COMPOST MULCH – MATURE APPLE
TREES BEAR FRUIT
Background
ReMaDe Kent and Medway is managing a
series of trials developing the use of
compost mulches with growers of fruit trees
in the region. The project, funded by WRAP
(the Waste & Resources Action Programme),
will be monitoring moisture retention; soil
improvement, shoot production, bud
development, and fruit quality and yield
throughout the 2006 growing season.
Various types of top fruit are grown on
approximately 9,000 hectares of land in
Kent – from apples and pears to plums and
cherries – all of which may benefit from
compost being applied to the soil before
planting and from compost applied as a
mulch around the base of the trees during
their life time.
The provision of adequate moisture at the
time of fruit development can have a major
impact on the eventual size of an apple.
For the grower, size is critical. A diameter of
60mm is needed and many supermarkets
will reject apples falling below this level.
Even small improvements per apple can
have an enormous impact on an orchard’s
overall profits.
Compost mulches work by allowing rainfall
to penetrate into the soil to the tree roots
whilst reducing the water losses from
evaporation from the soil surface. This
allows more water to become available to
the trees, reducing stress and improving
growth.
Compost mulch was sourced from three
major producers in the South East – Shelford
Composting Ltd. near Canterbury,
Beddingham Composting in East Sussex and
the Tree Fella in Essex. The compost mulch,
made from recycled garden waste,
conformed to BSI PAS 100. Mulch is
obtained when compost is screened to
between 15 and 40 mm at the end of the
eight to twelve week composting process.
This fraction, because of its woody nature,
has always been considered to be the most
difficult for compost producers to market.
The aim of the project was to evaluate all
aspects of the mulching approach – from
the production of the mulch fraction
through to delivery, application methods
and tree growth responses. Three sites in
Kent were used for this study.
Site 1 – Robert Balicki
Robert Balicki farms 100 hectares of top
fruit made up of 60 hectares of dessert
apples (Cox, Braeburn and Gala), 30
hectares of Bramley apples and 10 hectares
of pears (Conference, Comice and
Concorde). The soil type, although variable
on the Downs, is generally clay over flint.
He does not irrigate and has no plans at
this stage to invest in costly irrigation,
preferring to find alternative ways to use
rainfall efficiently. Robert has used straw as
a mulch in the past during the first year of
the trees’ life, although not on mature
trees. He agreed to try out compost mulch
and over two hundred tonnes was applied
in the late spring and early summer of
2005 to mature Gala trees. This was applied
as a one metre wide strip at a depth of
7-10 cms.
Site 2 – Ivan Clarke
Ivan Clarke has 36 hectares of top fruit
made up of 14 hectares of pears
(Conference and Comice) and 22 hectares of
dessert apples including 11 hectares of
Braeburn, 7 hectares of Cox, 2.5 hectares of
Regional Market Development Fund
2006
Gala and the rest of mixed dessert varieties.
His soil is a light sandy soil over chalk and
there is no irrigation on the farm. Straw has
been used as a mulch in the past but only
on young trees. Two hundred tonnes of
woody compost mulch, 15 to 40 mm
fraction, was applied in the early summer
of 2005 to rows of mature Gala trees in one
metre strips at a depth of 7-10 cms.
Site 3 – East Malling Research
East Malling Research Station (EMR)
provides horticultural research and
development for the perennial crops sector.
EMR boasts a 90-year history and worldclass reputation. A small trial was
established at the research centre with
compost mulch from Shelford Composting
Ltd. to assess the value of mulch on mature
trees. Three varieties are currently being
examined (Meridian, Saturn and East
Malling E11/20) using a randomised block
design with six replicates for each
treatment (with and without the application
of mulch). When the trial is complete later
this year it will provide statistically valid
results which can then be compared with
the large,
farm-based trials.
and wanted to see if the same was true
for mature trees. As the results here have
also been very positive, an even wider
market should now open up for the use of
this type of compost.”
According to farmer Robert Balicki: “The
application of compost mulch to the
mature trees was probably too late this
year for any real impact on yields. But if
the compost mulch has the same effect
on these trees in eighteen months time
as it has had on the young orchard, then
compost could have an important role to
play in the future.”
Key Benefits of using compost
mulch:
• Water is conserved in the soil
• Trees are less prone to water
stress
• Fruit size may be improved
• Yields may be increased
• Nutrients are slowly released
into the soil
Future findings
The project has raised awareness of the
benefits of using compost in fruit production
amongst growers within the region and is
on track to demonstrate that compost can
help retain moisture in the soil, thus
reducing the need to irrigate. It can also act
as a soil improver and potentially increase
yield and fruit size.
Dr Joe Lopez-Real, ReMaDe Kent & Medway’s
Organics Adviser said: “This exciting
project was set up in direct response to a
specific request from growers. They had
seen the positive results achieved by
replacing straw with compost mulch in
the establishment of young tree orchards
Contacts and information sources
Compost soil improvers and mulches of good quality, meeting BSI PAS 100, can be found by talking to ReMaDe Kent and
Medway or visiting the WRAP website. The Compost Supplier Directory can be accessed at www.wrap.org.uk/organics.
A final report from this project will be also made available on the WRAP website.
WRAP
The Old Academy, 21 Horse Fair,
Banbury, Oxon OX16 0AH
Tel: 0808 100 2040 Website: www.wrap.org.uk
ReMaDe Kent and Medway
C/o Invicta Innovations, East Malling Research,
East Malling, Kent ME19 6BJ
Tel: 01732 876617 Website: www.remade-kentmedway.co.uk
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