The benefits and limitations of nutrient sources:
Environmental: Bulky organic; Good recycling of organic material; Runoff from heaps can pollute waterways; Fertilises; Issue of energy used in manufacture; Some quick acting materials can leach and pollute waterways (algae bloom); Salt residues can build up in soils or compost to toxic levels.
Health and Safety: All weight of handling; Bulky organic pathogen content? (hygiene); Allergy to contents possible Attracts dogs cats & foxes to the plants Bone meal unsterilized may carry CJD – all commercial types now sterilised Imported organic anthrax in unsterilized blood and bone meal
Timing of application: Bulky organic winter digging in; Spring – use as mulches; Fertilisers: Base – use in preparation stage; Top/liquid/foliar – apply to growing crop as required; Lawns – spring and summer, high nitrogen up to August; Spring cabbage – late March to give a boost to growth after the winter leaching of nutrients from the soil.
Variability of the material: Bulky organics nutrient content very variable; Organic fertilisers slightly variable; Inorganic fertiliser stable content.