As known, mulching is a gardening technique which consists in covering soil, in general in flowerbeds or at the base of shrubs, with plant and/or inorganic material. Mulching has many aims. For example, mulching is effected to control weeds in a flowerbed or at the base of trees; to avoid thermal shock and in particular to protect shoots or bulbs from freezing; to maintain a constant humidity level; to improve soil texture and to fertilise, in the case that organic/plant mulches are used.

In addition to these direct advantages mulching also offers less obvious benefits, such as: long-term reduction of weeds in flowerbeds contributes to weed control in surrounding areas used as lawn; the protection of roots from thermal shock permits improved root development and therefore greater plant wellbeing; constant humidity permits water saving and reduced plant stress; constant humidity prevents infestation by organisms such as the so-called red spider mite and other mites.

There are substantially two types of mulching, organic and inorganic. Inorganic mulching generally consists of gravel, volcanic lapilli, clay, shells and similar. Organic mulching, in contrast, usually consists of leaves, bark, compost, shredded twigs, wood chip, rotted manure, peat, and similar.

Both types of mulching offer advantages and disadvantages. Inorganic mulching is generally longer lasting, but does not improve soil structure and has no fertilising power. Furthermore, its herbicidal effect is weak and a base sheet must usually be laid down to impede weed growth. In contrast, organic mulch optimises soil texture, fertilises it, and gives better thermal insulation, but must be re-supplied with new material every year and can encourage rot, especially if too damp.

Among organic mulches, one of the best known and used is bark, normally pine bark, which does however have some inconveniences. First, to be effective it must be deposited to a considerable thickness, and must in any case be renewed every year. Furthermore, it is not completely effective in preventing weeds, and nursery workers may have to spray the treated surface with chemical weed killers as often as two or three times a year. It must be subjected to continuous maintenance as, being easily removable, the effective thickness may be altered, for example by animals or environmental factors such as water or wind, and for the same reason it can not be walked on. It has also been found that bark can favour the onset of fungal diseases. Finally, it is known that bark, and other organic mulches such as pine needles and the leaves of certain plants such as chestnut and beech, tend to acidify the soil, for which reason they can not be used on chalcophil, basophil, or in any case non-acidophil.

The primary task of the present invention is that of realising a mulching composition which permits the above described inconveniences to be avoided, and, in particular, which has good mechanical stability and is not displaced by water, wind or animals.

Within this task, one of the scopes of the present invention is that of realising a mulching composition which is endowed with characteristics such as to guarantee both an efficient herbicidal effect and the contribution of micro-elements to the soil.

Another scope of the present invention is that of realising a mulching composition which has a multi-year duration.

Another scope of the present invention is that of realising a mulching composition which impedes the onset of fungal diseases.

Another scope of the present invention is that of realising a mulching composition which can be used with all types of plant, independent of whether they are acidophil or not.

Another scope of the present invention is that of realising a mulching composition which can be integrated with the soil in the case of the site's reorganisation.

Not least, the scope of the present invention is that of realising a mulching composition which is highly reliable, relatively easy to realise and has a competitive cost.

This task and these scopes, as well as others which shall better appear below, are achieved by a mulching composition, according to the invention, characterised by the fact that it comprises from 50 to 90 parts of at least one porous inorganic material and from 5 to 40 parts of at least one binding compound.

In this way, thanks to the innovative nature of its constituents, the composition according to the invention allows achievement of a soil surface treated in such a way as to impede weed growth, permitting at the same time good nutrition and hydration of the soil itself. The compact and microporous structure in fact impedes rooting of seeds in the underlayer, without limiting the transport of water to the culture medium below.

Further characteristics and advantages shall become more evident from the description of embodiments, preferred but not exclusive, of an inorganic mulching composition, according to the invention, described below as an indicative and non-limiting example.

As said, the mulching composition according to the invention comprises from 50 to 90 parts of at least one porous inorganic material and from 5 to 40 parts of at least one binding compound. Preferably, the composition according to the invention comprises from 10 to 35, more preferably from 20 to 30 parts, of said binding compound.

The porous inorganic material has general characteristics such as to guarantee good air flow and drainage. Among porous inorganic materials, one of the preferred is expanded clay which, preferably, should not contain organic substances and should not decompose; furthermore, it should not be attackable by moulds or parasites. An example of expanded clay utilisable in the mulching composition according to the invention is the product marketed in various sizes with the name AgriLeca.

Other porous inorganic materials can be used in alternative or in combination with expanded clay, such as pumice and volcanic lapilli.

The binding compounds can be both inorganic and organic, and the latter can be both natural and synthetic. Preferably, the binding compound must be able to react with water in order to carry out its effect. Examples of inorganic binding compounds are hydraulic binders such as gypsum and cement, while among organic binding compounds various types of water-reactive glues and resins can be cited as examples.

Among the binding compounds utilisable in the mulching composition according to the invention, use of a hydraulic binder, for example cement dust, is preferable. The preparation of the composition according to the invention is performed very simply by mixing the porous material with the binding compound in the proportions described above.

