Nodulation Potential of Annual Sweet Lupins (Lupinus spp. L.) and its Effect on Soil Nitrogen and Phosphorus in Acidic Soils of Western Amhara, Ethiopia

In Ethiopia livestock feed shortage and soil acidity are serious problems. In recent years sweet lupins (white and blue species) were introduced as multipurpose crops in the country. However, there is no information about their nodulation potential. This study was conducted to evaluate nodulation potential of these sweet lupins and their effect on nitrogen (N) and phosphorous (P) content of the soil. Seven lupin varieties were evaluated using factorial arrangement (seven varieties * two inoculations) in a randomized complete block design in two locations for two years. The result showed that effect of inoculation and location was not significant (P > 0.05) on biomass, seed, nodule number and soil parameters. While the effect of variety was significant (P < 0.05) on nodule parameters. Its effect on dry biomass and seed yields was also significant in either of the years. Variety and year had no effect on soil N and P contents. In the first year, blue sweet lupin entries had the highest nodule number per plant, 222 nodules.  In the second year similar nodulation performance was observed among species and varieties. Soil N and P were not affected by varieties and inoculation. In addition to their yield advantage, compared to the sweet white entries, blue sweet lupin varieties had high potential in nodulation. Therefore, these introduced sweet blue lupins can be used as multipurpose crops in acidic soils of Ethiopia.