Integrated mineral fertilizer and vermicompost effects on soil health and inulin of Jerusalem artichoke genotypes under a tropical savanna climate

Using vermicompost as fertilizer could be an alternative strategy for desirable production of Jerusalem artichoke (Helianthus tuberosus L.) and soil health. This research aims to determine the effects of vermicompost combined with mineral fertilizer on the soil properties, growth, yield, and inulin content of different Jerusalem artichoke genotypes. Inulin is important as a prebiotic and low-calorie food ingredient used in the food and pharmaceutical industries. Field experiments were conducted in Khon Kaen and Nakhon Phanom Provinces, Thailand. The experiment employed a split–plot in a randomized complete block design (RCBD) with three replications. Five fertilizer treatments were assigned to main plots and four genotypes (lines) to sub plots. Data were recorded for weather, soil properties, crop dry weight. Inulin contents were measured by using a spectrophotometer. The crop and soil data were separately analyzed for each location. Integrating vermicompost at a rate of 12.5 ton ha⁻¹ with half the recommended mineral fertilizer significantly improved soil organic matter, total nitrogen, available phosphorus, and extractable potassium. This treatment provided high biomass partitioning to below–ground organs, inulin accumulation, and tuber dry weight. Among the tested genotypes, (CN 52867 × JA 6)–23 in Khon Kaen and (JA37 × HEL 65)–16 in Nakhon Phanom demonstrated superior inulin content, while (CN 52867 × JA 6)–23 in Khon Kaen (+ 26% over the lowest genotype, 11.26 ton ha–1) and (JA37 × HEL 65)–16 in Nakhon Phanom (+ 34% over the lowest genotype, 7.67 ton ha–1) achieved the highest tuber dry weight as compared to the other genotypes. This study showed that, to improve yield and quality of Jerusalem artichoke while promoting soil-friendly production, farmers are recommended to use a superior combination of vermicompost and mineral fertilizer along with desirable genotypes.