Another organic fertiliser is farm animal manure. It is mainly commercially available as packaged digested manure. Fresh manure has some important disadvantages. For this reason, the use of digested manure is mainly recommended.
What is manure
Manure is considered an N-rich and partly K-rich fertiliser. The nutrient content depends both on the species of animal and the ration on which it is fed. A protein-rich ration leads to a higher nitrogen content. In order to estimate nutrients, a sample analysis is required. However, a general picture is that poultry manure has a higher concentration of nutrients.
The use of manure as an organic fertiliser has some important advantages. First of all, huge quantities of manure are produced in farm animal husbandry units. As a consequence, the aquifers in these farms are often polluted with nitrates. The use of manure as fertiliser therefore helps to reduce this phenomenon. It is also a rich source of trace elements. Finally, it improves the physical properties of the soil, such as water retention and aeration.
One disadvantage is that crops have high N requirements. To meet these requirements, large quantities of manure are needed. However, in this way much higher amounts of phosphorus are applied than the crops need. Phosphorus is not toxic. However, large amounts in surface waters contribute to the eutrophication phenomenon. Finally, it is necessary to know where manure comes from
In conclusion, the use of manure as an organic fertiliser has some important advantages. However, care is needed in its use. There are risks which are increased when we do not know its origin and it is not certified. In conclusion, a quantity of manure can also be used in the compost heap. This improves the nutrient content of the heap.