Preferably, the composition according to the invention further comprises from 0.1 to 200 parts of one or more additives, preferably chosen among mineral additives, and/or organic or inorganic fertilizers and/or non-toxic dyes.

The additives have the aim of improving the composition's mineral load and/or improving the fertilizing capabilities of the composition; in this way water crossing through the mulching composition layer is enriched with the micro-elements it contains, supplying them to the root system of the plant it is desired to improve.

Preferably, additives are chosen from among sand, coal dust, marble dust, quartz dust and their mixtures. In this case, the composition according to the invention can comprise from 0.1 to 50 parts of one or more additives, preferably from 0.2 to 10 and, more preferably, from 0.5 to 5 parts of said one or more additives. Obviously other mineral additives, alone or in combination with each other and/or the additives cited above, may also be utilised.

Alternatively, or in addition to the above mentioned additives, the composition of the invention can comprise also one or more organic or inorganic fertilizers. In such a case, the composition according to the invention can comprise from 0.1 to 200 parts of one or more additives, preferably from 0.2 to 100 and, more preferably, from 0.5 to 50 parts of said one or more organic or inorganic fertilizers. Obviously the organic or inorganic fertilizers can be used alone or in combination with the additives cited above.

Furthermore, additives may also be constituted of one or more non-toxic dyes, both alone and in combination with the above cited mineral additives. In this way it is possible to also considerably improve the aesthetic aspect of the portion of surface treated with the mulching composition according to the invention, imparting it with the colouration which best fits in with the characteristics of the surrounding environment. For example, by using a red dye it is possible to give the treated surface the warm coloration typical of recently worked soil, while a green dye will simulate the appearance of a lawn. Naturally, other combinations and variations are possible, without moving away from the spirit of the present invention.

A typical example of a preferred mulching composition comprises from 50 to 90 parts of said porous inorganic material and from 10 to 35 parts, preferably from 20 to 30 parts, of said binding compound, from 0.2 to 10 parts of an additive chosen from sand, coal dust, marble dust, quartz dust, and their mixtures, from 0.1 to 100 parts of an organic or inorganic fertilizer and from 0.2 to 5 parts of said non-toxic dye.

A typical elemental analysis of a preferred mulching composition gave the following results: soluble iron 0.02 mg/1 soluble manganese 0.01 mg/1 soluble zinc <0.01 mg/1 soluble copper <0. 01 mg/1 soluble aluminium <0. 01 mg/1 calcium 567 mg/1 magnesium <0. 01 mg/1 The present invention in a further of its aspects also regards a mulching method characterised by the fact that it comprises the following phases: spread on the soil a layer of mulching composition according to the previous description; treat the mulching composition with water Treatment of a soil surface with the mulching composition according to the invention may in fact be effected very simply according to the following method. On the previously worked soil, professionally levelled and free from foreign materials, a uniform layer of a few centimetres of the previously described dry mulching composition is spread. It is then sprayed with rain, or better, with water, ensuring the material is completely soaked. On the basis of the various requirements it is useful to repeat the soaking operation after a few hours, in order to ensure a better texture of the mulching material layer in use.

Alternatively, especially in urban areas or on steep slopes, it is also possible to form a mixture of a previously described mulching composition with water and then spread the mixture on the surface to be treated.

A further alternative method involves the formation of a mixture of a previously described mulching composition with water; the mixture is subsequently put into moulds of the desired size and shape so as to obtain briquettes which may be subsequently placed according to necessity.

It is in fact seen that one of the characteristics of the mulching composition according to the invention is its ability to stabilise downward sloping land, making mulching possible even in difficult places.

Furthermore, given its characteristics of compactness once in operation, the mulching composition according to the invention can also be walked on without compromising its characteristics: If it is planned that the area should be walked on, it is however preferable to prepare the underlying ground so that it is sufficiently solid and compact.

It is clear from what has been described that the mulching composition according to the invention achieves all the pre-fixed scopes and objectives, presenting notable advantages over known art in terms of both performance and production costs.

It is in fact seen that, in contrast to mulches of known type, both organic and inorganic, the composition according to the invention present an excellent set of characteristics.

In particular, it is seen that the mulching composition according to the invention; - impedes the onset of fungal diseases; - is suitable even for non-acid-loving plants; - is not removed or displaced by water, wind or animals ; - stabilises soil on downward slopes; - facilitates cleaning, including with mechanical equipment, thanks to its compact surface; - is completely respectful of the environment; - can be integrated with the soil in the case of the site's reorganisation; -carries microelements to the underlayer; - inhibits insect establishment and proliferation; - avoids use of weed killers ; - has a pleasing and tidy appearance; - can be walked on; - does not require maintenance.

Furthermore, the mulching composition according to the invention may be installed very simply without the use of special equipment.

The composition thus conceived is susceptible to numerous modifications and variants, all entering within the scope of the inventive concept; furthermore, all details may be substituted by other technically equivalent elements.