2.The Root Environment Flashcards
1
Q
What is primary cultivation?
A
The preparation of soil for sewing or planting, involves the turning over of the soil
- Single and double digging by hand
- Mechanical ploughing and subsoiling
- Rotovating
2
Q
What is single digging?
A
The first operation in the preparation of a seedbed
- Mark out a rectangular plot
- Mentally divide it into two strips
- Dig a small trench, 30cm wide, and a spade’s depth (spit), from the end of the first strip
- Place this soil to one side leaving the first trench empty
- Dig the second trench and move the soil into the first trench
- Repeat until last plot is filled with the soil from the first
- Organic matter can be incorporated
- Weed seeds should be removed
3
Q
What is double digging?
A
Needed o soil which has not previously been cultivated, there is a soil pan or soil is heavily compacted
- Prepare as per single digging but to depth of 2 ‘spits’ rather than 1
- Do not mix top soil and sub soil
- Remove soil from upper/lower spit of first trench and the upper of the second
- Lay aside in clearly marked piles
- Soil can be moved from lower of second trench to the bottom of the first
- Then the top of the third trench can be moved to the top of the first
- Repeat until last plot is filled with the soil from the first
- Organic matter can be incorporated into bottom spit
4
Q
What is rotary cultivation?
Why do it?
A
Can be used for:
- Covering larger sites
- With different attachments they can be used for primary and secondary cultivation
- They reduce the time it takes to cover a large area. However, they can cause problems in relation to compaction with the creation of soil pans due to cultivation
- Avoid wet or dry conditions to prevent damage to the soil structure
Can be used to:
- Prepare tilth for sowing
- Incorporate green manures
- Control annual weeds when preparing a seed bed
5
Q
What are the processes of secondary cultivation?
A
- Forking – to depth of 10cm, less harmful to structure than spade as breaks follow naturally existing fracture lines. Can be used on boarders with established plants where soil can not be dug over
- Consolidation - treading or roller, walking over the area using flats of feet. Removes larger pore spaces and encourages water to be drawn up through the small pore spaces. Ensures seeds are in good contact with soil and that water is readily available
- Raking - Produces a fine tilth suitable for the seed to be sown. Used after digging/forking to level soil and remove stones
- Hoeing – in dry weather this can damage roots of plants
6
Q
Advantages of using rasied beds?
A
- Improving drainage
- Increasing soil temperature in spring
- Improving access
- No of plants per m2 can be increased
- Growing plants in a different soil type
- 1.2m wide with paths of 45cm between, up to 30cm high
- People are confined to paths between so chance of compaction if removed
7
Q
Why add organic matter?
A
- Improves soil structure and crumb formation
- Increases drainage and aeration
- Increases nutrients available to plants
- Helps the soil heat up quicker since the material is darker
- It will increase the activity of soil organisms
- In lighter, sandy soils is will bind particles together and improve water retention as well as preventing the leaching of nutrients
- In heavy clay soils it will form smaller aggregates and improve drainage
8
Q
Why add inorganic materials?
A
- Lime – used to in a clay soil to improve soil structure by forming smaller aggregates (will raise PH), gypsum or calcium sulphate can be used when raising PH is not an option
- Grit – For poorly draining soils to improve aeration
- Sand – can also be added to improve soil structure through improved drainage and aeration
9
Q
List factors indicting that soil is compacted?
A
- Heavy soils/ subject to a lot of wear
- Can be caused by people and machinery
- Most likely to happen when soil is cultivated at wrong time of year
- Slow drainage and increased surface run of
- Poor plant growth
- Bad smells/change in soil colour
- Soil is hard
10
Q
What are soil pans?
A
- Hard, impervious layers that form as a result of over cultivation with rotovators and/or mechanical methods due to the cultivation at the same depth over extended periods of time.
- Can occur at any level depending on the cultivation method
- More common in clay soils or soils that have a poor soil structure
- Acts like a barrier to plant roots
- Top soil likely to become water logged
11
Q
What is surface capping?
A
- Can occur on light soils or ones with fine tilth
- Loose, fine particles with low levels of organic matter form a hard, impervious layer, usually after hard rainfall.
- This cap or crust prevents the free movement of air and water and is damaging to plant roots and growth
- Prevents seedlings from growing
- Mulch can help to prevent
12
Q
How can soil structured be damaged by cultivation?
A
- Cultivating at the wrong time can cause soil structure damage
- Cultivating clay or silt soils can lead to compaction and destroy crumb formation
- Over cultivation such as forking, raking or overuse of mechanical cultivation methods
- Cultivating with rotovators over long periods of time can cause pans to form in the soil
13
Q
How to avoid or remove compaction?
A
- Addition of organic matter
- Mulches (e.g. leaf mould) can help prevent surface capping, soil erosion and leaching of nutrients
- Avoid use of heavy machinery
- Cultivate at the correct time
- Subsoiling - This involves specific tools that are attachments to tractors or pedestrian operated machines. Winged tine, pulled through soil
- Single/ Double digging
14
Q
What causes excess water?
A
- Hard, impervious rock close to the soil surface. This prevents the percolation of water down and causes a high water table.
- Compaction will also cause bad drainage either as standing bodies of water or as surface water run-off
- Topography can also affect a soil’s ability to drain. Water will often accumulate at the bottom of a slope.
- High volumes of surface run-off water can occur when the is a high presence of impermeable materials such as paving (e.g. patios), tarmac or concrete
15
Q
How do you get rid of excess water?
A
- Normal cultivation methods should be considered first - double digging/sub soiling, add organic matter
- Soakaway – deep holes filled with rubble that penetrate to porous rocks, allowing water to filter through it
- French drain – a gravel-filled trench lined with landscape fabric to keep soil and silt out of the gravel.
- Raised bed - filled with imported top soil, organic matter and grit
- Appropriate planting – plants that can cope with waterlogged and marginal conditions
