Fertilisers produced from agricultural by-products are referred to as bio-based fertilisers. Globally, rock phosphate and potash reserves are being depleted. Nitrogen is heavily dependent on natural gas for its production via the Haber-Bosch process. Europe completely relies on importing P and K. With such a strain on these finite resources, there is market potential for mineral fertiliser alternatives. Bio-based fertilisers are a by-product from the farming industry, domestic sources and commercial industries such as dairy processing. Sources of bio-based fertilisers include animal manure, sewage sludge, food-industry waste, rural/urban green waste and forestry by-products. The types of bio-based fertilisers produced include compost, digestate, struvite, grass juice and ammonia nitrate/sulphate. These products have many benefits, including reduced transport costs, replacing synthetic fertilisers in areas characterised by nutrient deficiencies, additional income for farmers and retaining nutrients on the farm. The use of these bio-based fertilisers helps to close the nutrient cycle loop by recycling organic products and keeping these important resources in the bioeconomy.
