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| Case Study 7 - Environmentally-driven,
reduced cultivation systems |
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Location |
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Central Leicestershire |
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Size, average field size and spread |
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2200ha; 10ha |
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Soils and landscape |
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The majority of soils suffer surface wetness caused
by dense slowly
permeable subsoils. Clay soils predominate (Denchworth and Hanslope
associations), the latter calcareous and developed in Chalky Boulder Clay.
Small areas of well drained, permeable medium loamy soils (Banbury
association) are included. |
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Cropping |
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60ha are devoted to field-scale trials involving
winter wheat, oilseed rape,
winter beans, set-aside and rotational leys. |
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Workforce |
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Trials and farm team. |
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Equipment and cultivation machinery |
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The trial has the benefit of access to machinery
used on the main estate as
well as machines provided by manufacturers as part of the experiments.
The seven fields used are around 10ha in size, but divided in half with
one
side adopting the cultivation practices typical of the main estate, while
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other side adopts a policy of reduced cultivation or direct drilling wherever
possible.
3.0m Rau Rotosem combined soil preparation and drilling. John Deere
750A No-Till drill, direct drill. 6.0m Vaderstad Rapide, combined cultivator
drill. 3.0m Simba FreeFlow cultivator drill. Simba heavy discs. Cambridge
rolls. Howard sub-soiler. 24m self-propelled sprayer. |
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Cultivation Policy |
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Traditionally the plough
has been the main tool used in seedbed preparation on the estate, although
there has been
a move towards reduced cultivation with the purchase of a cultivator drill.
The plough is still used exclusively going
into and out of the ley phase and to establish beans. Rape after wheat is
part- ploughed part reduced cultivation
while wheat after rape is established with discs and a cultivator drill,
as is wheat after beans. Current policy is to
drill as much as possible with the cultivator drill until soils become to
wet, finishing off with the plough. The reduced
cultivation sides of the fields are only ploughed, on average, once per
rotation (7 years). Wheat after rape and
beans is done with a cultivator drill with a stale seedbed prepared in advance
using heavy discs if the inter-crop
period is sufficient. Rape after wheat is established with a direct drill
into the stubble as is wheat after grass and
grass after wheat. Beans after wheat are direct drilled into a previously
disced and pressed seedbed, which has
been sprayed out with glyphosate. This minimises soil disturbance during
crop establishment and reduces
subsequent weed emergence. Spring weed control is obtained using a harrowcomb
weeder. |
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OSR 
wheat |
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Disc 
Roll; |
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Costings and Work rates |
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Operation |
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Cost (£/ha) |
Time taken (min/ha) |
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Ploughing |
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35 |
45 |
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Power Harrow combination |
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23 |
21 |
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Sub-soiling |
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32.6 |
67 |
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Drill |
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43.2 |
13 |
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Discs |
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22 |
12 |
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Rolls |
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8.4 |
8 |
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Direct Drill |
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43.2 |
13 |
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Sprayer |
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4 |
7 |
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Discussion |
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Decision to change |
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The trial was established in 1993 to evaluate the
economic performance, technical feasibility and
environmental impact of a less intensive farming system. In contrast to
other case studies, a strong
environmental focus was a key objective of the trials development. |
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How |
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Different cultivation machinery was supplied by manufacturers
to demonstrate the advantages and
disadvantages of the various established methods. |
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Benefits |
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The benefits measured are wide-ranging. It is important
to note that these have largely been achieved
without financial disadvantage to the system. With less passes there has
been less trafficking and lower
compaction. This has led to lower fuel consumption and less implement wear.
Conserving the organic
matter at the surface and reducing the exposure of soil aggregates to oxygen
has increased soil carbon
and soil nitrogen levels. This has improved the environment for soil fauna,
such as invertebrates and
earthworms. In one field, which has not been ploughed since 1992, earthworm
biomass has risen from
6g/m to over 1kg/m. This in turn reduces bulk density and improves structure
and drainage. There is
evidence of less sheet erosion because the organic matter provides a better-structured
soil surface,
particulate transport is reduced along with nitrate and phosphate losses
to surrounding water courses. In
the direct-drilled plot the presence of trash and stubble at the surface
during the winter months has been
shown to provide improved habitat for over wintering birds. |
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Problems |
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Drilled beans more accessible to rook predation.
Direct-drilled crops on clay soil do not receive a well
enough closed slot. Directly drilling small seeds after a trashy crop can
be problematic. Reduced
cultivation minimises the amount of N mineralised but this can lead to a
poorly developing crop. Slugs. |
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Solutions Found |
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Drill deeper (4cm), consolidate well. Protect
seed using a seed dressing, mix pellets with the seed, roll
after to close slot. Bale straw off, spread chaff well, roll after drilling
to increase seed to soil contact.
Apply autumn N, subject to SMN test, prevailing weather and conditions,
and crop appearance.
Consolidate, drill deeper. |
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SMI COMMENT |
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Range of equipment clearly
applicable for an experimental and demonstration farm,
whereas a single farm in a similar situation would need to decide the most
appropriate
set. Efficiency in crop establishment has been increased by approximately
60% using a
reduced cultivation system. |
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Soil Group |
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Type of Year |
M.W.D.s' |
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M.W.D.s' |
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Brockhurst
70% |
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Normal
Wet |
47
18 |
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5
0 |
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