Soil fertility maintenance with organic amendments to orange fleshed sweetpotato
Smallholders in sub-Saharan Africa traditionally cultivate orange-fleshed sweetpotato without soil fertility management, leading to soil nutrient mining and thereby threatening future food security. We set out to determine the potential of locally-accessible organic amendments and weed biomass management to secure crop nutritional quality and yield while maintaining soil fertility. Orange-fleshed sweet potato was fertilized with sole or co-application of poultry manure, cowpea residue, and inorganic fertilizer, combined with removal or incorporation of biomass residue from the fallow period. Non-amended control represented current farmers practice. Poultry manure fertilization, in sole or co-application with inorganic fertilizer, maintained storage root yield from the first to the second season, averaging 7.7 t ha−1. Conversely, non-amended control decreased storage root yield by 61% from the first to the second season. Poultry manure with weed biomass incorporation maintained total soil C and N at 14.4 g kg−1 and 1.1 g kg−1, respectively, after two growing seasons. Poultry manure co-applied with inorganic fertilizer decreased total C and N by 15% and 14% respectively. The changes in soil total C and N observed in this experiment provide basis to support management recommendations for farmers focusing on locally-sourced organic amendments. Poultry manure is the more reliable organic amendment to maintain sweet potato agricultural performance and soil fertility, with potential to support long-term sweet potato cultivation. The negative effect of inorganic fertilizer on total soil nutrient concentration after two seasons needs consideration to avoid soil fertility mismanagement.
Conz, R.F., Six, J., Andrade, M.I. et al. Soil fertility maintenance with organic amendments to orange fleshed sweetpotato. Nutr Cycl Agroecosyst 119, 213–229 (2021). https://doi.org/10.1007/s10705-020-10111-8
Nutrient Cycling in Agroecosystems