| Grassland
Spotlight on soils at Grassland & Muck
Compaction is a serious problem in many grassland soils, but attempting to cure it could be hazardous if the
underlying drainage is failing, experts have warned.
round 70% of UK
pasture is suffering
from degradation,
with 10% severely
compacted,
leading to poor
grass yields and limiting access to
land following rainfall. However,
farmers who are considering
alleviating such compaction
should check the field drains are
working first, or they could be
wasting their time.
A
“The most common problem
with drainage systems is when
the outfalls aren’t kept clear –
so dig out your ditches and
check for running water from
the outfalls after rainfall”
According to ADAS experts who
will be running the soil and nutrient
advice clinic at this year’s
Grassland & Muck Event,
productive soils need to be both
well drained and well structured;
the two are closely interlinked. “I
www.farmingmonthly.co.uk
go to many sites where people
have enough or even more
drainage than they really need, but
the soil is too compacted for water
to pass through to reach the
drains,” says Kirk Hill, drainage
specialist at ADAS. “On the other
hand, there is no point subsoiling
if the drainage isn’t working; you
could cause more damage than
you relieve.”
The key is to identify where
there may be soil or drainage
problems, and then take the
correct action to alleviate them.
Signs of compaction or
inadequate drainage can include
standing water, weeds and poor
yields, so farmers should dig a soil
pit in these areas, says soil
specialist Dr Paul Newell-Price.
The pit should be at least 60cm
deep, and farmers should then
look at the soil structure and
colour as well as root depth and
presence of earth worms.
To learn more about such tell-
tale signs, visitors to the Grassland
& Muck Event will be able to get
below ground level in the soil pit,
to examine the soil profile and
identify problem areas. “Half of the
soil pit will have been compacted,
and visitors can also see a sward
lifter, aerator and drum-type
loosening equipment in situ, to
find out at what depth they work
best,” says Dr Newell-Price.
In addition, visitors can bring a
photo of their own soil profile and
a soil sample to discuss with
ADAS experts (stand 906), as well
as recent soil and manure analysis
results.
Around 6.4m ha of agricultural
land in England and Wales has
been drained with pipe systems in
the past, but many have not been
maintained and about 60% of soils
would benefit from repairing or
replacing the drainage, says Mr
Hill. Many farmers will hold historic
drainage plans, or may be able to
access them through the local
drainage contractor, but where
they are not available the best
option is to look at aerial photos,
walk the field, and clear drainage
ditches to look for outfalls.
“The most common problem
with drainage systems is when the
outfalls aren’t kept clear – so dig
out your ditches and check for
running water from the outfalls
after rainfall,” he explains. “It may
be that you only need to replace
the final metre or two where the
outfalls have silted up or
collapsed.”
Different soils have different
drainage needs – which will also
depend on the average rainfall in
the area, says Mr Hill. “However,
changing weather patterns have
put the spotlight back on drainage.
We’re getting more intensive
storms, leading to increased risk of
soil erosion and loss of soil
organic matter. Better soil
management and drainage will
reduce these losses and result in
less soil drought, waterlogging
and nutrient loss.”
The value of well drained, well-
structured soils is considerable,
adds Dr Newell-Price. “Healthy
soils will be more resilient to
adverse weather, produce higher
yields, and have a longer grazing
season. You’ll also have better
uptake of nutrients and more
timely field operations. Everything
starts below ground – if you don’t
get your soil right your seeds and
other inputs will be wasted.”
May 2017 | Farming Monthly | 25