IE42392B1 - Process for manufacturing pressed peat substrates - Google Patents

Abstract

Shaped peat substrates contg. nutrients are produced by (a) stirring peat with an aq. soln. contg. lime-contg. materials, mineral fertilisers and trace elements until the moisture content of the peat is 93-97%; (b) pressing the peat substrate to the required shape; and (c) drying the product at 40-105 degrees C to a moisture content of >=15 vol. %. The substrates can be used as growing media for young plants. The substrates provide optimum growth conditions while being strong enough to protect the roots of the plants during transport and planting.

Description

The present invention relates to plant growing, and, more particularly, to processes for preparing artificial modia for growing agricultural, voody, decorative, floral, and other plants; more specifically, the present invention is directed to a prooess for manufacturing a pressed peat substrate.

The product of the process according to this invention can be widely employed for growing vegetable, floral, decorative, and woody seedlings in open or sheltered ground, as well as in making transferable decorative lawns.

It is known in the art to employ a variety of processes for preparing artificial peat media (or substrates) using highmoor (moss) peat layers decomposed to a minor degree .1 (not greater than 12 percent), which feature excellent water and air capacity and have a fibrous structure. In order to provide optimum conditions for the growth of cultivated plants- abundance of nutrient elements,, trace elements, water, air, and solid substances a nutrient substrate is prepared. To this end, extracted peat is comminuted and dried to a moisture content of from 12 to 20 percent, admixed with oalcitic material added at a rate of 6 to 8 kg/nZ, and stirred. Hequired inorganic macro-and microfertilizers are added to the mixture at a rate of from 0.1 to 2 percent by weight, whereupon the mixture Is again thoroughly agitated to achieve a uniform pattern of distribution of the nutrients through the bulk of calcified peat. The latter task involves great difficulties, though.

Owing to the low density (bulk weight) of tho upper peat layers with a low degree of decomposition, their utilization involves considerable transportation and storage - 2 42392 costs. For this reason, the peat substrate is pressed into briquettes, pellets, or cakes. Upon wetting, those substrate px'essings lose their shape and their initial volume is restored, i.e. they are reconverted to peaty ground which can be used for filling whatever containers are required, e.g. boxes, racks, or pots.

The plant seedlings grown in such a substrate are subsequ ently replanted in hothouses or open ground.

In the course of replanting, however, the root system 10 of the plant is damaged, with the result that the plant growth is stunted, the periods of flowering and fruiting are protracted, and. the crop yield is reduced.

To protect the root system, seedlings are grown in containers, such as peat pots, perforated and solid poly15 ethylene hoses, and bags filled with peat substrate or any othex’ nutrient media. It ia likewise known in the art to employ for the purpose pressed peat media, such as briquettes, pellets, and cakes, which are packaged in paper, kapron, polythene, and other netted or perforated envelopes, in order for them to preserve their shape upon wetting. However, manufacture and use of individual containers involve considerable financial outlays and manual labour, e.g. when replanting seedlings in reusable containers such as boxes or trays. Besides, the substrates placed in containers are liable to condense with time, losing their water-air properties optimum for the growing of seedlings.

There exists a technique for controlling the waterair ratio while manufacturing pressed peat substrates, whereby a peat substrate is added to elastic foamed poly20 urethane as a filler in the course of foaming, with the - 2 42302 mixture thus obtained, being subsequently hot-pressed.

This known technique also permits dispensing with the production of individual planting cells in favour of blocks of any desired size.' Such blocks effectively resist shape change and are quite sturdy, hence effectively protecting the root system of seedlings in transportation and replanting. The current trend in the manufacture of pressed peat substrates consists in improving the process for producing nutriculturc peat blocks through selecting more favourable compositions of the feedstock and introducing pore-forming agents, activators and foam stabilizers.

However, application of synthetic materials for the ? production of pressed peat media engenders new difficulties.' When planting seedlings in permanent ground, foamed polyurethane and other synthetic materials become significant sources of soil pollution, for they fail to dissolve or decompose in the·soil, raising a problem of collecting and removing synthetic residue.

