The amount of livestock manure applied in the UK each year would fill all the lanes of the M1, plus the central reservation and hard shoulder from Leeds to London, to a depth of 10 metres. But how can growers get the most of this valuable resource?
Producers and growers need to be sure of the nutrient content of livestock manure to help them reduce the need for bagged fertiliser, according to ADAS soil scientist, John Williams.
He said: “It is absolutely crucial to understand the nutrient content of manures before you apply them.”
But sampling needs to be done carefully to get a true representation of what is in the manure. For example, lagoons should be stirred to homogenise the slurry before spreading with samples taken periodically during store emptying to make sure the analysis provides a good measure of the slurry nutrient content.
Not all manures are the same and manures with a lot of readily-available nitrogen (N) should be handled carefully.
Mr Williams said: “Digestate is like rocket fuel so handle it with care. The nutrient content of digestate reflects the feedstock used in the anaerobic digestion process.”
Food based digestate can contain around 7 kg of total N/m3 (approximately 6 kg/m3 readily available N) and 25m3/ha would supply 175kg N per hectare, so matching application rates to crop demand is vital.
Mr Williams said: “Testing the digestate is the best way of knowing the nutrient content which is essential to make best use of the nutrients.”
Source: John Williams, ADAS