Simulating development, biomass and yield of tef (Quncho variety) using FAO’s AquaCrop model: a case study in Mekelle area

The experiment was carried out in the northern Ethiopia at Mekelle University Main campus in 2012. The objectives were to evaluate the effect of fertilizer and water level on yield and yield component as well as to simulate, development, biomass and yield of improved tef (Quncho) variety under different levels of water and fertilizer. The experimental design was arranged in a Randomized Completely Block Design (RBCD) in two factorial with fertilizer treatments of 0, 32 and 64 kg.ha-1 of N; and 0, 23, 46 kg.ha-1 of P in N-P combinations, respectively; and water treatments: deficit irrigation(two irrigation and four irrigation) and full irrigation (nine irrigation) after cessation of rainfall and rainfed (control). The experimental crop was sown by broadcasting at a seeding rate of 25kg.ha-1 and the plot size was 4 mx3 m. The highest (LAI=4.77) was recorded for high fertilizer treatment N-P combination (with 64 kg.ha-1N and 46 kg.ha-1P with deficit irrigation (four irrigation) after the cessation of rainfall whereas the lowest (LAI=2.27) was recorded for zero fertilizer treatment (zero NP kg.ha-1) under rainfed condition. Results showed that the highest leaf area index (LAI=4.77) was recorded between 63 and 73 after sowing (DAS) for all treatments. The result of the research showed that the highest aboveground biomass (10416.7 kg. ha-1) and grain yield (2190.8 kg. ha-1) were obtained from treatments that received relatively high fertilizer (64 kg.ha-1N and 46 kg.ha-1 P) with full irrigation (nine irrigation) whereas the lowest aboveground biomass (4375 kg. ha-1) and grain yield (1008.1 kg. ha-1) were obtained from treatments that received zero NP kg ha-1under rainfed condition. During the experiment the water productivity of tef was 30 g.m-2. The model efficiency (ME) values for canopy cover (CC) simulation over the growing season were between 0.94 and 0.98 whereas the root mean square of error (RMSE) for CC ranged between 1.72 and 2.67%. The simulated tef grain yield deviated from the observed value with a range of -20.92% to 10.21%. Similarly, the model efficiency (ME) for grain yield and biomass simulation was 0.81 and 0.74, respectively. The root mean square error (RMSE) for grain yield and aboveground biomass were 0.77 and 0.18 t ha-1, respectively. Therefore, the result of this research showed that AquaCrop model was able to adequately simulate the canopy cover, development, aboveground biomass and grain yield of tef under different irrigation managements.