12 March 1999

Slurry &manure are resources – not waste

In an attempt to change

attitudes to manure, MAFF

and ADAS are highlighting

its benefits and potential

cost savings on four farms.

James Garner reports

CUTTING fertiliser costs by targeting and using muck more efficiently is one way dairy producers can claw back margins and protect the environment.

This is the message from MAFFs Making the Most from Manure demonstration farm in Worcs where slurry and farm yard manure are being treated as resources rather than waste.

Resource management is not yet a buzz word in agriculture, but ADAS, which manages the demonstration farms on MAFFs behalf, hopes it can highlight the benefits of better manure application, analysis and use.

Reducing costs by using manure is the main priority, but this will tie in with environmental issues, says demonstration farm owner Tim Tyrrell.

However, his 180-cow dairy and 80ha (198-acre) arable unit at Berrowsfield Farm, Ingleberrow, has practiced good manure management for sometime.

"Last year we saved 20t of ammonium nitrate by using slurry more efficiently. Theres potential to save more by fine-tuning our organic manure use, and saving potash by using farm yard manure on potash deficient arable land.

"We havent dramatically changed what we normally do. However, we now know what we are applying by analysing the manurial value of slurry and FYM and how this matches crop requirements."

All the farms fields are soil sampled and tested once a year to find out how much residual nitrogen and minerals are present. Slurry is tested twice a year and at different depths in the lagoon.

"Knowing the analysis gives you confidence to cut-back on bought in nitrogen."

It also gives better results, says Mr Tyrrell. "The problem with working on average manure figures is that the nitrogen might not be available and you therefore dont get the crop production you expect."

This is the case at Berrowsfield Farm, as the slurry, separated and stored in a clay-lined 5600cu m (1.2cu m gal) lagoon, is not as high in N, P and K as average figures would suggest (see table).

But as the farms self-employed dairy manager Chris Cooke explains, the amount of total nitrogen available would be much as expected. "Organic manure is releases nitrogen slowly because it is broken down by soil bacteria over a year of more."

Using soil and slurry analysis means crop requirements can be met accurately. For dairy pastures, which require lower levels of potassium and potash, slurry from the lagoon is pumped through an underground main or umbilical pipe. "This slurry matches grass requirements," says Mr Cooke.

This year, more solid fertiliser will be spread on outlying arable fields with low potash indices. "This should raise potash levels, improve resource targeting and hopefully save on potash expense," says Mr Tyrrell.

At Berrowsfield Farm, application timing is helped by being able to split liquid and solid manure with a separater. This enlarges storage capacity meaning it can be stored until best applied, says Mr Cooke. "We can spread slurry when it can be used rather than when we cant store it anymore."

This means spreading slurry when the grass is growing, so reducing nitrogen leaching. "We normally spread slurry over all grassland in mid-February, then only on silage ground after the first cut and again after second cut."

To cut losses at application, Mr Tyrrell will make greater use of a trailing shoe applicator this year. "We usually apply slurry using a fish tail which sprays it on fields in relatively large droplets. But on windy days it skews the spray from its target to other areas."

A trailing shoe, either on the back of a tanker or attached to a hose, will place liquid under leaves on to soil, so stopping any slurry taint on grass which cows otherwise wont eat. This also reduces ammonia losses to the atmosphere, improving nutrient use and absorption, he says.

Other considerations are the residual effects of organic manure. Fertiliser budgets can help target applications and reduce wastage. "We use the ADAS-developed MANNER software program which looks at availability of fertiliser from previous cropping, annual rainfall and farm location.

"The program specifies what is available for use this year from last years applications, helping us plan our fertiliser and manure budget for this year," says Mr Tyrrell.

Berrowsfield Farm manure analyses* v typical averages

Nutrient (kg/t or m3) Yard FYM Separated Slurry

Farm Average** Farm Average**

Dry matter (%) 23 25 3.6 4.0

Nitrogen (N) 5.5 6.0 2.5 3.0

Phosphate (P2O5) 2.2 3.5 0.9 1.2

Potash (K2O) 5.4 8.0 2.5 3.5

* Manure sampled Feb 1998. ** MAFF/ADAS figures.

RESOURCEMANAGEMENT

&#8226 Nitrogen availability?

&#8226 Reduce bought-in nitrogen.

&#8226 Better application.