Effectiveness of Microdosing in Comparison to Broadcasting and Banding Vermicompost Application for Maize (Zea mays L.) Production in Smallholder Farming of Semiarid Tigray Region of Ethiopia

Optimizing organic fertilizer recommendations can be cost‐effective and affordable for resource‐poor farmers by increasing crop yield and income. This field experiment was conducted to determine the most effective vermicompost application method for enhancing maize production in the Laelay Adiyabo district (Chiraro, Gudelo, and Hibret experimental sites) of Tigray, Ethiopia, during the 2019 growing season. The experiment employed seven treatments: the control, broadcasting of 6 t ha−1 vermicompost, banding of 6 t ha−1 vermicompost, banding of prescribed chemical fertilizer (150 kg NPSZnB ha−1 + 38.5 kg N ha−1), and three treatments of vermicompost microdosing (2, 4, and 6 t ha−1). The treatments were arranged in a randomized complete block design with three replications. Results showed that when plots received prescribed chemical fertilizer of 150 kg NPSZnB ha−1 plus 38.5 kg N ha−1 compared to the control treatment, average stover yields of the experimental sites increased by 81.68% for Chiraro site, 50.38% for Gudelo site, and 65.88% for Hibret site. Microdose application of 6 t ha−1 vermicompost increased stover yield by an average of 66.70% at Chiraro site, 43.44% at Gudelo site, and 62.44% at Hibret site compared to the control treatment. Grain yields increased by 108.37%, 37.16%, and 26.85% at Chiraro site, 97.27%, 57.80%, and 47.69% at Gudelo site, and 104.13%, 75.61%, and 57.99% at Hibret site when plots received the recommended chemical fertilizer of 150 kg NPSZnB ha−1 plus 38.5 kg N ha−1 compared to the control treatment, microdose application of 2 t ha−1 vermicompost and broadcast application of 6 t ha−1 vermicompost, respectively. The microdose application of 6 t ha−1 vermicompost increased grain yield by 88.63%, 24.16%, and 14.83% at Chiraro; 74.18%, 39.33%, and 30.41% at Gudelo; and 61.82%, 39.22%, and 25.25% at Hibret compared to the control treatment, microdose application of 2 t ha−1 vermicompost, and broadcast application of 6 t ha−1 vermicompost. At all study sites, applying the recommended chemical fertilizer of 150 kg NPSZnB ha−1 + 38.5 kg N ha−1 to maize crop plots, followed by microdose application of 6 t ha−1 vermicompost, resulted in improved agronomic yield, maximum net benefits, and marginal rate of returns. Based on the agronomic and economic analysis results, the optimal fertilizer rate for maize production was determined to be 150 kg NPSZnB ha−1 plus 38.5 kg N ha−1. For resource‐poor farmers who cannot afford chemical fertilizers, applying microdoses of 6 t ha−1 vermicompost instead of broadcasting or banded application of 6 t ha−1 vermicompost could be beneficial and used as an alternative to chemical fertilizer for maize production.