Using Gliricidia sepium prunings as green manure in a degraded ultisol ; effect on soil physical properties and yield of okra ( Abelmuschus esculentus ) in Abakaliki, southeast Nigeria

Okra (Abelmoschus esculentus) is an important vegetable crop in southeast Nigeria, though at present there are only limited data available on the production in this area. A two-year field experiment was carried out in 2019 and 2020 cropping seasons to determine the effects of soil incorporation of different rates of Gliricidia sepium prunings (GS) as a green manure on soil consistency limits and physical properties, and yield of okra. The experiment was arranged as a randomised complete block design with four treatments and five replications. The treatments were as follows: control (C, no amendment); application of GS at 3 t ha−1 (3 GS), GS at 6 t ha−1 (6 GS); and GS at 8 t ha−1 (8 GS). The results showed significant increases (p < 0.05) in soil consistency limits in soil amended with GS relative to the control. The result also showed significant decrease in soil bulk density and increase in total porosity in soil amended with GS green manure. Soil water retention was significantly higher in Gliricidia sepium–amended plots. The dry pod yield of the okra increased significantly with the incorporation of the Gliricidia sepium green manure, though the differences in the yield between treatments with 6 and 8 t ha−1 rates of incorporation were not significant. Using GS as a green manure improved the consistency limits and physical properties of the soil and resulted in enhanced okra yields.