Fertilizer testing
We offer a wide range of fertilizer testing options as part of our services. These include: Mineral fertilizers, organic fertilizers such as farm manure (farmyard manure, slurry and slurry), digestate and compost as well as other residues from crop production and animal by-products.
With the accrued and/or purchased fertilizers, questions usually arise about quality (nutrient content, organic matter, ...) as well as quantity in terms of quantity or area fertilization. A particular challenge for farmers in this context is the requirement to use fertilizers in a sustainable and cost-efficient way. For this purpose, nutrient balances are useful, which reveal to farmers the interrelationships and perspectives in soil management (tillage, fertilization, crop rotation, etc.).
Fertilizer testing & Soil testing
The establishment of a balanced nutrient balance allows, among other things, the optimization of crop production (e.g. yield, quality, etc.) and the reduction of environmental problems (e.g. nitrate leaching, eutrophication, etc.). To meet these requirements, a soil investigation is useful. Subsequently, an investigation of the fertilizers used is also advisable in order to make efficient use of the farm's own resources.
The same applies to hobby horticulture, as knowledge about the nutrient supply can be used effectively by examining the own fertilizer (e.g. compost). Here, too, we recommend a prior soil examination or the performance of the soil check.
We offer a wide range of tests to check the quality of mineral and organic fertilizers, growing media, soil additives and plant aids, thus ensuring sustainable product quality.
Soil tests
The same applies to hobby horticulture, as knowledge about the nutrient supply can be used effectively via the examination of one's own fertilizer (e.g. compost). Here, too, we recommend a prior soil examination or the performance of the soil check.
We offer a wide range of tests to check the quality of mineral and organic fertilizers, growing media, soil additives and plant aids, thus ensuring sustainable product quality.
Sampling
During sampling by the client, care must be taken to ensure good mixing and homogeneity (e.g. sieving, mixing cross, etc.) of the sample for analysis.
We would like to point out that for each sampling adequate measures concerning occupational safety (gloves, respiratory protection, eye protection, ...) have to be taken. For samples (e.g. liquid and solid biogas slurry, compost, etc.) that are to be subjected to microbiological tests, hygiene standards must be observed in order to largely avoid secondary contamination by pathogens (salmonella, E. coli, etc.). The sampling equipment (sample scoop, scoop, etc.) used to take individual, bulk and final samples must be made of a material (e.g. stainless steel) that does not affect the qualitative nature of the sample. Immediate cooling (4 - 5 °C) of the sample is recommended so that stabilization of the sample properties at the time of sampling can be guaranteed.
Step 1: Sampling
Solid mineral, organic fertilizers and farm manure
For solid mineral and organic fertilizers as well as solid farm manure (farmyard manure, compost, solid biogas slurry, etc.), sampling must be carried out according to a representative sampling procedure. For this purpose, an adequate number (see Fertilizer Ordinance 2004 or Compost Ordinance 2001) of individual samples are to be taken from the available material with good mixing, which are combined to form a composite sample.
The composite sample is again mixed well with a sample shovel. A final sample of 0.5 - 3.0 kg is then taken from the composite sample. The sample quantity depends on the scope of the analysis, e.g. mineral fertilizer - analysis (NPK): approx. 0.5 kg; analysis of compost according to the Compost Ordinance BGBl. II No. 292/2001: approx. 3.0 liters.
Liquid mineral, organic fertilizers and farm fertilizers
To ensure good mixing and homogeneity of the sample at the time of sampling, liquid fertilizers are sampled after stirring or repeated pumping or when the stirrer is in operation (e.g. slurry pits, biogas slurry, etc.). For samples submitted to hygiene testing, sterilization of the sampling vessel (e.g. bucket) is required prior to sampling.
In the case of liquid biogas slurry, for example, the sample can be taken directly at the main valve of the biogas slurry tank or repository if it is easily accessible. To prevent microbiological contamination of the sample through the valve opening, the first 20 to 25 liters (approximately one bucket) should be discarded. After that, the sample is taken into the prepared (possibly sterilized) bucket from which the final samples can be taken.
Immediate cooling of the final samples reduces microbiological activity and guarantees stabilization of sample properties at the time of sampling. The sample volume is based on the scope of the analysis, with 0.5 - 1.0 liters of sample material usually being sufficient. Alternatively, sampling of the homogenized biogas slurry can be done with a scoop directly from the biogas slurry tank, if it is not possible to take the liquid biogas slurry through a valve opening.
We request you not to fill the sample vessels completely to the rim, otherwise the handling in the laboratory will be difficult.
Step 3 and 4: Order form and shipping
The sample must be accompanied by the fully completed order form (name, address, sample designation, date of sampling) with the desired analyses. The form can be found at the end of this page under Downloads (Order form for fertilizer analysis). We will be happy to assist you in filling out the order form. You can contact us for this by phone or by mail.
