Characterization of bone and dung biochars for potential use as precursors for artificial fertilizers

Abstract

The Fourier Transform Infrared technique was utilized to measure the infrared spectra of bone and dung chars at ambient temperature. The spectra of the investigated char samples showed some notable similarities, suggesting that the compounds have functional groups which display bands at similar wavenumbers in IR spectrum. Additionally, correlations between the chars and the terra preta soils were found. This implies that the investigated biochars and the terra preta soils share comparable characteristics. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy showed the existence of calcium, phosphorus, magnesium and oxygen in the bone char which are classified as macronutrients. In addition, the bone char contained two micronutrients (nickel and chlorine) and one non-essential nutrient (sodium). The dung char was constituted with all the macronutrients found in the bone char and in addition it had traces of sulfur which is also a macronutrient. Iron, manganese and chlorine were present in the dung char as micronutrients. There was also the presence of sodium and aluminum which are classified as non-essential nutrients. Zinc which is also fundamental in soil fertility was detected using Atomic Adsorption Spectroscopy in all the chars. Both the samples are alkaline with pHs ranging between 9 and 11. The results of this research will be useful in determining which biochars are best suited for production of synthetic fertilizers.