Description The present invention relates to compacted, compressed or pressed plant growth substrates and to methods for obtaining the present compacted plant growth substrates.

Presently, compacted, compressed or pressed plant growth substrates blocks capable of providing a growth substrate for one or more plants are made of pressed blocks of peat and especially black peat.

Peat, or turf, is an accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands or mires. Peatlands, also known as mires are the most important source of peat. Peat can be harvested as a source of fuel or can be used in agriculture and horticulture as a plant growth substrate especially in the form pressed blocks being the standard growth substrate for a range of vegetable seedling.

Peat, although organic in origin, is not generally regarded as a renewable source as its extraction rate in industrialized countries far exceeds its slow regrowth rate of generally 1 mm per year. Accordingly, there is a need in the art of agriculture and horticulture to provide an alternative for pressed peat blocks. Present alternatives for pressed peat blocks, such as Rockwool blocks cannot be used in, for example, the organic certified vegetable production systems or do not provide adequate growth characteristics, especially for seedlings or young plants and/or plant cuttings.

Considering the above need in the art it is an object, amongst other object, of the present invention to provide an alternative for pressed peat blocks. A requirement of such alternative is that, after compression, the pressed blocks will holds form and do not crumble.

The above object, amongst other objects, is met by the present invention as outlined in the appended claims.

Specifically, the above object, amongst other objects, is, according to a first aspect of the present invention, met by a method for providing a compacted plant growth substrate comprising:

a) providing vermicast;

b) mixing said vermicast with a carrier, preferably in a ratio of vermicast to carrier of 70% to 30% (wt.) vermicast -to 30% to 70% (wt.) carrier, for providing a plant growth substrate;

c) compressing said plant growth substrate into blocks with a water content of 50% to 80% (wt.) capable of providing a growth substrate for one or more plants, preferably seedlings and/ or young plants and/or plant

cuttings.

Vermicompost is organic waste composted by worms, such as red wigglers, white worms, or other earthworms and is composed of a heterogeneous mixture of decomposed organic waste, such as vegetable or food waste, bedding materials, and vermicast. Vermicast, also designated as worm castings, worm humus or worm manure, is the excretion of a worm when predating on organic waste. These excretions have been shown to contain high levels of nutrients some of which are water-soluble. Containing water-soluble nutrients, vermicompost is generally regarded as an excellent, nutrient-rich organic fertilizer and soil conditioner. The process of producing vermicompost is also designated as vermicomposting.

Vermicompost has been shown to be richer in many nutrients than compost produced by other composting methods. Vermicompost is rich in microbial life capable of converting nutrients present in soil. Unlike other compost, vermicompost comprises worm mucus helping to prevent nutrients from washing away with the first watering and, additionally, retains moisture better than plain soil. Benefits of vermicompost are, amongst others, improved soil aeration, enriched soil with micro-organisms, improved water holding capacity, enhanced germination, plant growth, and crop yield and improved root growth and structure.

An earthworm species which can be used for vermicompositing is Eisenia fetida or Eisenia andrei. Eisenia hortensis, Eudrilus eugeniae, Lumbricus rubellus, and Perionyx excavatus are other suitable examples of worm species which can be used to provide vermicast.

Two main methods of large-scale vermiculture are known. The first method uses large bins, sacks or any other organic waste container comprising bedding materials and organic waste. The second method of large-scale vermicomposting system is a raised bed or flow-through system. In this system, the worms are fed a layer of "worm chow" across the top of the bed, and an layer of castings is harvested from below by pulling a breaker bar across the large mesh screen which forms the base of the bed.

The most common worms used in composting systems, redworms {Eisenia fetida, Eisenia andrei and Lumbricus rubellus) feed most rapidly at temperatures of 15-25 °C. Other worms like Perionyx excavatus are suitable for warmer climates.

There are few organic wastes that vermicomposting cannot compost, although meat waste and dairy products are likely to putrefy instead of composting and, when present in outdoor bins, can attract vermin. Green waste can be added to facilitate composting of meat waste and dairy products. Suitable organics waste for vermicomposting includes fruits and vegetables, vegetable and fruit peels and ends, dairy cow or pig manure, sewage sludge, agricultural waste, food processing and grocery waste or grass clippings and wood chips although other organic waste source can be contemplated. Within the context of the present invention, it is essential that the present pressed or compressed plant growth substrate blocks have a water content of 50% to 80% (wt.) to allow the blocks hold form and to prevent crumbling.

