Large quantities of crop residues are derived from farms each year and often destroyed by burning or burial when they could alternatively be recycled to produce energy and fertiliser. Most herbaceous crop residues are dry and thus most suited to combustion rather than anaerobic digestion. However high moisture vegetables and fruit residues are ideal for recycling via anaerobic digestion.
Animals produce excrement which can be recycled to produce energy and biofertiliser. In the New Zealand context where farm animals are not contained the excrement is distributed directly onto the soil. In this case the decomposition of the organic matter produces methane direct to atmosphere. Where farm animals are contained for feeding or milking then the excrement can be easily collected for recycling into energy and high grade fertiliser.
Soil management can be improved when agriculture residues are collected and recycled into high grade fertiliser which can be used when and where it will give the most beneficial value to soils.