Grazed grass continues to be the most cost-effective form of animal feed available in Ireland and through maximising its yield and quality, profitability can be optimised.
Farmers should aim to have stock grazing for a minimum of 280 days per year; however, in order to achieve this, an appropriate fertiliser plan should be developed in conjunction with a grass budgeting system to ensure optimum grass utilisation.
Soil fertility
The latest Teagasc figures indicate that just 15% of Irish soils are in good status nutrient wise. The 15% referred to are Index 3 soils for phosphorous (P) and potassium (K) and meet the target pH of 6.3.
This means 85% of soils are deficient, indicating a low level of soil fertility, resulting in a loss in grass production and in the efficiency of applied nitrogen (N).
As the remaining zones are now open for organic and chemical fertiliser application, it is important to give due consideration to your fertiliser plan.
The main nutrients requiring attention are lime, N, P and K. In order to optimise your grass production, the levels of P, K and lime must be corrected. Both P and K soil levels are recommended to be at Index 3 as lower levels will give reduced grass growth of up to 30%, especially at the shoulders of the season.
Soil testing
Soil testing is highly recommended as it allows you to make executive decisions when planning your fertiliser applications.
By referring to your most recent soil analysis results you can develop a fertiliser programme for the year that ensures you apply the correct nutrients. Your advisor can assist in completing a soil analysis and ensuring that any deficiencies are identified.
Maximising grass yield
As sulphur (S) deficiencies are common on sandy, free-draining soils with low levels of organic matter, it is recommended that farmers use an NPKS compound to encourage root development and increase tillering.
S application, where required, will improve dry matter (DM) yields and grass quality. Furthermore, the use of S will increase N use efficiency, improving protein levels and grass palatability.
It is important to take care with K application as excessive volumes will cause magnesium (Mg) levels to diminish, leading to grass tetany. It is recommended to build your K levels at the back end of the year, through the use of products such as Muriate of Potash (MOP) in the autumn.
In order to improve K levels on Index 1 soils, it is recommended to apply 60-95kg/ha and supplement Mg requirements through fertiliser application with products such as Target Fertilisers’ Sweetgraze or Richgraze.
Alternatively, you can supplement Mg through feed licks, bolus or trace elements in water.
The use of slurry will assist with your grazing requirements, but it is best to reserve slurry for silage ground where the K requirement is higher.
Typically, 1,000 gallons of cattle slurry containing a nutrient value of 7% DM will be the equivalent of 5-5-30 in bag form. When using a trailing shoe, the N content will be 3% higher due to the reduction in N losses.
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