Permaculture Design/How to/Some ways to improve your soils
Traditional classifications of soils
- Colourless/white: high silica content
- Light/white: lack of oxygen; leached; high calcium; alkaline ph
- Yellow: lack of oxygen; high clay content; aluminium & iron
- Red: iron oxide
- Red/brown: volcanic basalt origin; iron & magnesium
- Black: rich in organic matter & nutrients; holds moisture
- Azalea, dandelion: acid soils; usually leached; often
- berries, conifers, dock: compacted with poor drainage
- saltbush, spinifex: alkaline; saline; dry soils
- nettles, clovers, vetch: excess nitrogen; low humus content; low microorganism content
- blackberries: open disturbed soil, possibly acid
- bracken: recent fire; general decline in soil fertility.
- buttercup: poor drainage, acid.
- thistles: low calcium & iron content; hard soils.
- chicory, chickweed, clover, groundsel: good fertility
parent material Eg soils derived from:
- Sandstone: sandy, high silica.
- Shale: clay; high silica & iron.
- Basalt: high iron & magnesium.
- Sour: Lacks oxygen, acidic, sulphur dioxide
- Sweet & earthy: high oxygen, good soil life & OM
- Garlic: arsenic in soil.
- Smooth & slippery: acidic, soil water lathers easily
- Weak soda: alkaline/mineral; won’t lather easily
- Worms: good moisture, OM, low pesticide residues
- Ants: drier, sandy
- Slugs & snails: damp, decomposing plant & animal material.
- Skinks & lizards: warm sunny, dry spots, good insect populations
- Run –off: is increased by bare ground, compaction, steep slopes
- Repels water: compacted, eroded, excessive use of dolomite, very little OM, sandy & allowed to dry out & has formed a moisture resistant barrier
- Shrinks & swells: high clay, holds water, cracks.
- Fast draining: hole filled with water, drains within 10mins: erodes easily, collapses easily, few fungal diseases, good movement of water & soil life. Not good for dams.
- Bare ground: agricultural or industrial contamination.
- Growth in poor soils:previous structures, compaction, old poultry or animal pen site
- No topsoil:quarry or fill site, erosion.
- Bad cracks & rubbish:old tip or landfill site
plants and soil minerals
Often plants which grow in deficient soils have the ability to concentrate those missing elements in their structure.
Potassium present ~ marshmallow, knapweed, wormwood, opium poppy, fumitory, tansy & borage. Deficient ~ red clover. Celery & leek like potassium. Chicory is potassium rich.
Calcium ~ buckwheat grown as a green manure or composted adds. Melon leaves are a source of it & oak bark is especially rich as are all thistles & willow. Dandelion “mines” it. Peas, beans, brassicas & turnips need it.
Phosphorous ~ bracken indicates a lack of it & accumulates it. Burn it & spread the ashes. Valerian & comfrey are rich sources. Whitefly indicates a deficiency along with magnesium. Brassicas need it to head well.
Iron ~ blackberry is a rich source.
Magnesium & sulphur ~ broom, salad burnett, plantain, & sheep sorrel (for magnesium)
Ragwort ~ copper
Thistles ~ nitrogen, copper & silicon.
Creating resources on your land
- Plant mulch making plants ~ comfrey, tree lucerne, grasses for hay, weeds such as dandelion, plantain, nettles, borage, deciduous trees.
- Use small prunings as part of the mulch around your trees. Place them over soil that you need to add organic matter like grass clippings, weeds, & manure on top & let nature do the rest. Once it’s reasonably broken down sow seeds/plant. Good way to establish areas for under-planting an orchard/food forest.
- Harvest local resources ~ bracken & chicory are high in potassium, add it to your compost, burn it & use the ashes around plants such as, celery & leeks. The brassicas (cabbage, cauli, broccoli, brussels) need phosphorous to head up well, comfrey & bracken supply it. Ragwort concentrates copper. Broom is high in magnesium & sulphur, lupins in nitrogen & calcium. Seaweed has many of the essential trace elements that plants need. Food scraps from cafes & super markets add to the mix for your compost.
- Plant wind breaks to filter air-born pollution and prevent soil erosion.
- Plant trees & shrubs to take up ground water pollution e.g. alongside a road, runoff from your neighbour who uses chemicals. The leaf litter from deciduous trees and shrubs also adds organic material to the top layer of your soils. Over time this will be a significant addition.
- Create wetlands planted with macrophytes (reeds & rushes) to take up the above pollution.
- Use raised beds for growing in.
- Seaweed, compost & dolomite help to clean soils of pollutants such as heavy metals.
- Allow weeds to grow ~ add OM, take up pollutants.
- Spread rock dust to supply minerals ~ basalt, granite, dolomite.
- Where practical, change the contour of slopes to create swales so that water does not run off as quickly and cause erosion.
- Don't leave bare soil, plant something instead -- or at least lay down some mulch.
- Remember that the more conditions you create for soil life to thrive the better your soils will be. Create diversity.