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Fertiliser Choice And Soil Chemical Health
As part of the European Green Deal we must reduce our chemical Nitrogen application by 20%. Reduced nitrogen application and reduced profits at farm level go hand in hand, unless we can grow the same amount of grass with this reduced nitrogen application. We can do this by:
– making better use of the slurry,
– sowing clover,
– improving Nitrogen use efficiency with better soil pH, P and K indexes,
– increase soil nitrogen mineralisation through improved soil biological health.
Soil Chemical Health has declined on Irish Farms
Between 2015 to 2019 some gains were made in terms of soil chemical health, however between 2020 and 2021 dairy and drystock farms are showing a combined 5% drop in soil chemical health. Results in 2021 now show that 47% of dairy farms had soil pH below the optimum of pH 6.3.
Chemical Phosphorus and Potassium fertiliser application:
This decline in soil chemical health is disappointing and has the potential to impact our productivity and profitability. But this decline is all the more important when we consider where our fertiliser usage patterns are headed and the impact this may have on 2022 and 2023 soil chemical health figures. In 2023 we use 61% of the chemical P fertiliser that was used in 2021 and in 2022 we used 75% of the chemical P fertiliser at
we used in 2021. The same trends apply to potassium application, with 2023 sales at 65% of 2021 sales. While this maybe be understandable with the historic high fertiliser prices one wonders how this will affect soil chemical health.
Soils that are Index 3 for phosphorus grow 2TDM/ha more grass than soils that are index 1 for phosphorus.
What fertiliser products to use?
We are being limited on the nitrogen we can spread but the amounts of P and K we are allowed to and advice to use are based on our soils P and K status. With the soil P and K status on decline we should be using more chemical P and K fertilisers. Not the opposite. The fertiliser you can buy can be Nitrogen only, Nitrogen and Phosphorus combined, Nitrogen and Potassium combined, but also Phosphorus and Potassium combined and Phosphorus only and Potassium only.
While we drop our chemical Nitrogen application, we need to make better use of the range of fertiliser products that are available to meet our soils nutrient needs. Our usage of 0-7-30 for example has not increased. We must take appropriate action to meet our soils P and K requirements as we limited our nitrogen application.
4 point plan to improve soil chemical health:
– Take a soil sample every 5 ha
– Apply lime where needed to improve soil pH
– Use slurry on low P and K index soils
– Contact your Area Sales Manager to design an appropriate fertiliser plan for your farm.