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Nitrates Action Programme review: The Nitrates Action Programme review has resulted in changes which affect fertiliser rates for grassland farmers.

The availability of phosphate in manures for soils with a P index of 0 and 1 has been reduced from 100 per cent to 50 per cent for cattle and pig slurry and to 60 per cent for poultry and farmyard manures. This allows farmers who rely on livestock manures to more easily maintain soil P indices at optimum levels.

Soil analysis

Now is the last opportunity to carry out soil analysis before spring slurry application. Determining the soil nutrient status for phosphorus (P) and potash (K) by soil testing means slurry applications can be targeted to silage fields that have tested low for P and K.

The optimum indices of 2- or 2+ for phosphorus and 2- for potassium will maximise crop yield from the most economic use of inputs. Further applications of P or K to soils with above optimum indices are not cost effective and applications of phosphate above the recommended rates, in most cases, will be in breach of the nitrates regulations.  

Effective use of slurry

As a general rule for grassland farms, it is good practice to apply slurry to land that is used for silage. This makes best use of the nutrients in slurry and helps avoid nutrient shortfalls in the cutting ground. In grazing fields nutrients are recycled by the cattle as they graze. Thirty four cubic metres per hectare (3,000 gallons per acre) of cattle slurry supplies enough P and K for first cut silage (assuming soil indices for P are 2+ and K are 2-).

To get the best response from slurry and manure apply when grass is growing and try to avoid heavy applications in February.

AFBI research has shown that a splash-plate application of 45 cubic metres per hectare (4,000 gallons per acre) of cow slurry for a silage crop provides the same nitrogen (N) for grass growth as 2.5 small bags (50 kg) of 27 per cent N. Using a trailing shoe system instead of splash-plate to apply the slurry almost doubles the efficiency of N use, allowing a saving of another two bags of fertiliser per hectare.

When details of soil analysis results and previous cropping history are entered into the CAFRE Crop Nutrient Recommendation Calculator (available at HYPERLINK “” it calculates crop nutrient requirements whilst keeping within nitrate and phosphate regulations. This Calculator also takes account of the time and method of slurry application when calculating how much N to apply to first cut silage. Allow for improved N availability when deciding how much fertiliser to apply to first cut. There is unlikely to be a yield response to applying a total of more than 120 kg N per hectare for first cut.  

Typical February performance

How does your farm compare with the typical performance from the Co Armagh farms that I work with?

Average daily milk yield 24.2 litres per cow Average daily concentrate fed 8.6 kilos per cow Average daily milk from forage 5.1 litres per cow Average daily concentrate feed rate kilos per litre

Feed efficiency is critical at current milk price. The most important issue is to target concentrate feeding to those cows which need it most. Feed to yield cows calved more than two months over the TMR M+ at a rate of 0.45 kg per litre for the previous seven day average yield. The heifer M+ setting should be 2 litres less than that for cows. Silage quality dictates feed rate and therefore milk from forage. A number of farmers have been able to reduce the feed rate to 6.5 kg for the same level of performance by maximizing silage intake. This has resulted in feed savings of almost £350 per 100 cows per week. Monitor both milk protein content and body condition as these are early indicators of feed levels set too low against target milk yield.