What is desired is a process for manufacturing pressed peat substrates which would prove sturdy enough to protect the root system of plants in the course of transportation and replanting, and would also avoid the problem of soil pollution with synthetic materials upon replanning of the seedlings grown in such a substrate.

The present invention provides a process which comprises adding calcitic materials, inorganic fertilizers, and trace elements to peat, and pressing the substrate thus obtained, in which process the peaty mass is wetted with - 4 42392 stirring to a moisture content of from 95 to 97 percent with an aqueous solution containing calcitic materials, inorganic fertilizers and trace elements, whereupon the peat substrate thus obtained is subjected to pressing and then drying at a temperature of from 40 to 105°C to an average moisture content through the bulk of the end product of at least 15 percent.

The proposed process permits one to produce pressed peat substrates which are sufficiently sturdy to protect the root system of plants in the course of transport and replanting and avoids pollution of the soil with synthetic materials after replanting of seedlings grown on the substrate.

The pressed peat substrates can be produced in the form of blocks composed of individual planting cells having a geometrically regular and stable shape, making it possible to mechanize the processes of utilization of the pressed peat substrates. With the substrates prepared on the ba^is fr-i. f 1 of the organic matter of peat, not only are the plants provided with all basic nutrients, but the soil structure, biochemical properties, and phase ratio are improved, and photosynthetic processes are boosted due to the intensive liberation of carbon dioxide into the ground level air. Furthermore, since the heat-treated pressed substrates are entirely free of any pathogenic microorganisms, all operations to protect the plants against disease can be dispensed with.

Finally, the sowing and planting cells integrated in sturdy blocks require no containers to be set up and may - 5 42302 use any kind, of base, including concrete, planks, and ground: each individual cell, just as the entire block, constitutes a strong container enabling the root system to develop and protecting it against damage. Introduction of a prescribed quantity pf macro- and micronutrients in a liquid form conduces to a homogeneous consistency of the substrates as well as to a desired ratio of the solid, liquid and gaseous phases within each cell of the pressed substrate. The production of pressed substrates blocks instead of individual pots, cakes or briquettes is conducive to considerable savings in seedling transport storage, and replanting costs, with additional savings in the transport and storage costs in the period before the blocks are used [ for growing seedlings.

The composition and quantity of inorganic nutrients that go into the pressed substrates may be varied over a wide range without risk of deterioration of properties inherent in the prior art pressed peat substrates, so that they can be employed for growing a great variety of diverse cultivated plants, such as seedlings of vegetables: cucumbers tomatoes, cabbage, head and loose-leaved-lettuce, dill, and celery; seedlings of summer flowers: petunia, antirrhinum, aster, zinnia, sage, and begonia; pot-grown decorative plants and flowers: chrysanthemum. flame nettle, geranium, asparagus, and hydrangea; as well as plantlets of woody species, spruce, pine, larch, and cedar; pip- and stonefruit plantlets.1 apple-tree, pear tree, plum tree, and cherry tree; and plantlets of decorative and berry bushes, lilac, jasmine, water elder, spirea, currant, sea-buckthorn, and gooseberry. - 6 42382 To speed up the wetting of the pressed peat substrate, upon use, the initial peaty mass is preferably wetted with eh aqueous solution additionally containing surfaceactive agents in quantities of 0.1 to 0.2 percent by weight in terms of dry peat. Sulphates and sulphonates of fatty acids may be employed as the surface-active agents.

Further objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of the preferred process for manufacturing pressed peat substrates and exemplary embodiments thereof.

Owing to its colloid properties, peat is in itself a regulator of the optimum ratio of the solid, liquid, and gaseous phases in the peat substrates. The prior art pressed peat substrates, such as briquettes, pellets, and cakes, prepared from comminuted and dried peat, increase in volume upon wetting, restoring an optimum pore volume and thereby providing for the required set of air-water properties of the substrate. These air-water ratios are known from practical experience with peat substrates used for growing seedlings. Hence, if the volume of the peat substrate is to be maintained at a constant level, an optimum pore volume must be set in the course of pressing and must be maintained in the resultant block. It has been observed that the sods of peat retaining their original structure acquire strength upon drying. Thus, a rigid shape can be imparted to the substrate by drying the pressed substrate prepared from peat retaining its original fibrous - 7 43302 structure.

