Biosolids are a valuable source of crop available nutrients and organic matter that can help to maintain and improve soil fertility and biological activity. To fully realise the value of biosolids nutrients and to minimise the environmental impact of applications, clear and reliable technical information based on robust scientific evidence is required. An organic manures section was first included in the 7th edition of Defra’s “Fertiliser Recommendations Booklet (RB 209)”, published in December 2000. This provided comprehensive guidance on nutrient utilisation, including data on the typical nutrient contents of a range of biosolids products and other organic materials. Crop nitrogen (N) availabilities to the next crop grown were presented for each organic material in relation to soil type, application timing etc. An integrated nutrient management strategy was promoted, where organic material nutrients were balanced with manufactured fertiliser applications. The revised 8th edition of RB 209 (“The Fertiliser Manual”) has been enhanced to provide updated guidance on typical nutrient contents and N availabilities to the next crop grown of a wider range of biosolids and other organic material types. The guidance, produced using the latest evidence from field-based research and the recently updated MANNER-NPK software, provides a robust tool-kit for making best use of the nutrients supplied by biosolids and organic materials.
Keywords: Biosolids, organic materials, nutrient management, nitrogen, phosphate, potash, guidance
Treated sludges (commonly called biosolids) and other organic materials (e.g. livestock manures, composts, industrial ‘wastes’) are valuable sources of major plant nutrients and organic matter, which can be used by farmers and growers to meet crop nutrient requirements and to maintain soil fertility. Solid biosolids (e.g. digested cake, lime stabilised cake) and green compost (i.e. composted plant and vegetable material) are the most common non-farm organic materials that are applied to agricultural land, although increasing amounts of green/food compost will be produced in the next few years. The recycling of industrial ‘wastes’ to agricultural land is controlled by the Environmental Permitting Regulations (SI 2010). These Regulations allow the spreading of some industrial ‘wastes’ to agricultural land under an exemption, provided that certain conditions are met i.e. that they can be shown to provide ‘agricultural benefit’ or ‘ecological improvement’. The application of such ‘wastes’ must be registered with the Environment Agency.
In order for farmers and growers to fully realise the nutrient value of biosolids and other organic materials, and to minimise the impact of applications on the environment, it is necessary to have clear and reliable technical information. It is important that this advice should be based on robust scientific evidence, especially in light of the increasing cost of manufactured fertilisers and the requirements of legislation that are driving farmers to make much better use of nutrients.
An organic manures section was first included in the 7th edition of Defra’s “Fertiliser Recommendations Booklet (RB 209)”, which was published in December 2000 (Anon 2000). This provided comprehensive guidance on the utilisation of nutrients, including data on typical dry matter and nutrient (total nitrogen, total phosphate, potash, sulphur and magnesium) contents of a range of biosolids products and other organic material types. Crop nitrogen (N) availabilities (i.e. the percentage of total N applied available to the next crop grown) were presented for each organic material in relation to soil type, application timing etc. An integrated nutrient management strategy was promoted where biosolids and organic material nutrients were balanced with manufactured fertiliser applications, in relation to soil analysis and crop requirements.
This paper presents an overview of the biosolids and other organic materials data included in the organic manures section of the 8th edition of RB 209 (“The Fertiliser Manual”) (Figure 1; Defra 2010), which provides updated guidance on the typical nutrient contents of an enhanced range of biosolids, livestock manure, compost and other organic material types (i.e. paper crumble, mushroom compost, water treatment cake and food industry ‘wastes’). Organic material readily available N contents were provided for the first time and N availabilities to the next crop grown were revised, using the latest evidence from field-based research and the recently updated MANNER-NPK software (Nicholson et al. 2010).