Five steps to summer fertiliser management

Stock image
Stock image

Gordon Peppard

Even where grass appears to be getting ahead on farms, it is essential to keep nitrogen spread after each grazing.

It is very difficult to maintain quality in grass without nitrogen.

Grass growth has really taken off in the last couple of weeks and it may seem like an ideal opportunity to cut out a round or two of nitrogen application.

It is still better to keep nitrogen spread after each grazing, even at lower stocking rates, where the level of nitrogen applied can be cut to 15 units per acre.

Higher stocking rates can apply up to 27 units after each grazing.

Every tonne of grass needs to get 24 units of nitrogen per acre from the soil. The soil on its own won't supply this.

Keeping nitrogen spread keeps good-quality leafy grass ahead of the stock, maximising weight gains, and if paddocks get too strong, don't be afraid to take them out as high-quality baled silage.

Many yards are depleted of silage reserves and every opportunity to rebuild stocks in the yard should be taken.

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Nitrogen can be applied as a compound fertiliser where P and K are also low.


Sulphur is often the forgotten nutrient in grassland:

it is essential for grass growth and is closely associated with nitrogen uptake and efficiency.

Sulphur deficiency can lead to a reduction in the quantity and quality of grass produced.

Deficiencies will occur where more is removed from the soil, as a result of crop growth and leaching, than is replaced by either fertilisers or depositions from the air, which come from smoke discharges from industrial and domestic fires.

There is no soil test for sulphur. Lighter soils tend to be more prone to being deficient in sulphur.

On grazing ground it is recommended to apply 15-20 units of sulphur per acre per year from April to July; therefore consider spreading a product like Sul CAN, which contains 5pc sulphur or a compound, with sulphur included instead of CAN.

Apply in two or three splits over the summer. Silage ground requires 20 units per cut.


Lime is another essential nutrient for good grass growth and proper efficiency of other applied nutrients.

The amount of nutrients in the soil that is available to the plant is influenced by having the pH of the soil at 6.3-6.5.

Take the opportunity during the summer when there are good ground conditions to get lime out where required.

Apply after silage or on grazed-out paddocks.

Do not apply on silage ground where you plan to take a second cut, as a lot of lime could well come back into the pit, affecting preservation and being no benefit to the field it was applied on.


Get slurry out early - don't run the risk of having full slurry tanks entering the winter period.

When the weather is good and ground conditions are favourable, target silage fields and fields that are low in P and K with slurry.

Don't wait for the weather to turn bad in the autumn.

Every 1,000 gallons of typical cattle slurry in the summer will be equivalent to a bag of 3/5/30.

Phosphorus and Potassium

A 'little and often' approach to applying P and K in summer can be good to increase P and K soil indicies.

Use your soil analysis to good effect in order to correct soil fertility levels.

Target low P, and especially K fields for extra P and K, for soil fertility build-up in the back end.

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