soil cultivation and water management

1. RHS Level 2
Certificate
Year 2 Week 3 – cultivation and soil
water management

2. Quiz
 Tests last two week’s material.
 15 minutes, test conditions.

3. Quiz Answers
 Surface capping arises when the particles in the soil
(particularly in silty soils) bond together. This means that
water cannot soak into the soil and air cannot enter. This
prevents seedlings from breaking through the soil
surface. It also means that roots cannot get the oxygen
they need to respire.
 Cultivation pan may either be made up of iron leached
from the top soil and bonded to clay particles, or of stones
that have settled out of the top soil during cultivation.
This prevents the roots of plants from penetrating into the
sub soil and may lead to poor establishment. Cultivation
pan may be rectified by double digging

4. Quiz answers continued
 Question 2 – (a) and (c)
 Question 3 – (c)
 Question 4 – (a)
 Question 5 – Sandy soil
 Question 6 – 40% sand, 40% silt and 20% clay.
 Question 7 – (b)
 Better than 3 or 4 out of 7 is a good result at this
stage. Less than that you need to review your
notes again.

5. Learning Outcomes
2.4 State the purposes of primary and secondary soil cultivations, including the
addition of soil conditioners.
2.5 Describe the benefits and limitations of basic cultivation techniques.
2.6 Describe the use of pedestrian operated soil cultivating machines
2.7 Describe the management of minimal cultivation systems e.g. no dig systems.
3.6 Describe two methods by which soil structure can be improved and two
practices which damage soil structure, to include: incorporation of organic
matter; addition of inorganic soil improvers; compaction; and cultivation
techniques.
3.7 State what is meant by ‘surface capping’; explain how it may happen and what
effects it can have on plant establishment and growth.
3.8 Describe how a cultivation pan can be formed, what effect it has on plant
growth, and how it can be rectified.
4.4 Identify a range of management techniques for maintaining soil moisture at
appropriate levels
4.5 Identify the surface symptoms of poor drainage, to include: standing water,
surface run-off and indicator plant species.

6. Cultivation types
 Primary cultivation – digging (single or
double), ploughing or rotavating.
Aerates the soil; incorporates organic
matter; buries weeds and crop waste;
exposes pests and allows weathering.
Starts to break down large aggregates

7. Cultivation types
 Secondary cultivation. Includes forking over,
raking, treading to firm the soil and harrowing.
Done after primary cultivation.
 Produces a fine crumb-like structure
 Firming allows good rooting by reducing large
voids in the soil into which roots may grow
and die off.
 Levelling prevents run off of water and
therefore erosion of fine soil particles.
 To incorporate dry power or granular fertilizers
evenly into the soil by raking.

8. Cultivation techniques
(primary)
 Single digging – used for previously
cultivated soil with good structure.
 Double digging – for uncultivated soil or
to improve clay soils or those with
cultivation pan, poor drainage etc.
 Rotavation – for larger areas. Safety
considerations – PPE, maintenance,
correct operation.

9. Benefits and limitations -
digging
Benefits Limitations
Improves the structure of the soil –
allows access for water and air
Disturbs natural structure of the soil and
may harm beneficial organisms
Exposes pests to predators and the
weather. Allows clay clods to be frosted.
Can damage soil structure if the texture
and wetness of the soil are not taken into
account.
Breaks up cultivation pans and improves
drainage.
Brings dormant weed seeds to the
surface where light will stimulate
germination
Incorporates organic matter and buries
crop residues and weeds
Leaves a bare surface which may lead to
leaching or capping

10. Benefits and Limitations -
Rotavation
Benefits Limitations
Less hard work than manual digging Expensive to buy or hire, safety
considerations.
Makes larger areas more manageable Can produce a very ‘fluffy’ tilth with large
air pockets – will need raking and
possibly firming before planting
Provides a good tilth in a short period of
time
Will not effectively break up hard or stone
pan and may cause a cultivation pan by
smearing wet clay soils.
Has most of the benefits of single
digging.
Not ideal for incorporating organic matter

11. No Dig Systems
Benefits Limitations
Less work than traditional digging
approaches to soil management
Will not remedy soil structure problems
like hard pan or poor drainage
Does not damage soil structure where
this is already good
Large amounts of organic matter are
required
Weed seeds are not brought to the
surface
Some risk of long term soil acidification
– which reduces beneficial organisms
Soil organisms are not disturbed Pests may build up in the soil as the
larvae are not exposed by winter
digging

12. Drainage
 Symptoms of poor drainage – standing
water; gleys; indicator plant species
(rushes, docks, creeping buttercup,
horsetails); surface run off.
 Cures – double digging; incorporate
coarse organic matter; install tile drains or
sub-soiling (clay soils) on large areas.

13. Water retention and irrigation
 Irrigate to restore capillary water – so add enough to
do so when needed rather than water little and often.
If water does not infiltrate the root zone it is of little
use to plants.
 Mulches and timing of irrigation can reduce
evaporation. Mulches must be applied to moist soil.
Water at the roots – not on the leaves and bare soil.
 Organic matter acts like a sponge and creates
aggregates with both intermediate and macro pores.

14. Learning Outcomes
2.5 Describe the benefits and limitations of basic cultivation techniques.
2.6 Describe the use of pedestrian operated soil cultivating machines
2.7 Describe the management of minimal cultivation systems e.g. no dig
systems.
3.6 Describe two methods by which soil structure can be improved and two
practices which damage soil structure, to include: incorporation of organic
matter; addition of inorganic soil improvers; compaction; and cultivation
techniques.
3.7 State what is meant by ‘surface capping’; explain how it may happen and
what effects it can have on plant establishment and growth.
3.8 Describe how a cultivation pan can be formed, what effect it has on plant
growth, and how it can be rectified.
.4.4 Identify a range of management techniques for maintaining soil moisture
at appropriate levels
4.5 Identify the surface symptoms of poor drainage, to include: standing water,
surface run-off and indicator plant species.