Response of Teff (Eragrostis tef) to Different Rates of Slow Release and Conventional Urea Fertilizers in Vertisols of Southern Tigray, Ethiopia

Abstract

A field experiment was conducted during the main rainy season of the 2011 at Ofla testing site to determine the optimum rates and overall performance of slow release urea (SRU) fertilizer over conventional urea (CU) fertilizer for teff production. The field experiments comprised of 5 treatments, i.e three rates of slow release urea at 23, 46 and 69kg N ha-1, recommended rate 46kg N ha-1 of conventional urea fertilizer and control (without any N fertilizer) laid down in a randomized complete block design with three replications. All experimental units were supplied with a uniform rate of 46kg P2O5 ha-1 in the form of triple super phosphate (TSP) at planting time. At harvest, the crop was partitioned in to straw and grain for the determinations of N concentrations, uptakes and calculation of N fertilizer recoveries and use efficiencies. Application of different rates and sources of N fertilizer significantly (P≤0.01) affected most the crop parameters tested. The significantly different and maximum plant height (112.33cm ), fertile tillers per plant (22.67), and panicle length (52.00cm ) were obtained from the application of the highest SRU rate (69kg N ha-1) whereas the lowest records were obtained from the control plot of the teff crops. Similarly, the maximum grain yield (3443.67kg ha-1), straw yield (6208.33kg ha-1), total biomass (9652.00kg ha-1) and 1000 grains weight (0.35g) were obtained from the application of the highest SRU rate showing a decreasing trend with declining N rate with the lowest obtained from the control plots of wheat. Application of SRU fertilizer has also affected the grain and straw N contents and uptakes. These showed increasing trend with increasing N rate where the maximum record were obtained at the highest rate of SRU (69kg N ha-1). The application of 46kg N ha-1 of SRU fertilizer has yield advantage of 462.00kg ha-1 over the application of 46kg N ha-1 of CU fertilizer for teff crop. This shows that SRU can reduce N losses by leaching in the form of NO3-, fixation as NH4, volatilization as NH3 and atmospheric emission in the form of N2O or N2. The application of 46kg N ha-1 SRU was the optimum rate.