A testing programme to analyse composts and growing medias for their nutrient content is available.
About this Testing
What are Composts and Medias
Compost is a material added to a soil as a mulch or soil conditioner to add valuable soil organic matter. Composts are often dug into the soil to improve soil drainage, aeration and nutrient holding ability.
Soil-less growing media are used directly as a complete growing media for the plants to grow in. Likely ingredients of soil-less growing medias are fine bark or peat with pumice or untreated sawdust with slow release fertilisers. At Hill Laboratories, materials other than growing media will be regarded as composts.
Please Note: Other than Dairy effluents, raw manures are not accepted by the lab.
Summary of Compost Tests
The most commonly asked questions about composts are: ‘What nutrients are in it?’; or, ‘Can I use it as an organic fertiliser?’ We have established a series of test profiles that are useful to evaluate compost quality.
Compost Testing Options
- Basic Compost Profile (BC)
Dry Matter, N, P, K, S, Ca, Mg, Na, Fe, Mn, Zn, Cu, B, OM, C:N Ratio
Dry Matter, N, P, K, S, Ca, Mg, Na, Fe, Mn, Zn, Cu, B, OM, C:N Ratio, Cd, Cr, Pb, Ni, Hg, As
Basic Compost Profile (BC) + WEB Profile
Dry Matter, C, N, C:N Ratio
- Heavy Metals Profile (HC)
Cd, Cr, Pb, Ni, Hg, Zn, Cu, As
- Pesticides Screen Multi-residue
Testing of >180 organo-nitrogen, organo-phosphorus and organo-chlorine Pesticide compounds including DDT
- Acid Herbicide Screen (Acidherb) Profile
2,4-D, 2,4 5-T, Triclopyr and other acid herbicides
- Water Extractable A (WEA) Profile pH, EC
- Water Extractable B (WEB) Profile pH, EC, NO3, NH4, P, S, K, Ca, Mg, and Na
- Nutrient elements in the Basic and Complete Compost profiles are analysed as “totals” and reported on a dry weight basis.
- Nutrient elements in the Water Extractable profiles provide a “plant available” measure and are reported on a fresh weight basis.
Example Compost Report (Complete Compost and WEB Profiles)
Taking a Sample
Your composts have been processed from a mixture of biomass and/or other components and are not totally uniform in composition. We suggest that you collect several small ‘grab samples’ from your bulk compost and combine these to give a composite sample of approximately one kilogram and store it in a stout, sealed plastic bag or container.
Please provide additional information about the sample, particularly the constituents used and whether they may constitute a health hazard. This will ensure our staff can take appropriate precautions when handling these samples. Some particularly difficult samples may require additional sample handling and consequently incur additional costs.
How to Order a Test
Complimentary Soil & Plant Test Kits These sample kits contain instructions, an analysis request form, sampling bags and courier bag to send in the samples.
Guides and Supporting Information
Freephone 0508 HILL LAB (44 555 22) or email Ag.CSM@hill-labs.co.nz