Organic soil care : Organic fertilisers - Mineral based products
Introduction
Composted plant wastes and manures, and green manures, are the main ways of adding plant foods to the soil. Organic fertilizers are only used where a soil or plant deficiency occurs which cannot be remedied otherwise - or where you are unable to make or obtain sufficient quantities of bulky organic materials.
Fertilisers suitable for use in an organic garden are of plant, animal or mineral origin. Most of them are waste products. The action of soil living creatures, or the weather, makes their nutrients available to plants, in a 'slow release' way. The mining and/or shipping of some of these products can have an adverse environmental impact, so think carefully before use.
Choose a product with a recognised organic symbol as first choice
Guidelines
Acceptable, but not for regular use
Commercial products
- Ground rock phosphate
- Aluminium calcium phosphate rock, where soil pH is > 7.5.
The cadmium content of the above materials must be no more than 90 mg per kilogram of phosphate. Use it as little as possible to avoid contaminating your land.
- Gypsum - Calcium sulphate
- Calcium carbonate of natural origin - chalk, marl, ground limestone*,
- Magnesium and calcium carbonate of natural origin - magnesian chalk, ground magnesium limestone (dolomitic limestone)*
- Rock dust/ stone meal, but only if a by product of the quarry industry.
Use to lower pH of a soil that is known to be too acid
Never acceptable in an organic garden
- Calcified seaweed
- Slaked lime
- Quicklime
- Soluble chemical fertilisers
- Guano, urea, Chilean nitrate
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Garden Organic is the working name of the Henry Doubleday Research Association (HDRA).
We are not responsible for the content of external web sites.
As far as pesticides are concerned, Lawrence D. Hills (who I first read 30+ years ago) recommended Derris and Pyrethrum. Why have these fallen out of favour?
(I must admit I only started vegetable gardening again last year, after a 20-year gap.)
This is a Pesticide Safety Directorate ruling.
Pyrethrum is still listed in these guidelines.
If you have queries about any other inclusions/ exclusions please do let us know.