Production of Slow-Release Fertilizer based on cotton stems biochar and NPK : a sustainable fertilization alternative

Most of Burkina Faso's soils are deficient in nutrients due to inherent proprieties and inapropriate agriculture practices. Mineral fertilizer is the maint practices to improve sustainable yields. However, their high costs combined with inefficient application techniques reduce their effectiveness and limit their use by small farmers. The current challenge is to propose sustainable alternatives to optimize mineral fertilization in order to improve agricultural production and the resilience of small farmers. This study aims to develop and evaluate the performance of a slow release fertilizer based on biochar and NPK.
We assessed nutrient adsorption capacity on biochar activated with three levels of NPK; T1=100 kg/ha, T2=125 kg/ha and T3=150 kg/ha. The total N, P, K Ca and Mg adsorbed by biochar were evaluated through chemical analyses. P, K, Mg and Ca release dynamics were monitored by a sequential leaching test in distilled water and Calcium Chlorure (0.001M) at 2, 4, 7 and 14 days.
The results showed that nutrient retention capacity of biochar varied proprotionaly with NPK doses used to boost it. Biochar adsorbed nearly 992% of the nitrogen supplied by the NPK. More than 50% adsorbed nutrients are released in the first week of the experiment. This study showed that biochar could be used as a nutrient carrier to create Slow Release Fertilizer (SRF) and improve mineral fertilizers efficiencies in tropical wheathering soil.