2.1-2.7 and 3.5-3.10 cultural operations to produce food Flashcards
Describe:
Single and double digging and rotary cultivation
Single: Turning the soil over to one spade depth
Double: Digging out a trench to one spit depth and forking in well rotted OM to the depth of another spit
Rotary cult.: use of a machine which chops and turns over the top soil
Cultivation - timing
‘Cultivation window’ dependant on local climate and soil texture
Clay soils - in early autumn. Not too wet or too dry. Breaks up soil enabling frost to break up up large clods
Lighter sandy/silty soils - can be cultivated any time but avoid warm, dry conditions to avoid moisture loss, wind erosion and wet weather when rain can also lead to erosion and or capping. Light soils usually cultivated in spring prior to sowing/planting
Advantages of ‘no dig’
soil organisms not disturbed
weed seeds not brought to the surface
moisture loss is reduced (not lost through cultivation and retained through mulching)
Saves work and time
Less risk of soil pans, caps and soil erosion
Disadvantages of ‘no dig’
Pests/ eggs are not brought to the surface (eg slug eggs)
Perennial weeds may build up in the soil
Slow to remedy existing poor soil structure
Hard to apply to large-scale mechanised production
Cultivation window
Dependant on soil type, weather and local microclimates
clay soils - autumn, avoid when wet
sandy/silty soils - usually spring, but avoid dry sunny days to avoid erosion and moisture loss. Rain can also lead to erosion and capping
Advantages of ‘no dig’
Soil organisms remain undisturbed
weed seeds are not brought to the surface
Moisture loss is reduced (mulching and not exposing wet soil to evaporation)
Less work and time required
Avoids risk of soil erosion, cultivation pans and capping
Disadvantages of ‘no dig’
Pests/eggs are not brought to the surface
Perennial weeds may build up in the soil
Slow to remedy existing poor structure
Does not lend itself to large scale mechanised production
Define a bed system
Site is divided into narrow beds separated by paths, so beds are cultivated with no need to walk on them
Bed system - dimensions
Can be raised to a height of 15cm with wood, bricks or concrete blocks (or more informally, soil thrown up from paths in between beds in mounds)
Beds can be any shape but are typically 1.2m (max 1.5m) wide x 3m
Paths: minimum of 0.5m
Advantages of bed system
Lends itself to crop rotation
Avoids the need to walk on beds
Enables closer spacing of crops increasing yield
Can provide deeper top soil and improves drainage
Use of cloches and crop covers is easier (can also help warm soil)
Increases the cultivation window as plot is not walked on
Compost, manures and fertilisers can be applied to just areas where crops are planted
Lends itself to the no dig system
Disadvantages of bed system
cost and time in building and maintaining edging
Cannot use machinery
Not practical for mass production
The layout and use of plots is less adaptable
Perennial weeds and pests such as slugs can be hidden under edging and paths (difficult to remove)
Using greenhouses and cold frames
Benefits
Extends season by allowing for earlier sowing or extending growing season
Protects seedlings from pests and disease at a vulnerable stage
Early or late sowings of not fully hardy veg can be made in cold frames, GHs or later or earlier harvests
Also avoids pests and diseases (eg early carrots avoid carrot fly at the end of March through to May)
Growing early crops inside and others inside ensures continuity of supply (lettuce in GH for harvest in winter and spring and in situ from Spring for summer and autumn harvest)
Using low tunnels and cloches
These temporary structures can be used to warm up soil allowing for earlier sowing
Can provide some frost protection early and late in the season and securing earlier/later harvests (extends by 2 weeks at both ends of the season)
Additional warmth will speed up growth
Floating mulches
Define
Benefits
Example
Lightweight material temporarily laid over growing crop. Usually light and transparent - as crops grow the plants push up the material
Provide frost protection
Reduce cooling effects of wind
Can advance and extend harvest at both ends of growing season
Perforate polythene creates a greenhouse environment - protects from wind and traps heat from the sun. Edges secured by burying
Enviromesh
Define
Benefits
Very fine netted plastic
Benefits
A barrier for pests such as carrot root fly
Can also provide some protection against frost and wind
Mulches
examples and benefits
Dark coloured plastic polythene or ‘myex’ absorb heat and can be used to heat the soil prior to planting/sowing
Organic mulches also insulate the soil
Propagation methods
In situ - direct slowing in drills/ trenches and thinning
Sowing in situ is best for plants such as root crops that do not transplant well (carrots, beetroots - drills potatoes - trenches
Station slowing (runner beans)
Transplanting
A seed bed can be used for plants that transplant well, to maximise successional use of space (leeks, brussel sprouts)
Sowing under cover
This is appropriate for tender plants before outside conditions are suitable, and for plants or cultivars that crop better with higher temperatures, such as some tomatoes and cucumbers
Sowing into modules, seed trays, pots or blocks and hardening off (pots - courgettes)
Broadasting (green manures)
site options for sowing vegetables
3 options
Seed bed
A seed bed can be used for plants that transplant well, to maximise successional use of space
Under cover
This is appropriate for tender plants before outside conditions are suitable, and for plants or cultivars that crop better with higher temperatures, such as some tomatoes and cucumbers
In situ
Sowing in situ is best for plants such as root crops that do not transplant well
Successional sowing
- Sowing same variety at intervals to allow for longer harvest (radish)
- Sowing early and late varieties of a crop (pots, carrots)
intercropping
Growing a quick maturing crop in between slow growing cops eg, lettuce between brassicas or radishes between parsnips
Space so as not to deplete the main crop of resources
catch crop
Quick maturing crops that will be required for a later main crop eg, Radish, lettuce. Green manures can be used to enrich soil and keep it covered
Strip cropping
Cloches are moved between two or three strips of adjacent land so they cover three or four different crops at critical growth stages
Irrigation - critical timing
At the seedling stage
At flowering and fruiting
At transplanting
At regular intervals for root vegetables and leafy plants
Container types
seed tray - small/medium seeds for crops that cope with being transplanted (lettuce)
Modules - avoid root disturbance and space efficient
Pots - for plants with long propagation stage and for plants that are large when transplanted (courgettes)
Blocks - compressed coir - avoids root disturbance for large seedlings
Spacing - impact and optimum
Spacing influences size of crop and yield
Optimum spacing allows for:
- uniformity of growth
- maximum yield
- ease of management for grower
Spacing considerations
- Whether open plot or bed system (bed allows closer planting)
- Desired space of cops for eg onions, beets and carrots
- Soil quality - close crops suited to better quality soils with good reserves of nutrients and OM
- Availability of irrigation
- Weed competition - allow space to hoe on weedy plots
- Ability to control P&D or tolerance of P&D (faster spread among closely spaced crops
Factors significant to sowing
Timing
Preparation: digging, OM and fertilising
pH
Mulching
P&D protection
Irrigation
Spacing
