Artificial fertiliser didn’t come around for any reason. Compost and Farm Yard Manure (FYM) is bulky for the amount of actual N, P, K and other elements it contains. Furthermore, the concentrations of elements are variable and the sources may be limited. As resources become more limited and as people realize the value of compost that goes beyond the elements added, there will hopefully be more recycling of these “waste” materials and an improvement in the sustainability of our wider society (including the use of composted sewage on e.g. green manure areas or tree crops).
On a practical level, there are some basic considerations. The approximate amount of nutrients added in the compost or FYM should be taken into account in the nutrient budget for a crop. If material is coming from outside the farm the organic certification may require hot composting, residue test and documentation etc.
In many cases, the hot composting or fermentation of FYM will be beneficial to control the loss of nitrogen and prevent too much nitrogen and disease-causing bacteria compromising crop quality or safety.
Attention should be paid to storage of materials before use or composting. Covering can reduce leaching problems and can keep some material dry and un decomposed before going into a hot compost.
Table: Nutrient Composition of Organic Materials (N,P,K)
The benefits of applying compost and farmyard manure include:
· Provision of elements required by crop
· Improvement in soil organic matter levels
and potentially: Material N % P % K % Dry Matter % Livestock Manure Cow manure 0.5-0.8 0.15-0.2 0.6-0.8 25-30 Horse manure 0.6-0.8 0.1-0.2 0.3-0.5 50-60 Pig manure 0.6-1.0 0.2-0.4 0.4-0.7 25-30 Poultry Manure (broiler) 2.0-2.5 1.5-2.2 1.0-1.5 60-75 Poultry manure (cage) 1.5-2.0 1.4-1.8 1.0-1.3 40-50 Sheep manure 1.5-2.0 0.4-0.7 2.0-2.5 50-60 Other Material Seaweed (kelp) 0.2 0.05 0.5 70-80 Fish meal 5.0-10 1.0 <0.1 80-90 Garden compost 2.0-4.0 1.0-3.0 0.5-1.5 65-80 Grain straw 0.3-0.7 0.1-0.15 0.8-1.3 70-80 Mushroom compost 0.3-0.7 0.1-0.3 0.7-1.2 70-85 Sewage sludge 3.0-8.0 1.0-3.0 0.3-0.8 60-80 Wood ashes – 1 5 95
· Provision of beneficial microorganisms to the soil
· Provision of active substances (acting as a biofertiliser)