Properties Of Soil Flashcards
How is soil formed?
Weathering of parent rock
Addition of organic materials
Name the 3 ways rock weathers
Physical - heat cold rain etc
Chemical - water dissolves minerals
Biological - roots create fissures and dislodge Minerals also leave channels where water can travel and erode more rock.
Name the 4 horizons in the soil
Organic layer
Topsoil
subsoil
Parent rock
Properties of topsoil
Small lumps like crumbs Most soil organisms Most organic matter Dark - presence of humus Contains most roots Warmer
Define the term soil texture
The make up of the soil in terms of particle size e.g. The proportions of sand silt and clay
Particle size of fine sand
0.06-0.2
Particle size of silt
0.002-0.06
Particle size of clay
Less than 0.002mm
Describe characteristic of
Sandy loam
Feels gritty Good drainage Little water retention capability Little nutrient retention capability Quick to heat up No electrical charge
Describe the characteristics of a silty loam
Feels silky and soapy when wet
Fair drainage
No electrical charge
Describe the characteristics of a clay loam
Feels sticky when wet and hard when dry Poor drainage Good water retention Good nutrient retention Slow to heat up Negative electric charge
Describe the term soil structure.
How the components of the soil are combined (minerals, organic matter and humus) - arrangement of particles.
Describe key things crumb structure allows
Free water movement
Gaseous exchange
Through root exploration
Describe the ideal tilth
0.5-5mm aggregates.
Inside these crumbs are predominantly small pores which hold water and between the crumbs are macropores which contain air when soil is at field capacity.
What is saturation point
All pore spaces filled with water. No air present.
What is field capacity
Large pores have drained of water and small pores hold maximum amount of water held against gravity.
What is permanent wilting point?
Large and small pores are filled with air. Water held too tightly to soil particles to be liberated by roots. Plants will wilt and die.
Role of water in the plant x3
Provides transport for minerals and food through xylem and phloem
Provides structural stability for non woody parts of plant by filling vacuoles
Directly participates in chemical reactions in plants such as photosynthesis.
What is soil moisture deficit
Water that needs to be added to return soil to field capacity
Describe single digging
Digging to depth of 1 spit.
Dig out first trench put to one side.
Second trench then dug into first trench.
Repeat process until last trench then fill with soil from first trench.
How can root environment be improved and protected.
Cultivation - single and double digging, forking, taking, rotavating
Addition of organic and inorganic material
Managing soil water content - drainage and irrigation
Advantages and disadvantages of cultivation x3
Ad Prepares for planting Improves structure Exposes clods to winter weathering Breaks up pans Allows fertilisers to be incorporated Buries crop remains and weeds Dis Disturbs natural structure -earthworms etc Damages soil structure Dormant seeds may be brought to the surface Moisture may be lost from soil Hard work
Advantages and disadvantages of no dig
Ad
Preserves natural structure of the soil
Soil organisms not disturbed
Weed seeds not bought to the surface.
Less hard work
Bed system means harvesting can be done in any weather and drainage is improved
Dis
Pests may build up in soil
May be difficult to maintain fertility of soil
Fertility and structure not maintained in long term
Symptoms of poor drainage
Poor plant growth Water collecting on surface Soil constantly wet Mosses Blue/black colouring Smell
How to increase drainage in any soil
Add organic matter
Add lime
Why does adding lime (raising pH) improve drainage
Lime causes flocculation of clay particles.
This is where clay particles group together to form larger particles improving structure of soil and making it less dense.
What are some causes of excess water
Compaction of soil
Run off from patios and driveways
High water table
How to deal with excess water
Lay drainage pipes leading to a ditch
French drains to soakaways
Building raised beds
Appropriate planting
Methods of applying water
Watering can
Hoses
Sprinklers
Trickle lines or seep hoses
How to add water i.e. When and how much?
Apply in large quantities back to field capacity only
3 categories of organic matter
Dead organisms
Living organisms
Humus
How does addition of organic matter influence soil structure
Soil is physically opened up thus creating improved aeration
Improves water holding capacity - particularly humus
Source of nutrients as decomposes
Soil warms up quicker as humus is dark
Helps to form stable crumbs
Describe the characteristics and use for well rotted farmyard manure
Benefits and limitations
Good all year round conditioner Carbon rich Encourages earthworms Limits Must be well rotted Danger of pesticide residues Nutrient values vary widely depending on amounts of bedding incorporated
Describe the characteristics and use for garden compost
Benefits and limitations
Soil improver and mulch Basis of no dig systems Convenient Green - recycling and no need for transport Cheap Limits May contain pests, weed seeds and diseases Decomposition can take up to a year Some decomposition may be incomplete
Describe the characteristics and use for mushroom compost
Benefits and limitations
Raises pH - alternative to liming Soil improves Mulch or work in Good for brassicas Mushrooms pop up Relatively cheap Good soil conditioner Limits Not good for all plants due to alkaline Mushrooms pop up
Describe the characteristics and use for composted municipal/green waste
Benefits and limitations
Like garden compost
Can be mixed with coir etc to make good container compost
For soil improvement
Good soil conditioner
Recycled garden waste
High temperatures mean weeds pests and diseases killed off
Limits
May contain rubbish
High wood content so can have high carbon content
Describe the characteristics and use for Leaf mould
Benefits and limitations
Attractive mulch for ornamental horticulture Excellent soil conditioner Neutral pH or if pine acidic Limits Low nutrient content Small amount from large piles of leaves Slow process to decomposition
Describe the characteristics and use for chipped bark
Benefits and limitations
Mulch Looks natural under shrubs and trees Lasts a long time Weeds don't germinate in it. Various sizes Limits Robs soil of nitrogen Birds throw it around Slugs and snails lay eggs in it.
Describe the characteristics and use for composted straw
Benefits and limitations
Strulch (chopped straw) as mulch Light and easy to put down Knits together so doesn't blow away. Limits Low nutrient content Possible herbicide residues.
Describe the characteristics and use for green manure.
Benefits and limitations
Instead of mulch or compost
Provides improved soil structure, aeration, water holding
Adds nutrients especially nitrogen fixing
Weed suppressant
Protects from erosion
May provide flowers for pollinators
Limits
Hard work
Can encourage slugs
Can be difficult to get back to fine seed bed.
Purposes of mulching
Decorative finish Weed suppressant Moisture retention Protect surface of soil and from erosion Modifying soil temperatures
Names some non organic mulches
Minerals
Tumbled glass
Sheets such as polythene woven fibres
Conditions for successful composting
Air (oxygen) Water - not too much. Roof good Ratio of green to brown mix PH not too acid High temperatures Suitable heap size - right surface area to volume ratio
How to make a hotbed
Horse manure in container in winter 30cm
When it starts to give off heat cover with 15cm of soil
Plant into the soil
Gives off heat for a couple of months
How to make a wormer
Container with a tap and divided into 2 compartments separated by drainage plate.
Place kitchen waste into composter on top of drainage plate with brandling worms several 100
Worms digest waste and any liquid drains down and can be used as fertiliser
How to make comfrey or nettle tea
Place a handful of cut up comfrey leaves in a bucket. Cover with water and a lid Leave for 2-3 weeks (stirring daily) Dilute liquid 1-10 Comfrey rich in potassium Nettles in nitrogen
How would you use comfrey tea?
Liquid feed for fruiting plants
