Response of Soil Chemical Properties under Tef (Eragrostis tef (Zucc.) Trotter) Field to Integrated Application of Lantana camara L. Weed Vermicompost and NPS Mineral Fertilizer

Recently, the beauty of the environment, native forest plants, and crops were encroached with invasive weeds, and thus scientific community was concerned with searching for optional management of these horrible weeds. Accordingly, vermicomposting of invasive weeds with the purpose of utilization management was evaluated as an alternative option and cost-effective management. Utilization management included keeping the environment safe from expanding invasive weeds by using these weeds as vermicomposting materials. Consequently, vermicompost was produced from L. camara invasive weed and this produced vermicompost was interactively used with chemical fertilizer to appraise its effect on soil chemical properties after the tef crop was harvested. The experiment was arranged in a randomized complete block design (RCBD) in a factorial combination with three replications. Four levels of L. camara vermicompost amendment (0, 2, 4, and 6 t·ha−1) and four levels of NPS fertilizer (0, 100, 150, and 200 kg·ha−1) were used in the combination of the treatments. Disturbed composite soil sampling at a depth of 20 cm was carried out, one sample before planting and 48 samples after harvesting of the tef crop. The results showed that the combined addition of vermicompost and NPS fertilizers at the rate of 6 t·ha−1 and 200 kg·ha−1, respectively, significantly increased plant-available phosphorus (Av. P). Reversely, the pH of the soil remained unchanged when the soil was treated with the integration of vermicompost and NPS fertilizer or at their separate individual application. Most of the soil chemical properties, i.e. soil organic carbon (SOC), electrical conductivity (EC), Av. P, total nitrogen (TN), carbon-to-nitrogen ratio (C : N), and cation exchange capacity (CEC) were found to be improved when the soil was amended with the highest dose of sole L. camara vermicompost fertilizer. The two-year consecutive organic fertilizer fertilization rate increased SOC from 63.64% to 107.56%, EC from 8.70% to 22.22%, Av. P from 40.87% to 143.13%, TN from 50% to 100%, C : N ratio from 8.14% to 11.58%, and CEC from 42.11% to 63.67% versus untreated plot. Single-application NPS chemical fertilizer has only an encouraging effect on Av. P and CEC of soil. The principal driving factor for any change in soil chemical properties was the L. camara vermicompost amendment. Therefore, using L. camara weed as a vermicompost can enhance soil fertility. This study offers the opportunity to convert the large biomass of L. camara weed into vermicompost through vermicomposting.