Slow-release hydroxyapatite fertilizer from crab shells waste for sustainable crop production

Slow-release fertilizer (SRF) is an alternative to more efficient fertilization. SRF can gradually release nutrients in fertilizer, hence the nutrients needed by for the plant growth will be available for a more extended period. In this study, SRF was made by mixing single fertilizer (urea and ammonium sulfate) with hydroxyapatite particles from crab shell biowaste. Slow-release hydroxyapatite fertilizer synthesized with a ratio between single fertilizer and hydroxyapatite powder of 6:1, then applied to grow Capsicum annuum pepper plants. The result showed that applying hybrid fertilizer affected the growth and yield of Capsicum annuum pepper plant, by enhancement of plant height up to 150 %, stem diameter up to 168 %, number of leaves up to 167 %, number of fruits up to 449 %, fruit diameter up to 200 % and fruit weight up to 234 %, compared with unfertilized plant. The SRF fertilization slightly affect the soil acidity, however the pH changed showed no effect to the plant growth. The use of HA as fertilizer promotes more sustainable crop production, by efficient nutrient uptake and utilization calciumrich biowaste.