GB2394470A

GB2394470A - Method for producing a peatless culture substrate

Info

Publication number: GB2394470A
Application number: GB0404024A
Authority: GB
Inventors: Sandra Springer; Heinz-Dieter Molitor; Rainer Marutzky
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2001-08-25
Filing date: 2002-07-20
Publication date: 2004-04-28
Anticipated expiration: 2022-07-20
Also published as: GB2394470B; GB0404024D0; WO2003018511A1; DE10141792A1

Abstract

The invention relates to a method for producing a peatless culture substrate for cultivating plants and improving the soil. In order to produce a peat substitute, a mixture is produced from previously comminuted recycling chips of urea formaldehyde resin (U.F. resin)-bonded particles boards, from sawdust and/or sanding dust, as well as by adding nutrients, which are not contained or insufficiently contained in the compost product, for an optimal microbial decomposition. Said mixture is then submitted to an aerobic composting process, whereby said mixture is humidified to about 80 % of it maximal water-retaining capacity before the composting process and absorbed water is added, if necessary, during the composting process.

Description

GB 2394470 A continuation (74) Agent and/or Address for Service: Page

Hargrave Southgate, Whitefriars, Lewins Mead, BRISTOL, BS1 2NT, United Kingdom

- 1 Method for producing a Heatless culture substrate The invention relates to a process for the preparation of a peat-free culture substrate for plant cultivation and soil 5 improvement.

Since the extraction of peat is associated with the destruction and exploitation of biocycles which mold the landscape and since exploitable reserves are dwindling, 10 substitutes for peat have been increasingly used for many years, e.g. composted bark, coconut fibers and rice husks.

Waste paper and other cellulose materials have also already been used for the production of substrates.

15 It is an object of the invention to develop a peat substitute which can be produced economically, exhibits good physical properties and high stability of the nitrogen budget, and is also suitable for use as substrate component together with other substrate/mixing components, it being 20 possible for one of these substrate components in principle also to be peat.

This object is achieved according to the invention in that a mixture is prepared from recycling chips, comminuted 25 beforehand, of particle board bonded with urea-formaldebyde resin (UF resin) and from wood sawdust and/or wood grinding dust, with the addition, for optimum microbial transformation, of nutrients which are unavailable or not sufficiently available in the comporting product, and in 30 that this mixture is subjected to aerobic comporting, the mixture, before being comported, being dampened to approximately 80'6 of its maximum water capacity and water consumed during the comporting being replenished as required.

- 2 A process for the recovery of chips and fibers from derived timber product remnants bonded with urea-formaldehyde binders or with other hydrolyzable or chemically decomposable binders, old furniture, production scrap 5 materials, chippings and other materials comprising derived timber products is disclosed in DE 195 09 152 Al. In this process, in a first step, the derived timber product fragments are impregnated and soaked with a steeping or impregnating solution until they have absorbed at least 50'-', 10 of their dead weight of impregnating solution. In a second step, the impregnated derived timber product fragments are heated to 80 C-120 C. The derived timber product material, thus comminuted, can subsequently be graded by sieving and/or air classification.

The process according to the invention consequently exhibits the possibility of a material recovery for wood chips from the manufacture of particle board and from the recycling of furniture. By the use of such chips, which 20 exhibit a certain amount of nitrogen as a result of the binder which still partially adheres, the addition of nitrogen, usually necessary in conventional substrates based on wood, such as, e.g., with wood cuttings or wood fibers, can be dispensed with.

The peat-free substrates based on composted particle board chips with sawdust prepared according to the process according to the invention exhibit, in comparison to those based on white peat, advantages with regard to the physical 30 properties. Thus, the somewhat lower water storage capability contributes to an improved supply of oxygen to the roots. An improved rewettability and a high structural stability are also advantageous. No significant contraction in volume could be observed; wood chips proved to be 35 comparatively resistant to decomposition.

- 3 - The peat-free culture substrate prepared according to the invention moreover exhibits a price advantage with regard to current culture substrates. The costs for the starting 5 materials of the particle board/sawdust mixture, inclusive of lime and fertilizer, are only approximately half as great as the costs for white or black peat with nutrients and are considerably less than the costs for bark mulch.

