Effect of integrated fertilizer application on soil properties and tef (Eragrostis tef [Zucc] Trotter) yield on Vertisols of Northwestern Ethiopia

Low soil fertility has become a serious constraint affecting agricultural productivity and food security in North-western Ethiopia. A field experiment was conducted to examine the effects of integrated use of compost and mineral fertilizer on soil properties and tef (Eragrostis tef [Zucc.] Trotter) yields for two years during 2018 and 2019 cropping seasons. The field experiment was arranged in a factorial combination of three rates of Urea/NPSB (0/0, 62.5/75 and 125/150 kg ha⁻¹) and three rates of compost (0, 5 and 10 t ha⁻¹) laid out in randomized complete block design (RCBD) with three replications. Results showed that combined use of compost and mineral fertilizer significantly (p < 0.05) increased soil pH, soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), available sulfur (AS) and exchangeable bases but significantly (p < 0.05) decreased soil bulk density (SBD) compared to sole mineral fertilizer application and the control. Furthermore, application of 10 t ha⁻¹ compost combined with 125/150 kg ha⁻¹ Urea/NPSB gave the highest tef dry biomass (8.81 t ha⁻¹) and grain yield (2.40 t ha⁻¹). The economic analysis results also revealed that the highest net benefit (45,761 Birr ha⁻¹) was achieved from the same treatment which was considerably greater than the highest rate of sole mineral fertilizer (37,228.5 Birr ha⁻¹), the highest rate of sole compost (6656 Birr ha⁻¹) and the control (5391 Birr ha⁻¹). We concluded that integrated fertilizer application enhances soil fertility, crop yields and generates better income over individual addition of fertilizers.