Waste-derived fertilizers can increase phosphorus uptake by sugarcane and availability in a tropical soil

Background: The use of highly water-soluble phosphorus (P) fertilizers can lead to P fixation in the soil, reducing fertilization efficiency. Waste-derived, low water-solubility sources can potentially increase sugarcane's P uptake compared to triple superphosphate by reducing adsorption to the soil. Aims: We aimed to test struvite, hazenite, and AshDec (R) for their agronomic potential as recycled fertilizers for sugarcane production in a typical tropical soil. We hypothesize that these sources can reduce P fixation in the soil, increasing its availability and sugarcane's absorption. Methods: In a greenhouse pot experiment, two consecutive sugarcane cycles, 90 days each, were conducted in a Ferralsol. The recovered sources struvite, hazenite, Ash Dec (R), and the conventional triple superphosphate were mixed in the soil in three P doses (30, 60, and 90 mg kg(-1)), aside a control (nil-P). At both harvests, sugarcane number of sprouts, plant height, stem diameter, dry mass yield, shoot phosphorus, and soil P fractionation were investigated. Results: At 90 days, struvite and hazenite performed better for dry mass yield (70.7 and 68.3 g pot(-1), respectively) than AshDec (R) and triple superphosphate (59.8 and 57.4 g pot(-1), respectively) and for shoot P, with 98.1, 91.6, 75.6, and 66.3 mg pot(-1), respectively. At 180 days, struvite outperformed all treatments for dry mass yield (95.3 g pot(-1)) and AshDec (R) (75.5 mg pot(-1)) for shoot P. Struvite was 38% and hazenite 21% more efficient than triple superphosphate in P uptake, while AshDec (R) was 6% less efficient. Soil had higher labile P under struvite, hazenite, and AshDec (R) than triple superphosphate by the end of the first cycle, while only the later increased nonlabile P by the end of the experiment (180 days). Conclusions: Waste-derived P sources were more efficient in supplying P for sugarcane and delivering labile Pin 180 days than triple superphosphate.