Characterization of bonechar as a soil amendment in tropical soils

Tropical soils usually lack phosphorus (P) availability due to the high P retention associated with these soils, limiting plant productivity. Brazil is the largest tropical country and worldwide exporter of beef, where overgrazing and frequent slash and burn practices resulted in large areas of degraded pastures. Land degradation and lack of releasable P could potentially be solved using a byproduct of livestock activities– bones– with high P content. The present work evaluates an industrial bonechar (obtained by the pyrolysis of bones) for its potential as a soil amendment. The bonechar’s structure and chemical composition were evaluated by using x-ray diffraction, scanning electron microscopy and chemical analyses. The results showed that: i) bonechar is composed mainly of the mineral hydroxyapatite, known to bond with organic molecules of different sizes, which could increase the soil organic carbon stock, and ii) the plant available P in the bonechar is high, 2,800 mg kg -1 . Although more studies are needed on bonechar, mainly on its field application, the present work reinforces the production and agricultural use of it as a relevant soil amendment to recover degraded soils in tropical regions.