Local farm research organisation, AgriSearch has created an online tool using Microsoft Excel which allows farmers to input their data and see where they might stand in relation to some of the key issues identified in the Nutrients Action Programme (NAP).Those key issues include the annual manure nitrogen (N) loading per ha, which for non-derogated farms is currently limited to 170kg. Under the latest NAP proposals, any farm with a manure N loading over 150kg will be classed as intensive, meaning it will have to abide by new phosphorus (P) limits.
Local farm research organisation, AgriSearch has created an online tool using Microsoft Excel which allows farmers to input their data and see where they might stand in relation to some of the key issues identified in the Nutrients Action Programme (NAP).
Those key issues include the annual manure nitrogen (N) loading per ha, which for non-derogated farms is currently limited to 170kg. Under the latest NAP proposals, any farm with a manure N loading over 150kg will be classed as intensive, meaning it will have to abide by new phosphorus (P) limits.
The second main output from the calculator relates to how much chemical N fertiliser can be spread given new proposed limits for grassland, while the final output is the P balance on the farm.
Scenarios
At a webinar on Monday launching the new AgriSearch tool, a number of scenarios were presented.
A 150-cow dairy farm on 90ha producing 8,750l from 3.5t of concentrate had a P balance of 12.7kg. To get below 8kg P/ha in 2029 the farm would either need to find an additional 52.9ha or cut livestock by 37%.
However, if the farm was “stressed” due to bad weather or bovine TB, this P balance could easily reach 20kg P/ha. To get below 8kg P/ha, an extra 134.5ha would be required.
Even more land is required if it is a very high-input herd producing over 10,000l from 5t of concentrate.
“Once you cross the 7,500 to 8,000l threshold, you really are struggling to get to the eight to 10 P category,” said Jason Rankin from AgriSearch.
Beef and sheep
Other examples included two 40 ha farms. The first is reasonably well stocked with 30 sucklers to beef and 100 breeding ewes.
Despite importing 80,000 gallons of slurry each year, it is still well within proposed limits, with a manure N load of 138.1kg/ha and a P balance at 5.8kg.
A dairy calf to beef farm, buying in 80 calves annually, is feeding significantly more concentrate (104t versus 35t), so the P balance is closer to the limit at 7.5kg.
The AgriSearch NAP calculator is available at www.agrisearch.org.
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