Table Of Contents
Soil degradation is a major challenge to food security in sub-Saharan Africa (SSA), yet synthetic fertiliser use is hampered by high cost and limited access.
Nonetheless, rejuvenating the highly degraded soils requires organic fertilisers to replenish organic matter and micronutrients and ameliorate soil acidity. Yet, the uptake of organic fertilisers is limited by poor quality, long production time and scarcity of organic matter on the farm.
The use of saprophytic insects to recycle organic waste into affordable and high-quality insect-composted organic fertiliser products (ICOF) has attracted rapid attention globally. Our research aimed to determine the quality of ICOF generated from various waste streams and assess ICOF impacts on soil fertility, crop yield and nutritional quality, and suppression of soil-borne pests and pathogens. Data were collected using laboratory, greenhouse and field experiments involving ICOF, commercial fertilisers, and various test crops in Kenya.
Our findings revealed that insects require only 5 weeks to recycle organic waste into nutrient rich, mature and stable organic fertiliser, compared to 12 – 24 weeks required for conventional composting methods. We found that ICOF contains 3 – 9 folds higher macronutrients, and adequate secondary nutrients and micronutrients required for adequate crop growth compared to conventional organic fertilisers. Agronomic studies revealed that soil amendment with ICOF significantly increased the yields of crops such as maize (6 – 27%), kales (20 – 27%), tomatoes (22 –135%), French beans (38 – 50%), spinach (13 – 56%), bell pepper (8 – 151%), and Amaranthus dubius (10 – 11%) compared to commercial fertilisers. Use of ICOF increased crude protein (6 – 190%) and mineral contents of food crops, net income (10 – 154%) and return on investment (5 – 156%) better than commercial fertilisers.
Furthermore, we found that ICOF application increased soil water storage, nutrient release and synchrony for plant uptake, microbial populations, and reduced soil acidity compared to conventional organic fertilisers. Soil amendment with ICOF suppressed potato cyst and root knot nematodes, cabbage and onion root fly pests, and tomato bacterial wilt by up to 100%, 65%, and 35%, respectively. Our results highlight the positive role of ICOF in improving soil fertility and crop yield and nutritional quality by addressing the challenges of soil acidity, nutrient deficiency, soil-borne pets and diseases which is characteristic of most tropical soils.
These findings indicate that adoption of high-quality, affordable and multipurpose fertilisers such as ICOF will immensely contribute towards sustainable soil health management and transformation of food production systems for improved food security.
This work has received funding from the EU Horizon Europe research and innovation Program NESTLER project under Grant Agreement No. 101060762.