10 In the process according to the invention, the statement

"80 , of its maximum water capacity" is to be understood as based on weight (80 g of water per 100 g of dry matter) and in practice allows a degree of latitude. In this connection, the amount of water per unit of weight or 15 volume required at the beginning of the comporting can be readily determined by ascertaining the actual moisture content and determining the maximum water capacity in the laboratory. Here, the addition of the required amount of water, together with a required amount of fertilizer 20 dissolved therein, is preferably carried out continuously in the preparation of the comporting product. In order to maintain the targeted moisture content, water consumed must repeatedly be replenished during the comporting as required, this then advantageously being carried out when 25 the comporting product is turned over.

Chemically/thermally/mechanically comminuted chips, sawdust from untreated softwood and grinding dust from the final treatment of particle board are preferably used according 30 to the invention.

An addition of calcium, e.g. of calcium in the form of calcium carbonate, in an amount of up to 8 g/l of substrate, preferably approximately 2 g per liter of 35 substrate, is particularly advantageous, the amount of the

- 4 calcium addition depending on the pH buffering of the starting material.

Insofar as nutrients are not available or are not 5 sufficiently available in the composting product, nutrients necessary for an optimal microbial transformation must be added. This can be carried out both using individual salts and using a nitrogen-free compound fertilizer and in fact in an amount of 0.4-1.5 g, preferably approximately 0.5 g, 10 of base fertilizer per liter of substrate.

In addition, it is advisable to add 2 10't bark mulch, bark humus, compost and/or shredded waste paper to the mixture to bind the formaldehyde and ammonia released in the 15 starting phase of the comporting.

The invention is based on the principle of combining a source which supplies inorganic nitrogen with a source which consumes nitrogen. Thus it can be advantageous to add 20 equal parts of recycling chips and of sawdust to the mixture. A mixture of 50% comminuted recycling chips of particle board bonded using UF resin and 50'', sawdust from untreated softwood has proved to be particularly promising.

The addition of a base fertilizer (0.5 g per liter of 25 substrate) and the addition calcium in the form of CaCO (2 g per liter of substrate) are important in this connection. It is recommended to compost for approximately 12 weeks in 30 order to bring the nitrogen turnover to a conclusion.

Subsequently, the material can be used as it is or in very high proportions as substrate. The duration of comporting depends on the comporting conditions with regard to temperature, aeration and humidity.

In a trial in which Euphorbia pulcherrima was grown in a customary way, clear differences in growth appeared after a growing time of just 8 weeks. At that time, the growth achieved in the mixtures derived from particle board chips 5 and sawdust was comparable with that achieved in the standard soil. In contrast thereto, the growth was poorer in the alternative forms with bark or paper. The differences ascertained in the intermediate evaluation were to a large extent maintained up to the end of growth. The 10 improved root growth and the healthy white roots in the alternative forms with particle board chips were striking in comparison with the standard soil. This might be put down essentially to the higher pore volume and thereby to the improved oxygen supply of these alternative forms.

Claims

- 6 - WHAT IS CLAIMED IS:

1. A process for the preparation of a peat-free culture 5 substrate for plant cultivation and soil improvement, characterized in that a mixture is prepared from recycling chips, comminuted beforehand, of particle board bonded with urea-formaldehyde resin (UF resin) and from wood sawdust and/or wood grinding dust, with 10 the addition, for optimum microbial transformation, of nutrients which are unavailable or not sufficiently available in the composting product, and in that this mixture is subjected to aerobic comporting, the mixture, before being comported, being dampened to 15 approximately 80 r; of its maximum water capacity and water consumed during the comporting being replenished as required.

2. The process as claimed in claim 1, characterized by 20 the use of chemically/thermally/mechanically comminuted chips.

3. The process as claimed in claim 1 or 2, characterized by the use of sawdust from untreated softwood.

4. The process as claimed in claim 1, 2 or 3, characterized by the use of grinding dust from the final treatment of particle board.

30

5. The process as claimed in one of the preceding claims, characterized by an addition of calcium.

6. The process as claimed in claim 5, characterized by an addition of calcium in the form of calcium carbonate 35 of up to 8 g/1 of substrate, preferably approximately 2 g/1 of substrate.

!

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7 7. The process as claimed in one of the preceding claims, characterized in that the nutrients are individual salts or a nitrogenfree compound fertilizer.

8. The process as claimed in claim 7, characterized by an addition of 0.41.5 g, preferably of approximately 0.5 g, of base fertilizer per liter of substrate.

10

9. The process as claimed in one of the preceding claims, characterized in that 2 109, bark mulch, bark humus, compost and/or shredded waste paper are added to the mixture to bind the formaldehyde and ammonia released in the starting phase of the comporting.