To this end, in accordance with the preferred process for the production of pressed peat substrates according to the invention, highmoor peat with a minor degree of decomposition (up to 15 percent), extracted and brought from a peatery without any processing, is separated from stumps. Then an automatically dispensed batch of peat is loaded into a vessel which is simultaneously charged with an aqueous solution containing calcitic materials, inorganic fertilisers, and micronutrients. The preferred calcitic materials are, e.g. ground chalk, slaked lime, quicklime, tufa, marl, dolomite flour, and shale ash.

The quantity of calcitic materials added to the peat mass is selected depending on their level of calcium as well as on the pli value specified for the product substrates.

The pH value of the product substrates is set with due regard for the reactivity of the plant environment; the amount of calcitic materials is determined accordingly.

Should said calcitic materials happen to contain, alongside calcium carbonate, magnesium (ground dolomite and dolomitized limestone: CaCO^ + MgCO^) and marl (dolomite flour), the latter two components are to be preferred since they give both calcium and magnesium to the peat substrate. If use is made of ground limestone, chalk, slaked lime, and tufa, magnesium sulphate is added to the peaty mass. The preferred inorganic fertilizers containing ammonia nitrogen, nitrate nitrogen, phosphorus, potassium, and.magnesium are ammophos, diaimilophos,potassium nitrate,ammonium nitrate,ammonium-sulphate - 8 42382 -superphosphate, potash salt, and magnesium sulphate. The rates at which inorganic fertilizers are added depend on their levels of active ingredient as well ae on the requirement that the N.P.K. ratio be maintained within specified limits.

Depending on the type of plant, the pressed peat substrates of this invention contain various amounts of inorganic additions with various N.P.E. ratios,-e.g. 1:1:1.5) 1:2:1; 1.5:1:1 1:1.5:2; etc.

The rate of NfK additions may be calculated by the formula; P = K.d/x.GT(100-uJ ), where P is the rate of each fertilizer, g d is the rate of active ingredient application, g x is the percentage of active ingredients G,j, is the weight of the peaty mass, kg K ia a coefficient for PgO^, ahd KgO.

The trace elements are preferably added to the substrate for each 100 g of absolutely dry peat as follows: MgO, 100 to 180 mg; MnO, 1 to 1.5 mg; B, 1.5 to 2 mg; Gu, 0.5 to 1.2 mg; Co, 0.00S mg; Mo, 1 to 1.2 mg; Pe, 0.6 to 1.00 mg; and Za, O.J to 0.4 mg.

The peaty mass is diluted with an aqueous solution containing c-alcitic materials, inorganic fertilizers, and microtrace elements to a moisture content of from 93 to 97 percent and then agitated by use of a mechanical paddle stirrer. This level of moisture is enough to break down - 9 42352 the peat-forming plants into components (stalks, leaves, and. roots) and proves ideal for producing a fluid mass which readily lends itself to pressing into substrate blocks.

Along with the breaking down of the peat-forming plants, the inorganic components are absorbed from the solution in the course of stirring.

In order to speed up the process of wetting of the pressed peat substrate before planting it to seeds, it is possible to activate its hydrophilic properties in the course of manufacture.

To this end, surface-active agents are additionally incorporated in the aqueous solution of calcitic materials, inorganic fertilizers, and trace elements during the preparation of the nutrient substrate. The surface-active agents are preferably anion-active preparations, such as sulphates and sulphonates of fatty acids, or sulphanol obtained by benzene alkylation with olefins followed by sulphonation and nutralization, as well as non-inorganic preparations, such as polyhydroxyethylene ethers of alkylphenols produced by condensation of organic substances containing active hydrogen (alkylphenols) with ethylene oxide.

