Teagasc has recently outlined the soil nutrient and financial values of a range of different organic manures.
While the nutrient values will vary depending on a number of factors, the figures are provided as guidelines for farmers and are based on average dry matter (DM) values.
The financial values of the organic manures are based on fertiliser prices from March 1, 2023.
The table below shows the available nutrient content and guide financial values for organic manures:
As the table above indicates, 1,000 gallons of cattle slurry (6% DM) spread using a Low Emission Slurry Spreading (LESS) system is estimated to have the same nitrogen (N), phosphorus (P) and potassium (K) value as a 50kg bag of 9-5-32 (N-P-K).
Meanwhile, 1,000 gallons of pig slurry spread using LESS is estimated to have the same N-P-K value as a 50kg bag of 19-7-20.
Based on fertiliser prices from March 1, 1,000 gallons of pig slurry is worth €54 in nutrient value and 1,000 gallons of cattle slurry is worth €47.
Looking at the nutrient value of poultry litter, the Teagasc table shows that broiler and turkey litters have the highest nutrient values. These values are expressed in kg/m3.
These results were discussed by Teagasc’s pig development officer Gerard McCutcheon at a recent farm walk.
Speaking to Agriland after the event, McCutcheon said: “What we’re trying to highlight is from an N point of view, going out on a growing cereal crop with organic manures, you’re getting to a point where you can replace a lot of your chemical N with organic N.
“Historically, with winter cereals, people went out and spread slurry in the autumn at 3,000 gallons/ac on winter cereal ground.
“A lot of that N was lost because you didn’t have a growing plant to take it up. When you go out on a growing crop, you can replace chemical N with slurry. The P and K was getting full use always but it’s also possible to get the full N response.”
The Teagasc officer continued: “By using organic fertilisers you’re building up your soil organic matter and carbon and by doing so you’re helping to improve the structure of your soil.
“Where you have continuous tillage and are going out with chemical fertiliser, it’s an issue tillage farmers need to be aware of in the sense the soil isn’t as resilient as it could be.”
McCutcheon is encouraging tillage farmers to use more pig slurry on actively growing crops to get more of the N value from it.