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Recycling of feathers and down
Background:
It is estimated that in Germany alone the bedfeather processing industry generates apprx. 950 metric tons of waste feathers (quill and other feather waste) per year.
The quantity of waste feathers for the whole of Europe is of course much higher, to which can be added the future responsibility of the industry to dispose of used feahter/down bedding articles.
Our starting point was to investigate the possibilities of putting the organic feather waste to good use as a fertilizer in agriculture and horticulture.
Traditionally waste feathers generated by member firms are disposed of:
- to for instance gardeners or farmers
- to waste disposal sites
- to be incinerated
- to the feather meal industry.
But increasingly disposal to these sites have become difficult.
In order to avoid wasting resources, waste should be recycled and used for secondary purposes as a raw material.
A natural choice for using recycled feathers is as a fertilizer.
Three conditions have to be checked in order to use our waste feathers as a fertilizer in any way.
- What active substances in waste feathers have a positive effect?
- What are the harmful substances?
- Will the crops tolerate this kind of fertilizer and will it be effective?
First condition - active substances
| Comparison of the nutrient content in feather meal, horn meal, dung | |||
|---|---|---|---|
| feather meal | horn | dung | |
| (Mean values, examples) | |||
| organ. substances (C) (%) | 45 | 70 | 18 |
| nitrogen (%) | 14 | 10 | 1.7 |
| C/N ratio | 3.2 | 7 | 10.6 |
| Other main nutrients (g/kg TS ) | |||
| phosphorus | 2.9 | 1.8 | 2.5 |
| potassium | 1.5 | 1.2 | 5.0 |
| magnesium | 0.8 | 0.3 | 1.5 |
Fig. 1 Comparison of the nutrient content of feather meal, horn meal and dung
Second condition - harmful substances
| Heavy Metal Content of feather meal in comparison with green compost | |||
|---|---|---|---|
| feather meal | green compost | ||
| (Mean values; mg/kg TS) | |||
| lead | < 4 | 50 | |
| cadmium | < 0.4 | 0.4 | |
| chrome | < 4 | 25 | |
| copper | 15 | 30 | |
| nickel | < 4 | 10 | |
| mercury | < 0.02 | 0.2 | |
Fig. 2 Heavy metal content of feather meal in comparison with green compost
Third condition - Use and effectiveness of the fertilizer.
| Chemical Composition of the Nutrients in Feather Waste | |
|---|---|
| Situation: | Nutrients are bound in keratines (horn substances)
= high molecular protein which have a high chemical and mechanical resistance |
| The problem: | very low solubility and availability of the nutrients, e.g. for plant or animal nutrition
Immediately soluble nitrogen approx. 0.5% |
| Solution: | Nitrogen accessibility can be improved by grinding the waste feathers into feather meal (to promote the microbial conversion in the soil into soluble N compounds that can be digested by plants) |
| Project: | Study of the use of feather meal as organic nitrogen fertilizer in two research projects:
by:
|
The study was concentrated especially to areas where no synthetic mineral fertilizers are applied, i. e. to organic farming and horticulture.
Feather meal fertilizer could easily replace or enhance the use of milled horn and oil seed waste in farming and gardening.
Incubation tests were carried out in order to examine release of nitrogen in feather meal compared to milled horn.
Specimen of soil mixed with different concentrations of feather meal were prepared and kept for several weeks in a controlled atmosphere. At intervals the contents of mineralised (soluble) nitrogen (nitrate, ammonium) was determined.
The tests were carried out in Germany and China.
It was significant that test results in Germany showed a slightly higher percentage of mineralised nitrogen in milled horn than in feather meal.
Illustration 4: Release of nitrogen from feather meal and horn meal in a clay soil that is poor in nitrogen (Institute for Crop Nutrition at the University of Stuttgart-Hohenheim)
In China the case was exactly the other way round.
Illustration 5: Release of nitrogen (in %) from feather meal and horn meal in soil that is used for growing vegetables and in soil used for agricultural crops (incubation tests University of Peking)
A percentage of mineralised nitrogen of 50% after 12 weeks is a very good test result.
Further tests were carried out to establish the effectiveness of feather meal fertilizer compared to that of milled horn.
Illustration 6: Harvest yields (fresh weights) of (vegetable) rapeseed after fertilization with rough-ground feather meal and horn meal (1 mm) as well as with urea on agricultural soil (pot experiments by the University of Peking)
Feather meal of different qualities were used to fertilized various types of soil in order to establish crop yields and contents of nitrogen in vegetables.
Summary:
The tests have shown
- a comparatively quick and continuous release of nitrogen of feather meal.
- that the value of feather meal as a fertilizer is equal to that of milled horn.
The use of feather meal as an organic nitrogenous fertilizer in farming and gardening has good potential.
An approach to the German Ministry of Agriculture confirmed great interest in the use of secondary raw material fertilizers, such as feather meal fertilizer, and the Ministry would probably be prepaed to grant a permit for this purpose.