Nutrients enriched biochar production through Co-Pyrolysis of poultry litter with banana peduncle and phosphogypsum waste

Poultry litter (PL) utilisation has been widely studied for production of phosphorus (P) rich biochars. Recent research documented co-pyrolysis of PL with nutrient rich chemical additives like rock phosphate, phosphoric acid and magnesium (Mg) salts for production of P-Mg enriched biochar with improved P use efficiency. However, research is highly scarce on utilisation of waste materials for production of PL biochar enriched in P, potassium (K) and sulphur (S). In this context, present work investigated co-pyrolysis (700°C, 10°C/min, 1h residence time) of PL with banana peduncle (BP) and phosphogypsum (PG) in different w/w ratios (1:1:1, 1:2:1, 1:3:1) of BP-PL-PG for production of K-P-S enriched biochars composites. These biochars mainly showed variations in their K-P-S contents. The K (5.1%) and S (11.35%) enrichment was relatively higher in BP-PL-PG (1:1:1) biochar than PL biochar (K-3.70% and S-0.96%). However, P content was higher in PL biochar (4.48%) and was reduced in biochar composites. The P contents were 3.84, 2.84, and 2.44% in BP-PL-PG (1:3:1), BP-PL-PG (1:2:1) and BP-PL-PG (1:1:1) composites respectively. In biochars, P was present predominantly as Ca-Mg bound form. Furthermore, best fit of second order kinetic model indicated slow-release behaviour of P from biochars and composites. These results highlight the scope of co-pyrolysis of PL with selected wastes for production of multi-nutrients enriched biochars with improved nutrient availability for soil application.