Evaluation of Soil Test Based Phosphorus Fertilizer Recommendations Under Balanced Nutrient Formulations for Teff and Wheat in Southern Ethiopia

Abstract

Nutrient depletion through erosion and removal by crops over many years and limited capacity of farmers to invest in fertilizers or soil conservation measures has resulted in very low productivity.  A trial was conducted to evaluate soil test based fertilizer recommendation under balanced fertilization for teff (Eragrostis tef) and wheat production in the Southern Nations, Nationalities and Peoples’ Region of Ethiopia during the main cropping season of 2015. The treatments were based on soil test based phosphorus (P) fertilizer recommendation of teff (30 kg P ha^-1) and wheat (40 kg P ha^-1). Treatments were arranged in a randomized complete block design and replicated across five farms, including 100% P (30 kg ha^-1) plus recommend N (64 kg ha^-1), 100% P plus balanced fertilizers (NKSZnB), 66 % of P plus balanced fertilizers (NKSZnB), 133 % of P plus balanced fertilizers (NKSZnB) and the agronomic recommendation of  N and P fertilizers (64N + 20P kg ha^-1). The proportion of NKSZnB was 63, 17.5, 7.6, 2.23, 0.37 and 69, 25, 11.2, 3.44, 0.5 kg ha^-1 for teff and whest, respectively. Except number of tillers, grain yield and biomass of teff not showed statistically significant differences (P < 0.05).  Significantly higher number of tillers was recorded when the critical P-value combined with balanced fertilizers (NKSZnB) in both locations at Bensa and Halaba. Similarly, statistical difference (P < 0.05) was observed between treatments on plant height and spike length of wheat.  Although grain and biomass yields of both crops were not showed statistical difference, but in all cases the trend indicated that high results were obtained from plots treated by the soil test based P recommendation plus the balanced fertilizers. The current study indicated that reconsidering the previous soil test based phosphorus fertilizer recommendation under balanced fertilization is required in order to determine P which can be   apposite with the new soil fertility maps of the region (SNNPRS) and nutrient combinations recommended for each woreda.

Keywords: Phosphorus, teff, wheat, use of balanced fertilizers, low productivity