Agronomic Efficiency of Biochar-Based Organophosphate Fertilizers

The development of fertilizers with integrated protection has been proposed to increase the efficiency of phosphate fertilization. The aim of this work was to evaluate the efficiency of organophosphate fertilizers produced with biochars, made from coffee straw (CSB), poultry litter (PLB), and eucalyptus bark (EBB), in coating mode and homogeneous mixture, comparing them to triple superphosphate (TSP). The treatments were with three biochars that make up the fertilizers (CSB, PLB, and EBB), two methods of fertilizer preparation (homogeneous mixture and coating), and three proportions of biochar/TSP in the composition of the fertilizers (10, 20, and 30%). A dose of 30.5 kg ha–1 of P was applied to a Red-Yellow Latosol, and the cultivation of maize was defined as the test plant. Compared with TSP, biochar-based organophosphate fertilizers showed greater agronomic efficiency (10.8%), P recovery (2.4%), and greater P availability after harvest (11.6 mg kg–1). PLB-based fertilizers stood out among the highest agronomic efficiency means and P recovery, in addition to presenting a greater amount of P available in the soil after harvest (31.94%). The fertilizers produced in the coating mode promoted the greatest P availability in the soil (5.1%). However, regarding the agronomic efficiency and P recovery, only fertilizers produced from EBB differed from each other, with fertilizers produced in coating mode showing higher means (111.4 and 29.8%, respectively). Our findings suggest that the 30% biochar/TSP ratio was most effective in enhancing soil P availability and plant uptake, while also extending the residual effect of P in the soil.