Farm Ireland
Independent.ie

Wednesday 18 October 2017

Get the balances right with your fertiliser usage

Step 5 – Make sure the fertilisers used are properly balanced

A balanced plant nutrient supply is very important during the growing season. It is especially important for productive ryegrass swards that soil reserves can supply sufficient nutrients to meet the peak demands at particular stages during the growing season.

Soil analysis plays a key role here as it gives a measure of the soil's ability to supply both major and minor nutrients. Fertiliser applications can then be tailored to supply the correct nutrient balance.

The type of fertiliser selected will depend on the soil nutrient status, the crop demands and the rate of organic manure application.

For example, the nutrient requirements for a grazed sward will be quite different to that of a grass silage sward.

A grazed sward will often require a fertiliser to deliver a P:K ratio of between a 1:2 to 1:4 and fertilisers such as 18-6-12 or 24-2.5-10 supply P:K within this range.

However, a silage sward will require a P:K ratio of 1:6 and fertilisers such as 15-3-20 or 10-5-25 supply P:K within this range.

Fertilisers with appropriate N-P-K ratios need to be used for these different grass crops to ensure the correct delivery of N, P and K to meet early and seasonal crop nutrient requirements to maximise grass growth.

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Soil fertility needs to be managed on a long-term basis with the aim to maintain soils at P and K index 3 for optimum production.

It is very worthwhile comparing old soil test results to current soil test results. This will provide a sound basis for tailoring a fertiliser spreading plan for the soils on your farm.

It will also help identify fields that need extra nutrients, for which slurry and farmyard manure is a cost-effective way of building these soil fertility levels.

Soil fertility changes very slowly over time so a small annual investment in lime, P and K now will pay long-term dividends in the future.

Irish Independent