Severn Waste Services and Mercia Waste Management

COMPOSTING - Greengrow

Properties of Greengrow

GreengrowWe call our composted product a soil conditioner rather than a compost, so as not to confuse it with branded growing media – mainly peat-based - that you see in garden centres.

Greengrow improves soil fertility; releases plant nutrients slowly and encourages vigorous plant root systems.

It is a good source of essential trace elements and supports the activity of soil micro-organisms that convert soil nutrients into forms available to plants.

Applications of composted green waste soil conditioner improve soil structure and its ability to hold water.

Laboratory studies have shown that it can give effective control of economically important crop diseases, such as club root on brassicas, white rot on onions, stem canker and black scurf on potatoes.

Typical properties of a composted green waste soil conditioner are shown below. For sources of further information see links below.

Properties of typical composted green waste soil conditioner

Nutrients (Total nutrient kg per tonne of moist compost based on typical analysis)
Nitrogen Phosphate Potash Magnesium Sulphur
as N as P2O5 as K2O as Mg as S
8.1 3.3 6.6 2 1

Potentially Toxic Elements - (Typical values compared with the Composting Association Standard for Composts)
Element Cadmium Chromium Copper Lead Mercury Nickel Zinc Units
Typical 0.71 19 45 108 0.17 18 186 mg per kg
Standard 1.5 100 200 150 1 50 400 dry matter

Other parameters

pH - Around 8.5 (Measures acidity)
Electrical conductivity - Around 770 mS /cm (Measures concentration of soluble salts)

Bulk Density - About 0.6 kg/litre or 1.6m3 per tonne

Loss on Ignition - About 20% (Measures organic matter content)

Carbon: Nitrogen (C:N) ratio - About 12

A good quality composted green waste soil conditioner will contain the odd piece of glass, plastic or other contaminants. These are likely to amount to less than 0.2% by weight in total.

The composting process should eliminate all weed seeds (measured as Viable Seeds or vs per litre). A count of 1 or 2 vs per litre is considered acceptable.

The availability of nitrogen in the product is relatively low compared to say animal manure, but this is important in areas of the country where groundwater is susceptible to infiltration of excessive nitrate (Nitrate Vulnerable Zones as expressed by the Environment Agency).


Severn Waste Services
The Marina, Kings Road, Evesham
Worcestershire WR11 3XZ

Tel: 01386 443376
Fax: 01386 446757
Email: enquiries@severnwaste.co.uk

Mercia Waste Management
The Marina, Kings Road, Evesham
Worcestershire WR11 3XZ

Tel: 01386 443376
Fax: 01386 446757
Email: enquiries@severnwaste.co.uk

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