S21 - Session O2 - Mineral nutrition of banana in organic agriculture

Authors: Marc Dorel *, Steewy Lakhia, Raphaël Achard

In the French West Indies, banana farming systems have undergone major changes over the last decade, ranging from the adoption of agroecological practices to conversion into organic farming. These changes have resulted in the use of organic fertilisers and live mulch soil cover. These practices reduce the risks of nitrogen leaching due to a better soil exploration by the root systems and a slow release of mineral nitrogen by organic matter. However, control of nutrient availability to the crop is more challenging under these practices. This is partly due to the competition for nutrients between the banana crop and the live mulch, and partly due to the variation in mineralization of the organic inputs with environmental and edaphic conditions. The objective of this study was to assess the effect of soil cover and type of fertilizer on banana nutrition, growth and yield parameters. The experimental design was a full factorial combination of three types of soil cover (Ploughed bare soil, weed live mulch, Puearia phaseolides cover) and two fertilization modes (chemical fertilization, organic fertilization) providing the same amount of nitrogen, phosphorus and potassium (300, 60, 500 kg/ha/year, respectively). Nitrogen and magnesium nutrition were better with chemical fertilization. With organic fertilization first cycle duration was longer but banana tree pseudostem diameter was higher. We observed larger bunches with P. phaseolides cover than with the other types of soil cover regardless of fertilizer type. The differences between the treatments reduced from the second cycle. In organic fertilizer treatments, the first cycle suffered nitrogen deficiency due to delayed release of nitrogen by organic fertilizers and due to the competition with the live mulch ground cover. The management of soil cover and fertilization is easier in established banana plantation where banana canopy shading decreases the competition with the live mulch cover.