Mineral fertiliser equivalence value of dairy processing waste and derived strubias products
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Date
2023-03-09Embargo Date
2025-03-09
Author
Shi, Wenxuan
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Abstract
Globally, agriculture urgently needs alternative sources of phosphorus (P). Presently, global
agriculture is over-reliant on inorganic mineral P fertilisers sourced from finite mining sources.
This is especially relevant in the European Union (EU), since Europe lacks natural rock
phosphate deposits. There are many alternative organic sources of P, which could be used at
low cost in agriculture to grow crops. For example, as one of the largest agricultural-food
sectors in EU, the dairy processing industry generates large amounts of P-rich dairy processing
sludge (DPS), which can be further processed into secondary-raw-material-based fertilising
products, referred to as STRUBIAS (STRUvite, BIochar, or incineration AShes). As DPS and
DPS-derived STRUBIAS products have the potential to be used as bio-based fertilisers, to
encourage farmers to choose such fertiliser alternatives and stimulate their access to the market,
the EU has implemented changes to the Fertiliser Regulations. To date, few studies have
focused on the potential of these products to be used as agricultural fertilisers, which has
hindered their incorporation in agricultural nutrient management planning. This thesis aims to
address the knowledge gaps associated with their agronomic performance and potential
environmental risks when reused as fertilisers in agriculture. Specifically, the aims of this thesis
were to: (1) quantify the nutrient and metal content of a range of DPS and DPS-derived
products (2) compile a database and develop a MS ExcelTM calculator programme to provide
farmers with a quick and safe way to reuse these products (3) determine the mineral fertiliser
equivalent value (MFE) of a range of these products when used to grow ryegrass and spring
wheat, and (4) examine how the different application rate (optimal versus high) and calculation
methods (with and without chemical fertiliser response curves) affect MFE results, which, in
turn, will enable a standard approach to be used in fertilisation.