When sending the sample material by mail, please make sure that the sample is appropriately packed in a safe and stable manner and then send the package to:
Department of Soil Health and Plant Nutrition Spargelfeldstraße 191, 1220 Vienna.
Examination of main and trace nutrients as well as basic parameters
- Total nitrogen (Kjeldahl or elemental analysis)
- Nitrate nitrogen, ammonium nitrogen, organically bound nitrogen, carbamide nitrogen (urea)
- Total contents and/or water-soluble fractions of the elements phosphate, potassium, magnesium, calcium, sulfur and sodium
- Total contents and/or water-soluble fractions of trace nutrients (boron, copper, iron, zinc, manganese, molybdenum, cobalt)
- Nitrogen available (CaCl2), phosphate, potassium, and magnesium verf. in CAL or CAT, iron, manganese, sodium, copper zinc and boron in CAT extract (in growing media)
- Dry matter, organic matter, total carbon, C/N ratio
- Determination of electrical conductivity (salinity) and pH value
Further investigations
- Plant compatibility test for growing media, compost, fertilizers and soil additives: bio test with cress and/or Chinese cabbage
- Root growth test for soil additives, growing media and their raw materials as well as soil material (Petri dish test with cress)
- Test for germinable seeds and plant parts capable of sprouting ("weed test")
- Macroscopic and microscopic testing of fertilizers (and their starting materials)
- Epidemic hygienic testing: pathogenic E. coli, Salmonella sp., Listeria sp. , Campylobacter sp.
- quantification of E. coli and Enterobacteriaceae
- Determination or differentiation of Legionella
- Examination for Biuret
- Examination for aluminum
- Determination of anions by ion chromatography (sulfate, chloride)
- Determination of the filling quantity of growing media and soil improvers
- Determination of impurities (according to compost ordinance)
- Determination of sieve fractions
Recommended scope of analysis
The scope of analysis of your mineral or organic fertilizers recommended by us depends on the requirements of the respective fertilizer type according to the Fertilizer Act 1994 as amended in connection with the Fertilizer Ordinance 2004 as amended and can be taken from the links mentioned.
Kompost
- Total contents of nitrogen (N), phosphate (P2O5) and potassium (K2O)
- Organic matter (dry matter)
- Dry matter
- Copper (Cu)
- Zinc (Zn)
- Heavy metals according to fertilizer ordinance 2004 (lead, cadmium, chromium, nickel, mercury, vanadium, arsenic) in dry mass
For the marketing of compost as quality compost A or quality compost A+, an examination according to the Compost Ordinance BGBl. II No. 292/2001 is recommended.
Biogas slurry and digestate
Biogas slurry
Source material: from agricultural and forestry primary production as well as harvest and processing residues of agricultural products (according to Fertilizer Ordinance 2004)
- Total contents of nitrogen (N), phosphate (P2O5) and potassium (K2O)
- Organic matter (in the dry matter)
- Dry matter
Digestate
Source material: Residues from the treatment and processing of agricultural products and/or other biogenic residues from the food, luxury food and animal feed industries (Guideline "The proper use of biogas slurry and digestate in arable land and grassland" (BMLUK 2007))
- Total contents of nitrogen (N), phosphate (P2O5) and potassium (K2O)
- Organic matter (i.d.TS)
- Dry matter
- Heavy metals according to fertilizer ordinance 2004 (lead, cadmium, chromium, nickel, mercury, vanadium, arsenic) in dry matter
- Hygiene(E. coli, Salmonella, Listeria, Camylobacter)
Investigation of nitrogenous fertilizers for use in organic farming.
For the listing in the Easy-Cert operating resources catalog, the designation of the proportion of organic nitrogen is required. In this case, the following tests must be carried out:
- Total nitrogen content
- Content of inorganic nitrogen: nitrate, ammonium, urea.
The content of organic nitrogen is calculated as the difference between the total nitrogen and the mineral nitrogen.
Frequently asked questions about fertilizer testing
The following points should be observed:
- the sample must be well sealed
- the required quantity to be sent in (approx. 1kg or 1/2kg) should be taken into account, otherwise no proper examination can be guaranteed
- the sample containers must not be completely full
- no glass or metal containers
- enclose completed and signed order letter
- indicate the sender on the mail piece
The sample can be handed in on site or sent by mail to the following address:
AGES Ltd.
Department of Soil Health and Plant Nutrition
Asparagus Field Road 191
1220 Vienna
The competent authority in Austria for the control and supervision of the placing on the market of fertilizers, growing media, soil additives and plant aids within the meaning of the Fertilizer Act 2021 is the Federal Office for Food Safety (BAES). For all further information on the procedure, costs and process, please refer to the website of the Federal Office for Food Safety.
More Information & Services
Contact
Leitung
Dr. Andreas Baumgarten
- duengemittel@ages.at
- +43 50 555 34125
-
Spargelfeldstraße 191
1220 Wien
Last updated: 13.02.2026
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