Abstract

Study was carried out to evaluate the supplementary nitrogen requirement of tef to enhance nitrogen use efficiency of tef grown under chickpea-tef rotation cropping. On-farm, experiment was conducted during the 2015 main cropping season at Tahtay Koraro District of the Tigray regional State, Ethiopia on tef after preceding chickpea. The experiment was set in a randomized complete block design with three replications. Seven treatments: Six N levels (0, 11.5, 23, 34.5, 46, and 69 kg N ha-1) under the chickpea-tef rotation and the seventh one negative control (0 kg N ha-1) under the continuous tef cropping were tested. Surface soil samples were collected before tef sowing and after harvesting. They were analyzed for selected soil properties. Clay sized particles dominate the soil of the experimental site and the textural class of the soil is clayey. There was a difference in the bulk density of the same soil between the chickpea-tef and tef-tef sequence. Nitrogen and organic carbon were higher in soil under chickpea-tef cropping sequence than in soil under continuous tef cropping. Application of different N rates under chickpea-tef rotation statistically significantly affected grain (GNU), straw (SNU) and total nitrogen uptake (TNU) (kg ha-1). The highest total tef nitrogen uptake (59 kg N ha-1) was obtained in response to application of 34.5 kg N ha-1. The highest apparent nitrogen recovery (81%), agronomic efficiency (10.48 kg kg-1) and physiological N use efficiency were obtained in response to the lower N rate (11.5 kg N ha-1), 23 kg N ha-1 rate and 34.5 kg N ha-1 respectively. The highest grain protein content (7.78%) was recorded for grain harvested from plots fertilized with 23 kg N ha-1. Hence, it could be concluded that, under chickpea-tef rotation cropping system some supplementary nitrogen is needed to fulfill the nitrogen requirement and nitrogen use efficiency of tef crop at the study area.

Key words: Chickpea, tef, nitrogen uptake, nitrogen use efficiency, protein content.