Effects of acid treatment and composting on bones used as fertilizer
The aim of the work was to analyse the compostable properties of bone powder produced via different treatment methods and industrial conditions, and to study their effect on plant growth and phosphorus uptake. The bones were treated in water with different temperatures, bone-water ratios and treatment times. Further treatment was carried out with citric, nitric and sulphuric acid with different concentrations, temperatures, bone-water ratios and treatment times. Industrial bone powder was composted under model industrial conditions.The available phosphorus content of these materials was estimated using ryegrass ( Lolium perenne ) as indicator plant in a climatic chamber.The water-soluble phosphorus content of the bones increased in the citric acid and sulphuric acid treatment, depending on the water treatment conditions and the acid concentration. This increase amounted to about 30 times (0.32–8.51 mg/100 mg) compared to the water treatment.The results of the plant test demonstrated that the phophorus content of treated bone powder and compost was readily available to plants. The phosphorus content of the compost was available over a longer period.