Determination of Kolgrace bio-fertilizer rate for optimum greengram (Vigna radiata L. Wilczek) production in Ibadan, Southwest Nigeria

Greengram productivity has been improved by application of farmyard manures in the last two decades; however, these manures are not readily available as at when needed. In some cases, they are available but in limited supply. Kolgrace bio-fertilizer, a novel commercial product of the Association of Organic Agricultural Practitioners could serve as a superior alternative to farmyard manures. Hence, a field experiment was carried out at the Teaching & Research Farm of the Department of Agronomy, University of Ibadan, Nigeria during the 2015 cropping season to evaluate the effects of five rates (0.00, 0.25, 0.50, 1.00, and 2.00 t ha–1) of Kolgrace bio-fertilizer on the performance of greengram. The aim was to determine the optimum rate of application of this biofertilizer for greengram production. The experimental design was a randomized complete block design with four replications. Data were collected on growth and yield traits, and were subjected to analysis of variance. Results showed that Kolgrace rates significantly (p < 0.01) influenced all the traits measured with exception of fresh pod yield (FPY). Plant height (112 cm), number of leaves (87), stem girth (1.43 mm) and number of flowers (10) at 8 weeks after planting (WAP) were significantly highest with the application of 0.5 t ha–1 whereas, 0.25 t ha–1 gave best results for number of pods (42) and pod yield (3.85 t ha –1). The application of 0.5 t ha–1 is, therefore, recommended if the interest of the farmer is sprout, fodder or green manure, and 0.25 t ha–1 if the interest is for seed production.