The production of banana in Sub-Saharan Africa suffers widely from low nutrient availabilities in soils. To counter this limitation, fertilizers must be applied that provide a balanced supply of nutrients. Specially designed fertilizer blends can be used that contain nutrients like nitrogen, phosphorus, potassium, sulfur, and others in proportions that are aligned with soil fertility status and crop requirements. Readily accessible single nutrient fertilizers and existing infrastructure in Sub-Saharan Africa can be used to mix these specialized blends for farmers. Note that banana and plantain have a particularly high requirement for potassium, and that blends for root crops are also suitable for this crop as well. Applying the right fertilizer at the right time and place to banana and plantain greatly enhances productivity and nutritional value and strengthens resilience to drought and pests. Specialty fertilizer blends allows farmers to obtain greater returns on input investments.
Formulations of blended or compounded fertilizers balance and replenish nutrient stocks in soils, which ensures that the added inputs are utilized more efficiently for increasing banana and plantain production. Blending technology offers a very large degree of flexibility to adapt fertilizer formulations in line with general soil characteristics and production objectives, as is prescribed by the guiding principles of integrated soil fertility management. The various elements that are mixed have specific benefits. For example nitrogen, phosphate and potassium promote stem growth, flowering and bunch filling, sulfate reinforces photosynthesis and transpiration, and calcium, magnesium and zinc enhance the uptake of nutrients and water from soils. Use of specialty fertilizers for banana and plantain has very strong synergies with improved varieties as larger bunches necessitate greater nutrient demand. Applying micronutrients results in fruit with greater nutritional and energetic value that help overcome deficiencies in rural communities. The right nutrient balance promotes uniform ripening and prevents splitting of immature and early ripened fruit.
Fertilizer blending technology is suitable for all major growing areas and especially important in low fertility soils. Split applications of specially blended fertilizers greatly improve the health of plantations and their yields and nutritive value. This approach is particularly important when farming highly weathered soils characterized by low fertility and pH imbalance. Note that fertilizer mixes designed for banana can be suitable on root, tuber and flower crops; and this versatility is advantageous for input manufacturers, distributers and farmers alike.
Specific nutrient formulas result from blending a wide range of solid granular fertilizers like urea (46% N), potassium chloride (52% K), single superphosphate (16 to 20% P2O5, 11 to 21% Ca and 11 to 12% S) or triple superphosphate (46% P2O5). Micro-nutrients like zinc, boron, amongst others can be added in solid form or impregnated as liquid. An example of a mixed top-dressing fertilizer is “Banana blend” from Zambian with 12% N, 3% P2O5, 22% K2O, and 35% organic matter which should be applied at 100 g per plant every month. Examples of specialty compound fertilizers for banana and plantain are Java®, Power®, Nitrabor® and Winner® from Yara which contain N, P, K, S, Zn, Ca, Mg, Fe, and B that serve different stages of the production cycle. Another useful blend for topdressing root, tuber and fruit crops (5:13:21 + MgO 5.8% + CaO 4% + S 3% + Zn 0.4%) manufactured by MEA Fertilizers in Kenya. These fertilizers are typically sold in bag sizes ranging from 5 to 50 kg.
Information about the nutrient deficiency and imbalance in specific growing areas is contained within soil maps and past agronomic trials and is often sufficient for developing blending formulations. The production of the specialty fertilizer blends is also subject to the availability of different single fertilizers. Manufacturing of blends is done using a dry rotary system available at medium to large scales and is best packaged into sizes needed by farmers. Banana and plantain require NPK at rates of 200-40-200 kg ha-1 spread across the production cycle. When planting, a spot application around the base of plants at 3 to 6 month intervals is advised. Some of these inputs may be substituted with organic inputs, particularly for ratoon crops.