Organomineral phosphate fertilizer from sugarcane byproduct and its effects on soil phosphorus availability and sugarcane yield
The recycling of agricultural by-products to produce organomineral fertilizers and using them as soil amendments to improve soil physical and chemical characteristics is a feasible disposal solution for the sugarcane industry. This study aimed to evaluate the agronomic performance of a bio-based phosphate (P) fertilizer produced from mineral phosphates (Gafsa rock phosphate and TSP) and filter cake (FC) in two distinct soils varying in their particle sizes, namely clayey (CLY) and sandy loam (SDY). Biological tests were carried out to determine the performance of the OF for sugarcane production against commercial P sources. The addition of filter cake (+FC) was responsible for an increase in yield when compared to soils that did not receive it (−FC), yet similar sugarcane production for either soil was obtained. Phosphorus use efficiency (PUE) was ~10% higher in CLY under TSP +FC compared to phosphate rock (RPR) −FC. On the basis of our P fractionation data, the addition of FC decreased P concentrations in the more labile P fractions. Phosphorus X-rays Absorption Near Edge Structure (XANES) analysis indicated that even though P was predominantly associated with Fe- and Al-(hydr)oxides, application of FC led to a change in P speciation, causing a shift from Fe-bound P in the soil that did not receive filter cake into Al-bound P, and to an increase in P associated to organic compounds in the soil receiving this amendment. Our findings showed that PUE and dry matter yield of sugarcane can be increased in weathered soils when organic and inorganic P sources are combined to supply this element.