The above-listed preparations display excellent wetting properties and are the least toxic of all known substances used in agriculture. Furthermore, these preparations all undergo biological decomposition, obviating the problem of soil pollution with toxic substances after replanting. ·- 10 42392 The surface-active agents are added to the aqueous solution of caloitio materials, inorganic fertilizers, and trace elements at the rate of from 0.1 to 0.2 percent by weight in terms of dry peat.

The surface-active agents introduced into the composition in· the foregoing quantities enable the product substrate to absorb moisture within prescribed limits, viz. from 400 to 800 percent.

The peaty mass thus prepared, which is known as a peat substrate, is now ready for being pressed. During pressing, the peat substrate is given a specified volume.

The mass is laid out as a layer of specified thickness and pressed on horizontal hydraulic presses into· a shaperetaining cohesive product with a specified porosity. This task is accompanied by dehydration of the peaty mass, e.g. from 97 down to 88 or 89 percent. Pressing ensures a specified shape and specified dimensions of the substrate. Usually, pressed media are manufactured in the form of blocks measuring 50 by 50 cm or 100 by 100 cm and having a thickness of 4 or 5 cmExcess moisture, together with, the substances dissolved therein and the small suspended particles it carries, is eliminated from the medium in the course of pressing. Therefore, this pressing water is preferably recycled.

The pressing water is passed through filters, where it is stripped of the suspended particles, and then sent to tanks as the feedstock fluid for preparing solutions and for other uses in the process. The additional capital outlay is more than made up for by the resultant reduction in water - 11 48302 and mineral consumption.

The pressed blocks are transported on a conveyor belt to air heaters, wherein hot steam or gas effects further dehydration of the peat substrate. The drying procedure is carried out at a temperature of from 40 to 105°C to an average moisture content through the bulk of the end product of at least 15 percent.

Peat drying causes irreversible changes in the colloid component thereof, affecting the hygroscopic properties of the peat and the products manufactured therefrom. The goal of manufacturing pressed media is to obtain highly porous and sufficiently hygroscopic products. Thus, the drying procedure should be so arranged as not to affect the hygroI scopic properties of the peat. This goal is achieved by drying pressed media at a temperature not higher than 105°G. The lower temperature limit, viz. 40°C, is accounted for by the fact that at temperatures below that limit the drying process slows down considerably without any gain in quality. By varying the temperature within these limits, the drying time may be controlled without any risk of losing hygroscopicity and the end products may be given whatever form is desired.

The final moisture content through the bulk of the end product should average at least 15 percent, since below this range the peat substrate becomes completely hydrophobic. If the pressed substrates are intended for prolonged storage, . their final moisture content should be higher in order to avoid overdrying. - 12 42392 Furrows are cut and holes for seeds are drilled in the pressed and dried blocks. The furrows 5 111111 wide and 25 to 50 nm deep are cut with face-and-side cutters or saws in the surface of the peat block in order to divide it (together with the seedlings grown in it) into individual cells measuring 50 by 5θ mm, 100 by 100 mm, etc. Such furrows may be formed in a raw slab as well, e.g. during pressing.

The holes formed in the centre of each cell to accommodate seeds, seedlings, or cuttings are preferably drilled so that the cells surface is rough and free of packed portions, providing optimum conditions for the germination of seeds of the growth of plantules or cuttings.

The end products are stacked and sent to the warehouse or shipped to the user. The pressed peat blocks require no special warehousing facilities. They may be kept under a film wrapping or a shed. The height of the stacks is not limited.

Thus the pressed peat substrates are sturdy enough to protect the root system of plants in the course of transportation and replanting, constitute no source of soil pollution, and also, being formed as blocks composed of individual planting cells with a geometrically regular and stable shape, enable the processes of growing and replanting seedlings to be easily mechanized. - 13 42393 Example 1 Excavated peat (upper peat of 10-percent decomposition, pH 2.77, end moisture content 92.9 percent) was freed from tree stumps and loaded into, a 10m^ tank equipped with a paddle 5 stirrer used for preparing peat nutrient substrate, the amount of peat being equivalent to 500 kg of dry peat. The peaty mass was diluted, with stirring, with an aqueous solution containing 50 kg of limestone flour and inorganic fertilizers: phosphate fertilizer containing 19 percent io p2o5, 15 kg; potash salt containing 40 percent KgO, 7-5 kg; ammonium sulphate containing 21 percent N, 15 kg.

