Process for soil conditioning by aerial application of water soluble or swellable polymers

Abstract

Process for soil conditioning includes applying to the soil a composition comprising at least a water soluble or swellable polymer. The composition has a particulate form and is applied by an aerial application. The process is suitable for soil conditioning and for reduction in soil erosion in agriculture, forestry, construction and civil engineering, mining, water storage and transportation, protection of rivers and delta against pollution, environmental conservation.

Claims

1. A process for conditioning of soil to control erosion by water or wind path, control formation of slacking crusts, and preserve soil aggregate structure, comprising: applying to the soil a composition, said composition comprising at least one of a water soluble or a water swellable polymer, the at least one polymer being obtained by polymerization of acrylamide and monomers with an ethylenically unsaturated moiety selected from the families consisting of: anionic monomers selected from the group consisting of monomers with an acid carboxylic moiety and monomers with a sulfonic acid moiety, and non-ionic monomers selected from the group consisting of: methacrylamide, N-alkylacrylamide, N,N-dimethylacrylamide, methylolacrylamide, vinylformamide, N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkyl(meth)acrylates and (meth)acrylates with an alkoxy chain, wherein molecular weight of the water soluble polymer is above 500,000 g.Math.mol.sup.1, and wherein the composition is in particulate form, and wherein said applying comprises performing an aerial application of the composition by airplane, helicopter, hang glider, sailplane or drone.

2. The process according to claim 1, wherein the water soluble polymer has a molecular weight between 500,000 and 30 million g.Math.mol.sup.1.

3. The process according to claim 1, wherein the at least one of the water soluble polymer and the water swellable polymer in the composition is in powder or bead form.

4. The process according to claim 1, wherein particle size of the particulates of the composition is between 0.5 and 4 millimeters.

5. The process according to claim 1, wherein the composition comprises between 50% and 100% by weight of the at least one of the water soluble polymer and the water swellable polymer.

6. The process according to claim 1, wherein the composition has a bulk density between 300 and 1000 kg.Math.m.sup.3.

7. The process according to claim 1, comprising performing at least one additional aerial application.

8. The process according to claim 7, wherein the additional aerial application is performed at least 20 days and not more than 40 days after a previous aerial application.

9. The process according to claim 1, wherein amount of the composition which is applied to the soil is comprised between 0.1 and 500 kg/ha.

10. The process according to claim 1, comprising performing soil conditioning in agriculture, forestry, construction and civil engineering, mining, environmental conservation, protection of rivers and delta against pollution, water storage or transportation.

11. The process according to claim 10, comprising performing soil conditioning in agriculture, and performing the aerial application in crop fields between planting and a subsequent first rain event or irrigation.

12. The process according to claim 1, wherein the aerial application is performed at an altitude below 50 m.

Description

DESCRIPTION OF THE INVENTION

(1) The present invention intends to solve the problem previously described.

(2) The object of the invention is a process for soil conditioning consisting of applying by an aerial application to the soil, a composition in particulate form, said composition comprising at least a water soluble or swellable polymer.

(3) In the following of the description, particulate form means powder, bead, tablet, prill or a mixture thereof having a size preferably between 0.1 and 10 millimeters, advantageously between 0.5 and 4 millimeters.

(4) Polymer Description

(5) The composition applied in the process of the invention comprises at least a water soluble or swellable polymer.

(6) A water soluble polymer is a polymer which gives a solution without insoluble particles when it is dissolved under agitation at 25 C. and with a 50 g/L concentration in water.

(7) A water swellable polymer is a polymer which swells and thickens solution when it is put in water at 25 C.

(8) Water soluble or swellable polymers are selected from the group comprising: Homopolymers and copolymers of acrylamide, acrylic acid and its salts, methacrylic acid and its salts, acrylonitrile, 2-acrylamido-2-methyl propane sulfonic acid and its salts, vinylpyrolidone, vinylformamide, vinyl acetate, maleic acid or ethylene oxide and derivatives likes hydrolysed polyacrylonitrile, polyvinyl alcohol; Natural polymers, natural gums, polysaccharides and their derivatives: galactomannan, guar gum, carob gum, xanthan gum, arabic gum, chitosan, carrageenan, pectins, starch, modified starches, alginates, celluloses, cellulose derivatives (cellulose ethers), agar-agar; Starch-acrylamide-acrylates, starch-acrylonitrile, chitosan-acrylic acid copolymers.

(9) For the process of the invention, polymers or copolymers of acrylamide are the most interesting.

(10) Polymers of the invention can be linear, structured or cross-linked. The term structured polymers signifies polymers in branched, star or comb form.

(11) Branched polymers are classically not linear polymers with lateral chains. Cross-linked polymers are classically not linear polymers under a tri-dimensional array form, insoluble in water, but which swell in water.

(12) Polymers of the invention are preferably anionic. Their anionic charge content is preferably between 5 and 60 mol %.

(13) Water soluble or swellable polymers may be prepared by reacting monomer or monomer blend under polymerization in conventional manners known a person of the art.

(14) Then, they can be obtained in form of powder, bead, suspension, inverse emulsion or liquid.

(15) In a preferred embodiment of the invention, water soluble or swellable polymers are homopolymers or copolymers of acrylamide.

