Time Series Analysis on the Effect of Organic and Inorganic Fertilizer in Production of Teff (Eragrostis tef) in Ethiopia

Abstract

Ethiopia is the only country that produces teff (Eragrostis tef) in the world, but the production of teff is still low compared to other cereal crops. The main purpose of this study was to evaluate the impacts of organic and inorganic fertilizers on teff yield between 1995 and 2017 using an autoregressive distributed lag with co-integration approach. The Phillips Peron test and the Augmented Dickey-Fuller test for time series stationary checking and capturing serial correlation were used, whereas the Breusch Godfrey Lagrange multiplier and the cumulative sum test were used for determining the autocorrelation of residuals and the stability of coefficients. The result showed that the average yield of teff was 11.25 quintals per hectare, and the bounded F-test for cointegration among the variables does not show evidence of a long-run relationship between fertilizers applied and teff yield per hectare. The quantity of urea applied had a positive and significant impact on the yield of teff, and the quantity of di-ammonium phosphate (DAP) application had a negative impact in the short run. In conclusion, there was no co-integration between the yield of teff crops and fertilizer types such as urea and di-ammonium phosphate, which indicates that the quantity of urea fertilizer used for the production of teff has a positive relationship while the quantity of DAP fertilizer had an indirect relationship. Hence inorganic fertilizer like DAP is negatively correlated with the production of teff while organic fertilizer (urea) is positively correlated.