background image
Guide 20
Slurry management technology
There has been a significant increase in interest among
farmers in overall slurry management and making maximum
use of the nutrients available. This has been fuelled by:
income pressures on farm, farmers wanting to get
the most from slurry on farm and reducing the use of
purchased fertiliser;
slurry equipment grants for tankers and applicators; and
farmers being educated about the value of applying
slurry correctly at the best times and using the best
There are three key steps involved in slurry management:
Slurry preparation
When slurry is in the storage tank, over time the solids
and liquids separate, leaving the liquids at the bottom
and dryer material at the top. It is paramount to mix these
properly prior to application to maximise the nutrient
value of the slurry and increase accuracy of spreading
over the application width. Abbey Machinery's Tornado
3000, 4000 and 5000 high-pressure agitation pumps
and Contractor Rapid Pump carry out this mixing rapidly
and e ciently. When agitating slurry, it is important to add
water back in to improve mixing. This also aids ammonia
uptake when spread, although, the added water does
dilute the P and K content. When agitating slurry, it is
paramount to take every precaution to avoid the potential
dangerous gases involved when mixing slurry.
Slurry application technologies
Splash plate is still the most prevalent application medium.
It is becoming increasingly more popular to spread slurry
through applicators (Abbey Machinery Tri-App, Trailing
Shoe or Shallow Injector). Some of the key benefits of
using applicators are that they: deliver the nutrients
directly to the root zone; reduce ammonia emissions by
up to 90 per cent; preserve the soil structure; reduce
odour emissions; and reduce soiling of grass which
reduces rotation length when grazing. The main criteria
for determining the optimum applicator required include:
soil type clay, loam or stony; crops grass or cereal;
landscape level or hilly; slurry tanker standard, recess
or tandem; tractor horsepower (HP) available; legislation
in relation to application methods, timings of applications,
road safety transportation etc.
Minimising soil compaction
Compaction to the top soil and upper subsoil typically
takes one to five years to repair depending on the severity
of compaction. Lower subsoil compaction can take from
five to 10 years to recover. For these reasons, farmers are
getting more conscious of soil compaction and are looking
for ways to minimise it. Wheel choice has a major bearing
on potential compaction of both top- and sub-soil. In
general, low ground pressure tyres can be used to reduce
the potential for compaction. Wheels with larger radii
(longer rolling circumferences) and greater width all have
the potential to reduce the impact of the machines on the
soil. Bigger slurry tankers and higher horse power tractors
require the correct wheel specification to minimise their
impact on the ground.
Abbey Machinery technology caters for the `total cow'
from one end to the other. It works closely with customers
listening to their needs to develop machines with the required
specifications to suit their particular soils, tractor HP, field-
aspect and working conditions. With more than 35 high-
specification slurry tanker models in the Abbey Machinery
range from 900 gallons to 6,000 gallons both farmers and
contractors have lots of choice.
High fertiliser prices are increasing the value of slurry.
Typically 1,000 gallons are worth 25 (85 per cent of this
is from P & K values).
It is best to carry out soil tests to identify fields low in P &
Costs savings can be made by using slurry to replace or
complement fertiliser on farm.
Savings are maximised when slurry is applied in
accordance with the crop needs, and applied through an
Applicator that maximises the plant availability of N. It is
best applied under cool, moist, overcast conditions.
Michael O'Grady and Tony Galvin, farm manager,
Almarai Farm in Saudi Arabia.