Dilution was continued to a moisture content of 94*7 percent.

The peat substrate, homogenized by stirring, was fed to a hori15 zontal hydraulic press wherein moisture was pressed out to achieve a moisture content of 85*9 percent in the pressed medium. The pressed medium was a rectangular slab measuring 50 by 50 cm and having a thickness of 4 cm. The raw slab was laid on a shelf of a rack trolley. After all the shelves of the trolley 20 had been filled, the trolley was directed into an air heater, wherein the slabs were dried at a temperature of 105°0 to an average moisture content of 50 percent.

On a machine fitted with circular saws, furrows 5 cm deep and spaced at 5-cm intervals were cut in a square pattern !5 in the surface of dried pressed blocks, and holes for seeds were drilled in each square cell thus obtained.

The pressed substrate thus produced, having a pH value of 6.49, were used for growing seedlings of vegetables, viz* dill, onions, and lettuce. High-quality seedlings were obtained* - 14 42302 Example 2 Highmoor peat (7-percent decomposition, pH 3-0, and moisture content 92 percent) was freed from tree stumps, loaded .in an amount equivalent to 500 kg of dry peat into a 10m^ tank 5 for preparing peat substrate, and diluted with an aqueous solution containing 20 kg of chalk, 5-5 kg of potassium nitrate, .5 kg of superphosphate, 2.5 kg of ammonium nitrate, and 2 kg of magnesium sulphate. Trace elements were added to the solution in the following quantities; MgO, 500 g; MnO, 6 g; B, 8 g; Ou, 3 g; Mo, 5 g> Fe» g; and Zn, 1.5 g· Dilution was continued until the moisture content of the medium reached 97 percent, while simultaneously stirring the mixture with a paddle stirrer to achieve a homogeneous consistency. The substrate thus prepared was pressed on a horizontal hydraulic press to a moisture content of 88 percent.

The product was a rectangular slab measuring 50 by 50 cm and having a thickness of 4 cm. The raw slab was transported on a rack trolley to an air heater, wherein the slab was dried at a temperature of 100°0 to a moisture content of 29 percent.

The end product (pH 6.02) had an H:P:K ratio of 2.5ίΊί5; it was used for growing cucumber seedlings.

To this and, furrows 3 cm deep and spaced at 10 cm intervals were cut in the slab in a square pattern to form 25 square cells. A planting hole was drilled in each cell.

!S After replanting in a hothouse, the cucumber seedlings grown in the substrates showed 100-percent survival.

Use of 10 by 10 by 4 cm peat substrates allowed the growing of seedlings without dressing. - 15 42302 Example 7j Highmoor peat (7-percent decomposition, pH 5«0, 2nd moisture content 92 percent) was freed from tree stumps, loaded in an amount equivalent to 500 kg of dry peat into a 10m3 tank for preparing peat substrates, and diluted with an aqueous solution containing 20 kg of chalk, 5,5 kg of potassium nitrate, .5 kg of superphosphate, 2.5 kg of ammonium nitrate, and 2 kg of magnesium sulphate. Trace elements were added to the solution in the following amounts: MgO, 500 g; KnO, 6 g; B, 8 g; Cu, 5 g; Mo, 5 g; Fe, 4 g; and Zn, 1.5 g· Also added to the solution were surface-active agents, viz* polyhydroxyethylene ethers of alkylphenols, at the rate of 500 g. The solution was poured into the tank until the moisture content of the substrate reaches 97 percent, the mixture being simultaneously stirred with a paddle stirrer to achieve a homogeneous consistency. The prepared substrate was pressed on a horizontal hydraulic press to a moisture content of 88 percent. Pressing yielded a rectangular slab measuring 50 by 50 cm and having a thickness of 4 cm.. The raw pressed slab was transported on a rack trolley to an air heater, wherein the slab was dried at a temperature of 100°C to a moisture content of 29 percent.

