A field experiment was conducted for three years to determine the economic optimum rate of NPSZnB blended + urea fertilisers for upland rice production in Fogera and Libokemkem districts of the Amhara Region. Blended NPSZnB fertiliser rates of 100, 150, 200 and 250 kg ha⁻¹ were factorially combined with 100, 150, 200 and 250 kg urea ha⁻¹.. Zero fertiliser as a control treatment and recommended NP fertiliser as a reference treatment were included in the study. The treatments were laid in a randomised complete block design with three replications. The results indicated that the highest grain yields of 4 and 6 t ha⁻¹ at Libokemikem and Fogera districts, respectively, were obtained from 250 kg NPSZnB + 200 kg urea ha⁻¹.. The highest biomass yields at both districts were obtained from 250 kg NPSZnB + 250 kg urea ha⁻¹.. The partial budget analysis of the pooled data indicates that, in the Libokemikem district, the maximum net economic return (NER) of Ethiopian Birr (Birr) 37,474.80 with a marginal rate return (MRR) of 2617.5% was obtained from 250 kg NPSZnB + 200 kg urea ha⁻¹.. At Fogera district the maximum NER of Birr 62,548.60 with MRR 1214.6% was obtained from 100 kg NPSZnB + 250 kg urea ha⁻¹.. However, it is not possible to draw conclusions that the significant yield increment recorded was due to the contribution of S, B and Zn blends in the NPSB blended fertiliser. Because there were confounding effects of N and P nutrients in the NPSZnB blended fertiliser. As it is revealed in the results, the significant yield response recorded, however, was due to the increasing levels of N. Therefore, we recommend further investigation of the response of NERICA-4 (upland rice) to each nutrient (P, S, Zn and B) through nutrient omission studies.
Keywords: upland rice, Blended, NPSZnB and Partial budget