Muck – if you smell it, youre wasting it…
is becoming part of farmers
day to day lives. But MAFFs
Making the Most out of
Manure programme shows
how this can save producers
money as well.
James Garner reports
WHAT was once a waste product – muck – is now a highly sought after form of fertiliser. But the characteristic smell that pervades arable farms in autumn is a give away, demonstrating that much of its goodness is being lost to the atmosphere. Ammonia is evaporating and taking with it the nitrogen it was being spread for, warn experts.
MAFFs series of demonstration farms across the country as part of its Making Money out of Manure programme highlights how producers can benefit both the environment and their pockets by adopting environmentally friendly practices for muck.
Improving the environment is a collective responsibility, says ADAS project officer Neil Watson. "Its about improving the present systems of muck use and using livestock manures more efficiently."
The equation is simple. The more you get from muck the less valuable nutrients escape into the atmosphere, he says.
At Highlands Farm, Rettendon, Essex, David Chennells has 445ha (1100 acres) of heavy clay soil and 95,000 laying chickens. His egg operation employs 22 staff and involves packing and grading all eggs as well as rearing replacement pullets.
As a large arable unit as well, the chicken muck has always been spread on the farm, which grows mainly first and second wheats and oilseed rape.
"Weve been doing various forms of nitrogen testing for over 20 years, but have had problems with too much muck being applied and then having flat corn later in the year," says Mr Chennells.
In the past, contractors were used to spread muck but continual problems with laid corn prompted soil testing. This revealed too much muck was being applied given the high levels of residual nitrogen remaining in the soil.
Mr Chennells tried to get the contractors to spread muck more thinly. "But there wasnt really the machinery around then to do the job. So we bought a Bunnings spreader and decided to do it ourselves. Since then we have been able to get application rates down from 10t/acre to 4-5t/acre."
Better application is one way of improving muck use, but knowing the value of your muck is another, says Mr Watson.
"We analyse poultry manure because it is accumulated over a 13-month period in a deep pit litter system and so varies." Its a simple concept, he says. "You wouldnt buy blended fertiliser without knowing what is in it.
"By looking at soil mineral tests and cropping patterns we can build a picture to see what nitrogen is available to the crop and what the crop requires."
The manure budget can then be calculated using an ADAS software programme called MANNER. Where extra nitrogen is needed, bagged fertiliseris used.
Last year Highlands Farm saved £48/ha (£19/acre) in nitrogen, potassium and phoshate inputs by using Manner to determine what was available to the crop (see table).
But there are other complications at Highlands Farm 60%; of the cropped area of the farm lies within a nitrate vulnerable zone (NVZ), which means restrictions on spreading, timing and application levels.
To remain within the limit on organic manure applications an average of 210kg/ha (168 units/acre) of total N can be spread within the NVZ. Outside this area the Water Code recommends a maximum application of 250kg/ha (200 units/acre).
Currently one-third of the farm receives organic manure, but this area must be increased to 70% of the cropped land to meet NVZ demands.
• Application is important but so is incorporation. So the smell from chicken muck spreading doesnt offend local residents, Mr Chennells has agreed with his local council to incorporate it within 24 hours of spreading.
He uses heavy 4B Simba discs for the job and besides cutting smell concerns, it means less nitrogen is wasted to the atmosphere and is available for the crop.
The speed of manure incorporation and its effects on conserving readily available nitrogen vary for all manure types, says Mr Watson (see table 2)
• Application method.
• Nitrogen loss.
• Fast incorporation.
Table 2: Speed of manure incorporation to conserve readily available nitrogen
Manure type Conservation target
Slurry Immediate 6 hours
FYM 1 hour 24 hours
Poultry 12 hours 48 hours
Table 1:Cost savings from using MANNER
to determine nitrogen availability
Manure N kg/ha Standard Data Actual Analysis
autumn applied autumn applied
Applied on 15/8/98 15/8/98
Rate applied t/ha 14 14
DM% 30 31.4
Total N kg/t 15 15.9
Ammonia plus urecic acid 7.5 9.5
Total N 210 222
Potash available 126 150
Volatilised 10 13
Leached 39 50
N available for crop 75 87
N @ 20p/kg £15/ha £17
P 6.3kg/t 14t/ha 53kg/ha@27p/kg
assume 60% avail =£14/ha
K 11.1kg/t 14t/ha 93kg/ha@18p/kg
assume 60% avail =£17/ha
Total value £48/ha