Abstract:
Garlic is one of the vegetable crops grown in eastern Ethiopia, but the yield of the crop is low, often constrained by several factors of which the major ones are low soil fertility and poor fertilizer management practices applied. Therefore, this research was undertaken to assess the effects of biochar and NPS fertilizer on yield-related traits and yield of garlic and to estimate the cost-benefit of combined application of biochar and blended NPS fertilizer in garlic production. The experiment was conducted at Raare research field of Haramaya University during the 2022/2023 cropping season. Treatments consisted of four levels of biochar (0, 10, 20, and 30 t ha-1 ) and six levels of NPS fertilizer (0, 50, 100, 150, 200, and 250 kg ha-1 ) laid out in a split plot design where biochar and NPS fertilizer were assigned to main and sub-plots, respectively, and replicated three times. Data were collected on phenology, plant growth, yield component, and bulb yield of Chelenko I garlic variety. Results from analysis of variance revealed significant effects of biochar, NPS fertilizer and the interaction of the two factors on all the measured parameters except the interaction of the two factors had non significant effect on days to 70 % maturity and harvest index (%). The variety had lower mean values for all the measured parameters at control plot but the mean values increased at plots that received biochar and NPS fertilizer. The highest plant height (69.87 cm), average number of leaves (16.2), leaf width (2.16 cm), above ground dry biomass weight (55.65 g), bulb diameter (5.241 cm), bulb length (5.207 cm) and bulb dry matter content (34.9%) were measured at plots that applied 30 t ha-1 biochar and 250 kg ha 1 NPS fertilizer. The highest leaf length (45.4 cm), above ground fresh biomass weight (160.1g), mean bulb weight (54.96 g) and bulb yield (18.32 t ha-1 ) were measured at plots that received 20 t ha-1 biochar and 250 kg ha-1 NPS fertilizer. The mean values for all parameters except mean bulb weight and bulb yield had non significant difference at plots that received 20 and 30 t ha-1 biochar in combination with 250 kg ha-1 NPS fertilizer. The mean bulb weight and bulb yield of the variety had non significant difference at plots that applied 10 and 20 t ha-1 biochar in combination with a 250 kg ha-1 NPS fertilizer. The estimated harvest index (39.63%) was higher due to the application of 30 t ha-1 biochar but had non significant difference with the application of 10 and 20 t ha-1 biochar while it was highest (40.18%) due to the application of 250 kg ha-1 NPS fertilizer. In generally, as the rates of biochar and NPS fertilizer increased the mean values of the measured parameters for the studied variety were also increased. The application of 20 t ha-1 biochar in combination with 250 kg ha-1 NPS fertilizer gave the highest net benefit with acceptable Marginal rate of return (880%). Thus, it is possible to recommend the combined application of 20 t ha-1 biochar and with 250 kg ha-1 NPS fertilizer for the production of the Chelenko I garlic variety at the study area