Previous PageTable Of ContentsNext Page




Summary

This report describes an approach to assess locations and areal expanses that have potential for the production of bambara groundnut (Vigna subterranea L. Verdc) across the world. The methodology was applied both to regions such as Africa, where the crop is widely cultivated but where experimental evidence is limited, and to new regions that have not previously been associated with bambara groundnut but where environmental factors are conducive for productive growth. A weather generator and a crop simulation model of bambara groundnut (BAMnut) were incorporated into a Geographical Information System (GIS) to predict, for the first time, bambara groundnut production for the world.

A gridded mean monthly climate dataset at a resolution of 50 km x 50 km for global land areas (excluding Antarctica), for the period 1961-1990, were used as input to the weather data generator to generate daily weather data. Simulation results from BAMnut in a suitable format were used as input to the GIS to provide the required maps and statistics. Given the time frame of the present study, neither the model nor the overall methodology attempted to account for the specific effects of soil type, pests or diseases on the likely productivity of bambara groundnut at any location. Similarly, the influence of daylength sensitivity for pod filling in many bambara groundnut landraces was not assessed in relation to potential yield. However, by scrutinising the world for bambara groundnut potential in relatively small sites, GIS technology provided a means to ask, "where is the best potential for growth, what is the likely yield threshold and over how much surface area of land are yields achievable"?

Each site that was evaluated was approximately a 50 km x 50 km (at the equator) grid cell, of which 62,482 cells corresponded to global land areas. Results show that bambara groundnut is likely to produce significant pod yields in many parts of the world beyond its current distribution with suitable areas of potential production in America, Australia, Europe and Asia as well as Africa. In fact, locations within the Mediterranean region show the highest predicted biomass, often exceeding 8.5 t ha-1. The mapped predictions indicate that the productivity of bambara groundnut is likely to be influenced by the pattern of rainfall distribution as well as its annual amount and by the minimum and maximum temperature during the growing season. When factors such as the seasonal distribution of rainfall, daylength and range of temperatures during the growing season are accounted for, the potential yields of bambara groundnut within its current areas of cultivation can be significantly increased without high levels of agronomic inputs.

The preliminary identification of potentially suitable areas for production, based on the agro-ecological requirements of the crop, serve as a useful prelude to detailed field investigations on bambara groundnut to identify appropriate management practices and may provide a basis for a similar assessment on many other underutilised crops. The approach described here has implications for issues of food security since the methodology can be rapidly extended to assess the potential productivity of many subsistence food crops that contribute to the diets of the world's poorest people.




Previous PageTop Of PageNext Page