Growth and yield response of cabbage (brassica oleracea var. capitata ‘star 3011’) to different liquid organic manure types and their combinations

The application of organic liquid manures is deemed a viable alternative to the application of inorganic fertilisers in vegetable production. This study was carried out to evaluate the effect of different types of liquid manure and their combinations on the growth and yield of cabbage, cultivar Star 3301. The study was conducted during the 2020–2021 and 2021–2022 seasons at the Tshaka Maoko Organic Nutrition Garden in Chiredzi, Zimbabwe. The experiment was arranged in a randomised complete block design with nine liquid manure treatments, namely, cattle, poultry, green groundnut, combinations of cattle-poultry, cattle-green groundnut, poultry-green groundnut, cattle-poultry-green groundnut, a negative control and a positive control. Liquid manure types and their combinations significantly affected cabbage growth and yield attributes, including days to heading, days to horticultural maturity, head diameter and head weight. The negative control showed the lowest values in all the attributes measured. The combination of cattle-poultry-green groundnut liquid manure showed the best performance and was comparable to the positive control and the poultry-green groundnut liquid manure. Crops treated with these treatments took a short time to form heads and to reach maturity and had heavy and large heads. The single liquid manure treatments showed intermediate performance. Among the single liquid manures, cattle liquid manure was the least effective. It was concluded that combining organic liquid manure, such as a combination of extracts from cattle, poultry and green groundnut, could be used as an alternative to inorganic fertilisers in cabbage production.