 100 % of shading. Coefficient of evapotranspiration was calculated by dividing evapotranpiration value with pan evaporation value. Result of the research showed that shading affected evapotranspiration or crop water requirement. So that. the coefficient of evapotranspiration under different level of shading was also different. Trend line between coefficient of evapotranspiration and leaf number was 0.002 X² + 0.032 X + 1.305 for 0 % of shading. 0.002 X² + 0.009 X + 1.430 for 25 % of shading. 0.007 X² - 0.086 X + 1.676 for 50 % of shading. and 0.002 X² – 0.018 X + 1.311 for 75 % of shading. In conclusion.the coefficient of evapotranspiration under 50% of shading are 1.52. 1.36. 1.20. 1.04 at growth phase of 2. 4. 6 and 8 leaves respectively.