According to a preferred embodiment of this first aspect of the present invention, the present carrier is selected from the group consisting of coco coir, bark, peat, husk and combination thereof and according a more preferred embodiment, the present carrier is coco coir. Coir is a natural fiber extracted from the husk of coconut and used in products such as floor mats, doormats, brushes, mattresses, etc. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut.

According to another preferred embodiment of this first aspect of the present invention, the present step of providing vermicast comprises:

growing earthworms in a substrate comprising organic waste during a period a period of 3 to 10 weeks thereby providing composted organic waste;

- mixing said composted organic waste with water to provide a slurry; separating from said slurry worms, cocoons and juveniles partially composted solid organic waste and organic waste thereby providing a sludge;

drying said sludge thereby providing vermicast.

Earths worms are generally put into a container and organic waste material is added on top optionally mixed with carrier or filler materials. The organic waste material can be a wide variety of products such as kitchen waste; garden cuttings; wood production side products such as bark stripping; animal feaces or slurry of biogas plants. The container can be of any given size or material, as long as it holds the waste material and worms. After about 3 to 10 weeks such as 6 to 8 week the vermicast is formed, i.e. the organic waste is composted by the worms.

Subsequently, the content of the container can be transferred into a tank containing water and an agitator. In this tank, the vermicast is processed into a suspension or slurry. This step generally requires about one hour of agitation. Then, as an example of separation, the tank is emptied onto a sieve, where the solids, mature worms, worm cocoons, and juveniles and the non- composted, or partially composted, organic waste are separated. Subsequently, the sludge obtained can be pumped up in to separation tanks and the worms (cocoons juveniles and mature) can be recycled for further vermicomposting or sold separately for other purposes.

In the separating tanks the suspension is generally left overnight allowing the semi-solid material to settle, or sediment at the bottom of the tank. The water is then pumped out and this water, also designated as compost thee, can be used for irrigation purposes. The semi-solid can dried and either stored or directly used to fabricate all sizes of blocks. The drying can be done naturally or forced, but not at high temperatures, i.e. generally above 40°C, in order to preserve the beneficial microorganisms from in the vermicompost.

The vermicast is mixed with a carrier such as coco coir, a byproduct of the coco matting industry and is made from the husk of the coco nut. The pressing, compacting or compression to produce the present blocks is generally performed using a machine used for producing peat blocks.

Considering the above, yet another preferred embodiment of this first aspect of the present invention comprises:

sieving said slurry thereby separating from said slurry said worms, cocoons juveniles and mature and partially composted solid organic waste and solid waste.

Considering the above, still another preferred embodiment of this first aspect of the present invention comprises sedimentation of said sludge and drying the sediment obtained.

Although the present method provides an excellent growth substrate, it is contemplated within the context of the present invention that during or after step (b) but before step (c) plant nutrients and/or plant growth promoting agents are added such as macro elements, spore elements or hormones.

According to a second and third aspect, the present invention relates to compacted plant growth substrate blocks obtainable by the method as outlined above or compacted plant growth substrate blocks capable of providing a growth substrate for one or more plants, preferably seedling and/or young plants and/or plant cuttings, comprised of vermicast and a carrier, preferably in a ratio of vermicast to carrier of 70% to 30% (wt.) vermicast to 30% to 70% (wt.) carrier, and having a water content of 50% to 80% (wt.).

The present compacted plant growth substrate blocks preferably comprise a carrier selected from the group consisting of coconut waste, coco coir, bark, peat, husk, saw dust, wood chips and combinations thereof although other organic matter is contemplated within the context of the present invention.

According to a fourth aspect, the present inventions relates to the use of vermicast for providing compacted plant growth substrate blocks capable of providing a growth substrate for one or more plants, preferably seedlings and/or young plants and/or plant cuttings.

An illustrative example of the present compacted plant growth substrate blocks capable of providing a growth substrate for one or more plants, preferably seedlings and/or young plants and/or plant cuttings is provided in Figure 1. An illustrative example of a machine for compressing the present plant growth substrate into blocks is provided in Figure 2.