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| Case Study 10 - Plough/power harrow system
on an arable livestock farm |
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Location |
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Devon |
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Size, average field size and spread |
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205ha (70ha redland 135 heavy Dunland over Culm Measures) |
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Soils and landscape |
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The red, gritty Crediton series soils are easily
worked and do not poach,
however they are droughty in dry summer weather. They contrast with the
clayey Hallsworth and Halstow soils, which grow heavy grass crops, but
which poach readily and are difficult as arable soils. Rainfall averages
about 900mm a year, with autumn and winter typically the wettest seasons. |
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Cropping |
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Cropping involves 59ha of arable (all but 25ha on
the Redland) given over
to silage maize, 146ha of permanent grass and 52ha of leys. Slurries and
manures from the 300 strong dairy herd, plus followers, are spread mainly
on the Redland maize stubbles and grass fields on the Dunland, in
accordance with the farm’s waste management plan. |
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Workforce |
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Although run as a family farm, contractors carry
out a proportion of the
spring cultivations, all of the maize drilling and harvesting, and
increasingly slurry application using umbilical spreading. |
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Equipment and cultivation machinery |
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Plough; 3m Kuhn power harrow; John Deere 120hp
tractor. Contractors
either 3 or 4m power harrow and 12 row combination drill. Harvesting by
contractors.
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Cultivation Policy |
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Procedures are tailored
to the different soils. Maize harvest is followed by subsoiling, if ground
conditions allow.
Because maize harvest rarely takes place with dry soil conditions soil damage
is to be expected. This can encourage
runoff and is also a reason for the importance attached to subsoiling. On
the Redland autumn ploughing follows
immediately after slurry spreading on the maize stubbles, particularly on
fields where winter runoff has been a
problem. Any Redland unploughed in the autumn is left until March when slurry
is applied prior to ploughing. All
the maize land is then power harrowed, twice if needed, followed by drilling.
Often autumn conditions rule out
ploughing on the Dunland, although that is the preferred option. Spring
ploughing of these difficult soils is
commonly followed by Cambridge rolling, prior to power harrowing and drilling. |
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Crop sequence |
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Operation |
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Output (ha/hr) |
Cost (£/ha) |
Time taken (min/ha) |
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Ploughing |
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0.6 |
39 |
100 |
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Rolling |
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3.5 |
7 |
17 |
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Power Harrow |
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2.3 |
18 |
23 |
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Drilling |
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2.5 |
23 |
24 |
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Subsoiling |
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1.6 |
20 |
28 |
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SMI COMMENT |
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A plough is required on
this soil type to take out old grass prior to reseeding. The success
of the maize crop favours a plough-based system with the establishment of
a good
seedbed and nutrient release after frosting. A power harrow is required
for spring
cultivations, when autumn ploughing is not possible. Slurry disposal to
stubble during
winter and spring is a risky practice due to leaching and runoff and the
soil compaction,
which may occur. Application to top leys where available may be more appropriate.
In a
true mixed farm situation where cereals and break crops are grown, it is
likely that the
farm would continue to use same power harrow combination unless reduced
cultivations
were contracted out. Spring machinery workdays are very limited and soil
damage in this
system is more than likely to occur even in a normal year. |
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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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Crediton |
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Normal
Wet |
76
52 |
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22
0 |
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Halstow
Halssworth |
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Normal
Wet |
26
2 |
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2
0 |
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