Plant husbandry – Mulching
Reexamination Certificate
1999-11-24
2002-02-26
Jordan, Charles T. (Department: 3644)
Plant husbandry
Mulching
Reexamination Certificate
active
06349499
ABSTRACT:
TECHNOLOGICAL FIELD
The present invention pertains to artificial mulch for use in seedling establishments. More particularly, the present invention pertains to biodegradable artificial mulch which, when mixed with grass or other crop seeds, does not tend to segregate during shipping and handling.
BACKGROUND ART
Several types of artificial mulches are now commercially produced, each for a particular end use. For example, mulches for hydroseeding and like methods generally contain fluffy, hammered paper compressed into bales which must be time consumably added in small increments to the mulch tank. An improvement in such mulches is disclosed in copending U.S. patent application Ser. No. 08/970,065, which incorporates a surfactant into the mulch material. The surfactant produces more rapid wetting, allowing for much shorter addition times. In such mulches, the seed need not be kept separate from the mulch prior to addition to the mulch tank, as the mulch is generally supplied in a somewhat compacted bale form. If supplied loose, the seed would rapidly segregate during shipment of the mulch, resulting in portions of mulch with too high a seed content, and portions with too low a seed content.
Mulch and seed mixtures for crop establishment, particularly turf grass establishment, are available. Such products are spread in a dry state onto fields or, in particular, onto bare patches of soil. The mulch serves several purposes, primary of which are protecting of the seed from birds, protecting the seed from direct sunlight, and maintaining a moisture content which encourages germination. Seed mulches such as these are generally prepared from paper by hammer milling and like processes, producing a low density, fluffy product. Seed rapidly segregates from such mixtures. An improvement in seed-containing mulches is the preparation of mulch from paper and finely divided wood products, as disclosed in the inventor's own U.S. Pat. No. 5,916,027. The mulch thus prepared has a density close to that of seed, and thus seed is less likely to segregate during shipping and storage. However, the paper/wood product mulch of the U.S. Pat. No. 5,916,027 patent suffers from the disadvantage that wood products such as sawdust, and waste paper, are not always available.
SUMMARY OF THE INVENTION
The present invention provides for a preferably lignocellulosic mulch product which has a density adjusted to the density of the seed with which the mulch is to be used, and which is prepared from a variety of lignocellulosic starting materials. The invention also provides for unique mulch products, including mulch products having seed attached or incorporated within mulch flakes.
DESCRIPTION OF PREFERRED EMBODIMENT
The mulch flakes of the present invention may be prepared from any mix of lignocellulosic materials which allow the targeted density to be obtained. The targeted density is a density within ±50% of the average density of the seed to be mixed with the mulch, preferably within ±30%, more preferably within ±30%, and most preferably within ±10% of seed density.
The mulch may have any shape which is adapted to enable the mulch to perform its intended functions, for example assisting in maintaining the mulch and seed in location despite rain and watering; protecting the seed from the direct sun; and maintaining an adequate moisture level. Not all these functions must necessarily be met, and the mulch may serve other functions as well. It is preferable that the mulch be supplied in a flake form, i.e. in irregular platelets with a thickness which is less than the dimensions across the platelet. However, other shapes are useful as well, for example shapes resembling seeds, with aspect ratios of 1:1 to 1:10; preferably 1:1 to 1:5; long strips with aspect ratios greater than 10:1, and the like. It may be preferable to employ mixtures of several shapes in particular applications. While the density of the mulch flakes should approximate that of the seed, it would not detract from the invention to add less dense mulch products in small quantities, preferably less than 30% by weight, more preferably less than 15% by weight, and in particular less than 10% by weight. Low density diluents include those with a bulk density less than 4 lb/ft
3
, including products such as paper, shredded corn stalks, chopped wheat straw, and similar products.
The mulch flake material is preferably prepared from lignocellulosic materials. A wide variety of such materials are available, and include, without limitation, paper, sawdust, wood shavings, wood chips, excelsior, straw, seed husks, sterilized (denatured) seed products, coconut husks, copra, rice hulls, dried seaweed, yard waste, chipped bark, peat, compost, cotton, cotton linters, and the like. Alternative sources for mulch production include waste byproducts from industrial processing which are derived from natural sources, such as sewage sludge, which also generally and preferably contain some amount of lignocellulosic waste. An example is the raw material used to prepare Millorgorite™ fertilizer. These products may be used together with more traditional lignocellulosic feed stocks, or may be added to the product in admixture.
The particular selection of raw materials and their processing are dependent on the materials available and the target density. For example, a product of lower density may be made by including substantial unprocessed or partially processed materials such as paper, straw, chopped corn stalks, etc., into the mulch mix prior to agglomerating the mulch into its final form. To make a more dense mulch, the lignocellulosic materials may be more finely divided and/or more intensively processed prior to agglomeration and shaping. It is far more desirable to alter the density of mulch by incorporating less dense materials prior to shaping rather than to mix dry low density mulch with higher density mulch.
The processing of the mulch referred to above involves dividing the mulch raw materials to the desired size and shape, followed by optionally compounding, agglomerating, and shaping. These steps are not necessarily separate.
One form of processing involves digestion of the lignocellulosic products. In such a process, the lignocellulosic raw material is digested by means of superheated steam for an extended period. The heat and moisture causes breakdown of the lignocellulosic components to form a product which is easily extrudable or otherwise processable. If the heat is performed for a long enough period, for example, as disclosed in U.S. Pat. No. 5,017,319 and European Patents EP-A-O 161 766 and EP-A-O 492 016, all herein incorporated by reference, the raw materials will generate a natural “adhesive” binder which, following extrusion, will maintain the integrity of the extrudate prior to additional shaping operations such as chopping, shredding, flaking, etc. This intrinsic binder may be used in lieu of or in conjunction with other binders, permitting less use of the latter.
Alternatively, the lignocellulosic or other raw materials may be admixed with natural or synthetic binders, whether the raw materials are digested or undigested. Examples of synthetic binders include epoxy and novolac resins, phenol/formaldehyde condensates and like condensates employing in lieu of or in addition to phenol, melamine, urea, guanidine, biurea, and the like. Because the structural integrity of the mulch flake is not required to be of the same level as industrial products such as low, medium, and high density particle board, flake board, and the like, the amount of synthetic condensates necessary to provide the required integrity may be relatively low.
The amount of synthetic binder may be reduced further by addition of natural binders such as modified or unmodified starches, sugars, syrups, gums, and the like. Examples of natural and chemically modified natural binders include fructose, sucrose, molasses process residue, carboxymethylcellulose, hide glue, fish glue, shellac, mucilage, psyllium, gum tragacanth, gum acacia, guar gum, corn starch, ar
Brooks & Kushman P.C.
Jordan Charles T.
Palo Francis T.
Profile Products LLC
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