The end product, which looked exactly like that of Example 2, had a pH of 6.02 and a N:P:K ratio of 2.5:1:5- The substrate, which became fully wetted within 50 minutes, was used for growing cucumber seedlings.

To this end, furrows 5 cm deep and spaced at 10 cm intervals were cut in the surface of the slab in a square pattern to form 25 cells. A planting hole was drilled in each - 16 42382 cell. The grown cucumber seedlings showed 100 percent survival upon replanting in hothouse soil.

Use of peat substrate measuring 10 by 10 x 4 cm permitted the growing of seedlings without dressing.

Example 4Highmoor peat (7-percent decomposition, pH J.O, and moisture content 92 percent) was freed from tree stumps, loaded in an amount equivalent to 500 kg of dry peat into a 10m^ tank for preparing peat substrates, and diluted with an aqueous solution containing 20 kg of chalk, 5·5 kg of potassium nitrate, J. 3 kg of superphosphate, 2.5 kg of ammonium nitrate, and 2 kg of magnesium sulphate. Trace elements were added to the solution in the following amounts: MgO, 500 g; MnO, 6 g; B, 8 g; Cu, 5 g; Mo, 5 g; Pe, 4- g; and Zn, 1.5 g. The solution was poured into the tank until the moisture content of the substrates reached 97 percent; simultaneously the mixture was agitated with a paddle stirrer to achieve a homogeneous consistency. The prepared substrates were pressed on a horizontal hydraulic press to a moisture content of 88 percent. Pressing yielded a rectangular slab measuring 50 by 50 cm and having a thickness of 4- cm. The raw pressed slab was transported on a rack trolley to an air heater, wherein the slab was dried at a temperature of 40°C to a moisture content of 40 percent.

The end product, with pH 6.02 and N:P:K ratio 2.5:1:?, was used for growing cucumber seedlings.

To this end, furrows 3 cm deep and spaced at 10 cm intervals were cut in the surface of the slab in a square - 17 42392 pattern to form 25 cells. A planting hole was drilled in each cell. The cucumber seedlings grown in such substrates showed 100 percent survival upon replanting in hothouse soil.

Peat substrates measuring 10 by 10 by 4 cm permitted the growing of seedlings without dressing.

Example 5 Highmoor peat (12-percent decomposition, pH 2.7, and moisture content 90 percent) was freed from tree stumps, loaded in an amount equivalent to 500 kg of dry peat into a 10m^ tank for preparing peat substrates, and diluted with an aqueous solution containing 25 kg of chalk, 5-5 kg of potassium nitrate, .5 kg of superphosphate, and 2.5 kg of ammonium nitrate, es well as trace elements added in the following amounts: Mgo, 600g; MnO, 5 g; B, 10 g; Cu, 5 g; Co, 30 mg; No, 6 g; Fe, 5 g; and Sn, g. The solution was poured into the tank until the moisture content of the substrate reached 95 percent; simultaneously, the mixture was agitated with a paddle stirrer to achieve a homogeneous consistency. The prepared substrate was pressed on a horizontal hydraulic press to a moisture content of 85 percent. Pressing yielded a rectangular slab measuring 50 by 50 cm and having a thickness of 4- cm. The raw pressed slab was transported on a rack trolley to an air hester, wherein tho slab was dried at a temperature of 40°C to a moisture content of 35·θ percent.

The end product (pH 5·05) was used for growing cabbage seedlings.

To this end, furrows 3 cm deep and spaced at 5 cm - 18 42302 intervals were cut in the surface of the slab in a square pattern to form 100 cells. A planting hole was drilled in each cell. The seedlings grown in such substrates showed 100 percent survival upon replanting in open ground. The peat substrates, containing specified amounts of micronutrient elements, enabled cabbage seedlings to be grown without dressing.

