All-round soil health is key to reducing farm emissions
Soil fertility management is helping to deliver emission reduction targets, a primary goal of the Teagasc Signpost farms programme, Mark Plunkett, Teagasc Soil Specialist, tells us more.
Good overall soil fertility delivers increased supply and efficiency of major nutrients such as nitrogen (N) and phosphorus (P). Increasing the supply of soil-released N and increasing the efficiency of applied N (Slurry / Fertiliser) is a key step to reducing our reliance on bag fertiliser N.
Balanced soil fertility of primary (N, P & K) and secondary (Ca, S & Mg) nutrients is the foundation to improving farm N use efficiency and reducing farm N surpluses annually. Building soil fertility to the optimum (where soil is at pH 6.3, P & K Indices are at 3) increases N use efficiency by 100% plus it helps reduce soil nitrous oxide (N2 O) emissions. Nitrous oxide being one of the most powerful greenhouse gases.
Over the four years of the Signpost programme the following farm practices have delivered improvements in overall soil fertility and reduced N use on dairy, beef and tillage farms:
- Monitoring soil fertility changes through regular soil analysis
- Regularly updating farm fertiliser plans with new soil sample information
- Consulting the fertiliser plan on a regular basis for management of all major nutrients (lime, slurry & fertilisers)
- Implementing a liming plan and targeting improvements in grassland soil pH 6.3 to 6.5
- Applying additional lime, where clover establishment is planned, to pH 6.5 to 6.8
- Selecting high P and K compounds such as 18-6-12+S to deliver a balanced supply of N, P, K & S on grazing areas of the farm
- Targeting cattle to silage fields to de- liver the majority of the grass crop’s P and K and balancing this with a suitable fertiliser compound
- The use of slurry analysis to adjust for slurry N supply & fine tuning fertiliser advice to ensure a balanced nutrient supply
- Purchasing fertilisers with suitable levels of sulphur (S) for grazing & silage fields
- Omitting P and K applications on Index 4 soils and making use of soil fertility reserves
Nutrient management
To date in the Signpost farms programme better nutrient management planning has resulted in improvements in soil fertility. In addition it has contributed to a reduction in fertiliser N rates on dairy farms from 201kgN/ha to 160kgN/ha and on beef farms from 116 to 87kgN/ha. Increasing N use efficiency delivers many win-wins on farm. Not least of these are cost savings from reduced farm fertiliser N use through reducing N surpluses and farm carbon emissions.