Dairylink: Time to think about slurry as ban lifts for the Northern half of the country

28th January 2016

Dairylink: Time to think about slurry as ban lifts for the Northern half of the country

Despite the wet and waterlogged fields, Conail Keown advises that it's time to think about slurry for dry paddocks.†

Chemical fertiliser costs account for approximately 1.5p to 2p/litre on Dairylink project farms, with the exception of some farms that required additional compound fertiliser for certain paddocks.

Typically, these farms required 20:10:10 compound, or in some cases 0:46:0, to address deficiencies in phosphorus (P) and potassium (K) nutrients in the soil, which increased chemical fertiliser costs by a maximum of 0.5p/l.

The key point here is that fertiliser is a good investment on your farm and would need to double in price to become as significant as concentrate costs on many farms.

However, compound must be targeted at the correct area. All project farms used soil analysis to identify deficiencies in soil nutrients last year. This information is still valid and areas not corrected last year with additional nutrients can be focused on this year.

Maximise slurry use

Slurry storage on project farms is near its capacity and persistent wet weather will make it difficult to get slurry out once the spreading ban has been lifted next week.

In some cases, slurry will need to be transferred between tanks just to hold off on spreading on what can only be described as extremely waterlogged land.

Another issue on top of finding a dry field will be finding a field without too much grass. Some of the project farms have carried high covers through the winter, so ideally these paddocks will have to be grazed before slurry can be applied.

Last year, Kevin McGrade, Dromore, Co Tyrone, had a good response to slurry spread on paddocks after the first grazing and will adopt the same approach this year.

Robin Clements, also in Tyrone, says his ground is very wet and it will be a long time before slurry can be applied to get the full benefit from it.

Robin uses an umbilical system to get slurry out and says that its light weight on the ground allows him to get out early. However, land is still waterlogged and too wet for a slurry application.

Robin will have to target some dry fields with slurry just to ease the pressure on storage over the next fortnight, but spreading on silage ground will have to wait for conditions to improve.

Value of slurry

Organic manures are a valuable source of nitrogen (N), P and K, and can effectively replace chemical fertiliser in spring.

Therefore, targeting slurry spreading in the early spring is a cost-effective way of replenishing soil fertility.

Nigel Corbett, Banbridge, Co Down, intends to target his outlying farmland with slurry this spring. This land rarely receives organic manure, because it is approximately three miles away from the main farm and is mainly used for replacement heifers.

However, soil analysis has indicated that this outlying farmís soil has P and K indices of 1 and 2, which is well below the level required for optimum grass growth, and consequently the decision has been made to spread slurry there this spring.

A splash-plate application of 45,000 litres per hectare (4,000 gal/acre) of cow slurry in February will provide the same N for grass growth as two and a half 50kg fertiliser bags of 27% N.

Furthermore, by applying this slurry with a trailing shoe rather than the more traditional splash plate, the slurry will almost double the efficiency of N alone, allowing a saving of another two bags of fertiliser per hectare.

In this specific case, Nigel has established that his total P and K requirement can be met with nutrients from the slurry, which gives a significant financial saving in purchased chemical compound fertiliser. In simple terms, he will only have to purchase chemical fertiliser (27:0:0) to deliver his N requirements.

The farm nutrient calculator (available by clicking here) takes account of the time and method of slurry application when calculating how much fertiliser N, P and K to apply.

Index 3 is optimum

The optimum target for soil P and K is index 3 in ROI and index 2 in NI using the Olsen P test.

Replacing nutrients removed by grazing or harvested grass to maintain an index of 3 will ensure optimum growing conditions for the grass plant.

Soils at index 1 and 2 for P and K have a lower nutrient supply, so require additional nutrients every year to reach soil index 3.

Research conducted by Moorepark has shown that soils at index 3 for P and K can produce an extra 1.5t/ha of grass dry matter over soils with index 1 for these nutrients.

This is equivalent to 15% more grass production on many farms across the country, which can represent a significant saving in concentrate costs on farms, once this grass is utilised correctly.

This article has been reproduced with the kind permission of the Irish Farmers Journal. Please click on the below Irish Farmers Journal logo to be brought to additional dairy articles

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