Example 6 Highmoor peat (12-percent decomposition, pH 2.7, and moisture content 90 percent) was freed from tree stumps, loaded in an amount equivalent to 500 mg of dry peat into a 10m^ tank for preparing peat substrates,and diluted with an aqueous solution containing 25 kg of chalk, 5·5 kg of potassium nitrate, 3.3 kg of superphosphate, and 2.5 kg of ammonium nitrate, as well as trace elements added in the following amounts: HgO, 600 g; MnO, 5 g; Β, 10 g; Ou, 5 g; Oo, 30 mg; Ho, 6 g; Pe, 5 g; and Zn, g. The solution was poured into the tank until the moisture content of the substrates reached 93 percent; simultaneously, the mixture was agitated with a paddle stirrer to achieve a homogeneous consistency. The prepared substrate was pressed on a horizontal hydraulic press to a moisture content of 85 percent. Pressing yielded a rectangular slab measuring 50 by 50 cm and having a thickness of 4 cm. The raw slab was transported on a rack trolley to en air heater, wherein the slab was dried at a tenqperature of 100°C to a moisture content of 20 percent.

The end product (pH 5-05) was used for growing cabbage seedlings.

To this end, furrows 3 cm deep and spaced at 5 cm intervals were cut in the surface of the slab in a square - 19 423S2 pattern to form 100 cells. Λ planting hole was drilled in each cell. The seedlings grown in the substrates showed 100 percent survival upon replanting in open ground. The peat substrates, containing specified amounts of trace elements, enabled cabbage seedlings to be grown without dressing.

Example 7 Highmoor peat (10-percent decomposition, pH 2.9, and moisture content 92 percent) was freed from tree stumps, loaded in an amount equivalent to 500 kg of dry peat into a 10m^ tank for preparing peat substrates, and diluted with an aqueous solution containing 20 kg of chalk and 9.4 kg of inorganic fertilizer containing 16 percent Ef, 16 percent PgO^, and 16 percent KpO. The solution was poured into the tank until the moisture content of the substrate reached 95 percent; simultaneously, the mixture was agitated with a paddle stirrer to achieve a homogeneous consistency. The prepared Substrate was pressed on a horizontal hydraulic press to a moisture content of 86 percent. Pressing yielded a rectangular slab measuring 100 by 100 cm and haying a thickness of 4 cm. The raw slab was transported on a rack trolley to an air heater, wherein the slab was dried at a temperature of 100°C to a moisture content of 15 percent.

The end product was used for making transferable decorative lawns.

To this end, furrows 0.8 cm deep and spaced at 5 cm intervals were cut in the surface of the slab in a square pattern. A planting hole was drilled in the centre of each - 20 42392 square cell thus obtained. The furrows and planting holes served as lines of alignment for the seeds of lawn grasses and at the same time as a system supplying water and air to the root system inside the slab. Vihen lawns are arranged indoors, the temperature of the substrates is to be maintained in the range from 18 to 22°C and the illumination in the range from 5,000' to 7,000 lux. ' - 21 -

Claims (5)

1. What we claim is:1. -A. process for manufacturing a pressed peat substrate, which comprises wetting feedstock peaty mass, with stirring, to a moisture content of from 93 to 97 5 percent with the aid of an aqueous solution of calcitic materials, inorganic fertilizers, and trace elements, to produce a peat substrate; subjecting the peat substrate, thus obtained to pressing; and drying the pressed, peat substrate at a temperature in the range from 40 to 105°C io for as long as is heeded to bring the average moisture content through the bulk of the pressed peat substrate to at least 15 percent.

2. A process as claimed in claim 1, in which the aqueous solution with which the feedstock peaty mass is 15 wetted additionally contains one or more surface-active agents to the extent of from 0.1 to 0.2 percent by weight in terms of dry peat.

3. A process as claimed in claim 2, in which the or each surface-active agent is a sulphate or sulphonate of 20 a fatty acid.

4. A process for manufacturing a pressed peat substrate, substantially as described in any of Examples 1 to 7.

5. A pressed peat substrate manufactured by a process 25 according to any preceding claim*