Growth and Yield Attributes of Cowpea-Rice Under Intercropping System and Dual Compost-Mycorrhizae Fertilisation

Abstract

To boost rice production in the Adamawa region of Cameroon using environmentally friendly methods, the responses of rice plants to biological (mycorrhizae) and organic (compost) fertilisers, applied singly or in combination and cowpea in an intercropping system were investigated during the 2023 and 2024 cropping seasons. The experimental design was a completely randomised block with nine treatments, each of which was triplicated: rice-compost (C), rice-compost + mycorrhizae (CM), rice-cowpea + compost (N+C), rice-cowpea (N), cowpea in monoculture (NP), rice-mycorrhizae (M), rice-cowpea + mycorrhizae (NM), rice-no fertiliser (T−), and rice-NPK (T+). plots. When treatments were applied in solely-cowpea of the Bafia variety, results revealed that amending soil with compost benefited plants in height during both cropping seasons, with an average of 62.11 cm compared to 47.95 cm for solely-cowpea system. The number of nodule/plant, as well as the number of pods per plant were significant different (p < 0.05) between sole-cropped cowpea without input and cowpea grown with compost, compared to other treatments. Compost, mycorrhizae, and cowpea (singly or in combination) significantly (p < 0.0001) influenced rice height, tillering, heading, and grain formation. The effects of compost and compost + mycorrhizae treatments were closer to that of the positive control (NPK). Mycorrhization was negatively affected by the application of mineral fertiliser NPK (20-10-10), which almost inhibited and lowered the natural rice mycorrhization frequency to less than 10%. Rice yields per hectare were higher in plots treated with mycorrhizae (2.15 to 0.32 t/ha), mycorrhizae + compost (2.08 to 0.44 t/ha), and cowpea + compost (2.14 to 0.49 t/ha), closely approaching that of the NPK treatment (2.18 to 0.55 t/ha) over the two cropping seasons respectively. As the outcome, applying compost to rice-cowpea in an intercropping system could be recommended as an ecological production strategy to rice producers if high yields of both crops are to be sustainably maintained.