Optimal fertiliser dose and nutrients allocation in local and biofortified bean varieties grown on ferralsols in eastern Democratic Republic of the Congo

Abstract

Low crop yields are observed in the soils of South Kivu and lead to food insecurity and malnutrition. An experiment was conducted on a ferralsol to determine the optimal dose in both local and improved common bean cultivars (M’Sole and HM-21) and subsequently that which will allow store nutrients not only in the leaves but also in the seeds, the two parts of the plant commonly consumed and sold in the region. Experiments were conducted in a split-plot design with three replications in 2017 and 2018. Observations were focused on growth and yield parameters. N, P, and Fe levels were determined in leaves, roots and seeds. Results showed that common bean yield and its related parameters were influenced by the fertilizer doses and varieties. The biofortified variety (HM-21) presented higher yield than the local (M’Sole). The allocation of N, P and Fe varied from one variety to another; the best concentration was obtained with 51 kg ha−1 of N, P and K which corresponded to 300 kg ha−1 of NPK composite fertiliser. High nutrient concentrations were observed in young (0.23 g kg−1 of N and 51 ppm of Fe), actively growing leaves (0.19 g kg−1 of N and 50 ppm of Fe) and at the end of the growth cycle (0.19 g kg−1 of N and 48 ppm Fe). Thus, grains and leaves of biofortified beans can reduce anemia problems in eastern of DR Congo by increasing yield and nutrient concentrations in grains and leaves by using 300 kg ha−1 on degraded ferralsols of South-Kivu, eastern of DR Congo.