Influence of integrated soil fertilization on the productivity and economic return of garlic (Allium sativum L.) and soil fertility in northwest Ethiopian highlands

Abstract

Abstract Garlic (Allium sativum L.) is one of the main economical spices produced by poor smallholder farmers in the highlands of Ethiopia for both marketing and consumption. However, its productivity in the area has ever been declining mainly due to soil fertility depletion. Hence, an experiment was conducted under irrigation for two years in 2017 and 2018 in one of northwest Ethiopian highlands known as Lay Gayint to assess the productivity response of garlic to NPS inorganic fertilizers and cattle manure applications. Factorial combinations of four levels of N–P2O5–S inorganic fertilizers (0–0–0; 70–21–9; 112–37–16; and 159–58–25 kg ha−1) and four levels of fresh cattle manure (0, 5, 10, and 15 t ha−1) were laid out in randomized complete block design with three replications. Unlike that of NPS inorganic fertilizers application and its interaction with cattle manure, physicochemical properties of the experimental soil were highly significantly improved with cattle manure application. Most growth and bulb yield parameters of garlic were significantly influenced by combined applications of NPS inorganic fertilizers and cattle manure, and their responses were more pronounced with the progress of the cropping seasons. Combined applications of 112–37–16 kg ha−1 N–P2O5–S inorganic fertilizers with 15 and 10 t ha−1 cattle manure gave the highest bulb yields (18.03–22.05  t ha−1), net benefits (Ethiopian Birr 509,456–626,814 per hectare), and marginal rate of returns (1,492.35–2,005.15%) in both study years of 2017 and 2018. Hence, combined applications of 112–37–16 kg ha−1 N–P2O5–S inorganic fertilizers with 10–15  t ha−1 cattle manure are recommendable for garlic growing farmers in northwest Ethiopian highlands.