Biomass yields and crude protein content of two African indigenous leafy vegetables in response to kraal manure application and leaf cutting management

Abstract

African indigenous leafy vegetables have the important role of providing essential minerals, vitamins and amino acids in diets of poor smallholder farmer households in sub-Saharan Africa. A study was conducted to quantify the influence of applying cattle and goat manure on the biomass yields and crude protein content of two commonly used African leafy vegetables (Cleome gynandra and Amaranthus hybridus) when subjected to varying leaf cutting management. Treatments for each vegetable consisted of a combination of three manures (control, cattle and goat) and three cutting regimes (cutting edible leaves, all harvestable leaves and cut only at the end) utilised in randomised block design. The results showed significant increase in leaf biomass yields and crude protein content of both vegetables due to manure application. Goat manure was superior to cattle manure due to its higher quality in terms of nutrient content and lower C:N ratio. Cutting the edible leaves more frequently, every fortnight, was associated with the highest leaf biomass yield and crude protein in treatments where manure was applied. It was concluded that potential exist for smallholder farmers to benefit from adopting appropriate manure and leaf cutting regime. A combination of goat manure and frequent cutting of the tender edible leaf tips is recommended. The results point to the potential of maximizing biomass yield and quality of the vegetable leaves by adopting appropriate nutrient supply and leaf cutting regime.