Effects of Tithonia diversifolia biomass soil amendments on three annual crops (peanut, maize and soybean) grown in succession in an intercropping system with bananas in Ultisol

A field experiment was conducted to assess the effects of using biomass of T. diversifolia as a green manure soil amendment on three annual crops (peanut, maize and soybean) cultivated in a banana intercropping system in Ultisol. The experiment was arranged in a split plot design with two nutrient sources (chemical fertiliser (CON) and T. diversifolia biomass (Ti)) for the banana plants in the main plots, and three application rates of biomass of T. diversifolia for the three annual crops (peanut, maize and soybean) in the subplots. In the banana intercropping system, the application of chemical fertiliser to supply 250 g N plant−1 for the banana resulted in increased growth of the peanut plants, compared with the application of T. diversifolia (at the same input of N), though the yield of the peanuts was similar in both treatments. In the maize and the soybeans, the yields were significantly higher in the CON treatment compared with the Ti treatment. Increased application rates of T. diversifolia biomass for the annual crops (13.8 t ha−1 T. diversifolia (dm) for maize and 3 t ha−1 T. diversifolia (dm) for soybean) resulted in increased yields in the maize and soybean. It was concluded that under the poor soil conditions of the Ultisol, the application T. diversifolia as a green manure promoted the production of the annual crops in the banana intercropping system, even when the green manure was the only source of nutrients.