(16) Acrylamide based polymers are obtained by polymerization of acrylamide and other water-soluble monomers with a ethylenically unsaturated moiety selected from the following families: Anionic monomers. They are advantageously selected in the groups comprising monomers with an acid carboxylic moiety (e: acrylic acid or methacrylic acid and their salts . . . ), monomers with a sulfonic acid moiety (ex: 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and its salts . . . ). Non-ionic monomers. They are advantageously selected in the group comprising methacrylamide, acrylamide derivatives likes N-alkylacrylamide, as for instance N,N-dimethylacrylamide or methylolacrylamide. vinylformamide, N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkyl(meth)acrylates and (meth)acrylates with an alkoxy chain can also been used. Cationic monomers. They are preferably selected in the groups comprising diallyldialkyl ammonium salts likes diallyldimethyl ammonium chloride (DADMAC) and dialkylaminoalkyl (meth)acrylates likes dimethylaminoethyl (meth)acrylate ((M)ADAME) and their acidified or quaternized forms by means known by the skill man of the art., and also dialkylaminoalkyl (meth)acrylamide and their acidified or quaternized forms likes the (meth)acrylamide propyl trimethyl ammonium chloride (((M)APTAC). Zwitterionic monomers can also been used. Anionic and cationic charges are associated on one single monomer. Example of zwitterionic monomers: sulfobetains likes sulfopropyl dimethylammonium ethylmethacrylate, sulfopropyl dimethylammonium propylmethacrylamide or sulfopropyl 2-vinylpyridinium, phosphobetains likes phosphato ethyl trimethylammonium ethylmethacrylate and carboxybetains.

(17) Preferably, water soluble or swellable polymers present in the composition of the invention are in powder or bead form.

(18) In a preferred embodiment of the invention, polymers are water soluble polymers.

(19) Preferably, molecular weight of water soluble polymers is above 500 000 g.Math.mol.sup.1 and preferably between 1 and 30 million g.Math.mol.sup.1, and more preferably above 5 million g.Math.mol.sup.1.

(20) Composition Description

(21) In the process of the invention a composition is applied by an aerial application.

(22) The composition has a particulate form and comprises at least one water soluble or swellable polymer and optionally at least one other component.

(23) The composition contains preferably between 20% and 100% and preferably between 50 and 100% by weight of water soluble or swellable polymers.

(24) Preferably, water soluble and swellable polymers are in powder or in bead form.

(25) To improve the spreading of the composition, the composition is in powder form and has a particle size between 0.1 and 10 millimeters, preferably between 0.5 and 4 millimeters. Particle size refers to the mean diameter measured with a laser particle sizer according conventional technics known by the skill man of the art. An example of device for measuring the mean diameter is the Mastersizer from Malvern Instruments.

(26) The composition is preferably in tablet or prill form.

(27) To improve spreading and polymer diffusion in the soil, the composition contains a filler or a binder.

(28) The filler is selected in a non-limiting manner, from alkali metal sulphate or chloride salts.

(29) The binder is not limited to a single component and might comprise functional components. Functional binders include pesticides, fertilizers, urea, various salts of inorganic and organics acids.

(30) Preferably the composition contains between 1 and 80% by weight of filler and more preferably between 10 and 50% by weight.

(31) Preferably the composition contains between 1 and 50% of binder and more preferably between 5 and 30% by weight.

(32) Other components of the composition can be agricultural active ingredients likes natural insecticides, insecticides with organic phosphorus, insecticides with carbamates, nematicides, sterilizing agents with organic chloride, sterilizing agents with organic phosphorus, other sterilizing agents, herbicides, rodenticides.

(33) Preferably, other components of the composition are in powder form.

(34) For an application of the composition by airway, the bulk density of the composition should be preferably between 300 and 1000 kg.Math.m.sup.3 and more preferably between 300 and 800 kg.Math.m.sup.3.

(35) Moreover, residual water content in composition should be the lowest to avoid particles agglomeration (polymers and other components). Preferably, residual water content of the composition in particulates should be lower than 15 weight percent.

(36) In a preferred embodiment, the composition is a single component which is a water soluble or swellable polymer in powder form.

(37) Process Description

(38) The process of the invention consists in aerial application to the soil of a composition in particulate form.

(39) Aerial application means application by any aerial mean but preferably applications are performed by airplane, helicopter, hang gliding, sailplane or drone.

(40) The ability to apply water soluble or swellable polymers in composition having a particulate form via an aerial application allows the producer to more readily use them and be much timelier in the application. The application allows for flexibility and reduce the amount of labour and equipment needed to use these polymers.

(41) In order to apply composition in particulate form by airplane, spreaders are attached to means of air transport. The spreader can be the agri-chemical spreader described in the filed patent U.S. Pat. No. 4,694,991.

(42) For a uniform application, the altitude of application of the particulate composition is preferably below 50 m and more preferably between 20 m.

(43) The amount of composition which is applied for each application to the soil is comprised between 0.1 and 500 kg.Math.ha.sup.1, preferably between 1 and 100 kg.Math.ha.sup.1 and more preferably between 10 and 50 kg.Math.ha.sup.1.

(44) The process of the invention is suitable for soil conditioning in agriculture, forestry, construction and civil engineering, mining, protection of rivers and delta against pollution, environmental conservation, water storage or transportation.

(45) If aerial application concerns soil conditioning in agriculture, this application occurs preferably in crops fields between planting and the subsequent first rain event or irrigation. This is the time in which the soil is least stable.

(46) After the first aerial application of the composition to the soil, the process of the invention comprises preferably additional applications. In this case, each aerial application is performed at least 20 days and not more than 40 days after the previous one.

(47) The process of the invention allows for the improvement in the application of water soluble and swellable polymer for soil erosion. Aerial application can be performed more rapidly and easily than previous methods.