Method of soil conditioning by application of water-soluble or water-swelling polymer

Abstract

Method of soil conditioning which consists in applying a water-soluble or water-swelling polymer to the soil, characterized in that: the polymer is prepared as a polymer-concentrated liquid, the preparation of obtained in this way is applied to the surface of a support rotating about its axis of revolution in order to form droplets which are spread on the soil.

Claims

1. A method of soil conditioning comprising applying a water-soluble or water-swelling polymer to the soil, characterized in that: the polymer is prepared as a polymer-concentrated liquid, the preparation obtained in this way is applied to the surface of a support rotating about its axis of revolution in order to form droplets which are spread on the soil, wherein the polymer-concentrated liquid is stored in a tank and then transported from the tank to the support by a feeding system, the feeding system being a flexible pipe and including a dosing pump; and further characterized in that the support is a disc or a cone.

2. The method according to claim 1, characterized in that the polymer-concentrated liquid includes at least one of water, oil and a solvent and a polymer whose concentration represents between 5 and 75% of the preparation weight.

3. The method according to claim 1, characterized in that the polymer concentrate is an aqueous dispersion, an emulsion, an inverse emulsion or a suspension.

4. The method according to claim 1 characterized in that between 0.1 and 500 kg of polymer per hectare is applied to the soil.

5. The method according to claim 1 characterized in that less than 5000 liters of water per hectare is applied to the soil.

6. The method according to claim 1, characterized in that the support is a disc or a cone provided with a raised edge.

7. The method according to claim 1 characterized in that the feeding system is a tank and the polymer concentrated liquid is contained in a tank under pressure.

8. The method according to claim 1 characterized in that the support, the tank and the feeding system are mounted on a pipe carried or towed by a motor-driven machine.

9. The method according to claim 1 characterized in that the water-soluble or water-swellable polymer is chosen from the group consisting of: Polymers and copolymers based on acrylamide, acrylic acid, acrylates, methacrylic acid, methacrylates, acrylonitrile, vinylpyrrolidone, vinylformamide, itaconic acid, vinyl acetate, maleic acid, glycol ethylene and the derivatives of these polymers. natural polymers, natural rubbers, polysaccharides and their derivatives: galactomannan, guar gum, carob gum, xanthane gum, arabic gum, chitosan, carrageen, pectines, starch, modified starch, alginates, celluloses, cellulose derivatives (cellulose ethers), agar-agar; and acrylamide starch and acrylamide copolymers, starch and acrylonitrile copolymers, chitosan and acrylic acid copolymers.

10. The method according to claim 1 characterized in that the polymer concentrated liquid is in the form of a dispersion of polymer containing between 5 and 50% by weight of water-soluble or water-swelling polymer.

11. The method according to claim 1 characterized in that the polymer concentrated liquid is in the form of a polymer emulsion containing between 20 and 55% by weight of water-soluble or water-swelling polymer.

12. The method according to claim 1 characterized in that the water-soluble polymer is a polymer based on acrylamide having an average molecular weight by weight in excess of 250,000 g/mol.

13. A method of soil conditioning comprising applying a water-soluble or water-swelling polymer to the soil, characterized in that: the polymer is prepared as a polymer-concentrated liquid, the preparation obtained in this way is applied to the surface of a support rotating about its axis of revolution in order to form droplets which are spread on the soil, wherein the polymer-concentrated liquid is stored in a tank and then transported from the tank to the support by a feeding system, the feeding system being a flexible pipe and including a dosing pump; and further characterized in that the support has striations or grooves on its surface, connecting the center of the support to its perimeter.

14. A method of soil conditioning comprising applying a water-soluble or water-swelling polymer to the soil, characterized in that: the polymer is prepared as a polymer-concentrated liquid, the preparation obtained in this way is applied to the surface of a support rotating about its axis of revolution in order to form droplets which are spread on the soil, wherein the polymer-concentrated liquid is stored in a tank and then transported from the tank to the support by a feeding system, the feeding system being a flexible pipe and including a dosing pump; and further characterized in that a polymer concentrated liquid is applied to the central part of the support near its axis of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of a support according to the invention.

(2) FIG. 2 is a schematic representation of application equipment including the support illustrated in FIG. 1.

(3) FIG. 3 is a schematic representation of a tractor equipped with the application equipment.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Equipment for Implementation of Method

(4) FIG. 1 is a representation of the support which is liable to be implemented within the method of the invention. The support is in the form of a rotating disk (1) with striations extending from the center to the outside (2) and a spindle (3). On contact with the rotating disk, the liquid is transformed into droplets of a variable size depending on the speed of rotation and the rheology of the concentrated polymer liquid.

(5) In FIG. 2, the remainder of the equipment required for the implementation of the method is depicted. The equipment includes a recipient (4) filled with a dispersion of polyacrylamide (5) and provided with an air venting device (6). It also includes a peristaltic pump (7) and a pipe (8) connecting the tank to the support (9).

(6) In FIG. 3, a tractor (10) is shown, carrying a ramp (11) fitted with 8 application equipment units (12) capable of conditioning large surface areas in a reasonable time.

Example 2

Example of Implementation of Method

(7) We attempted to spread 10 kg of polyacrylamide with a conventional agricultural sprayer over an area of almost 1 hectare. We then applied the same quantities of polymer using the method of the invention. The area to be treated was marked out on a larger plot of land in a 72 m wide and 139 m long rectangle, adapted to the size of the spraying machines, i.e. 24 m wide for the conventional sprayer and 12 m wide for the equipment assembled according to the method of the invention.

(8) In the first case, in an agricultural sprayer tank, we diluted an acrylamide copolymer (70% molar density) and sodium acrylate (30% molar density) powder, marketed by SNF SAS under the name of Flobond A30, to the extent of 300 ppm, i.e. a total quantity of mixture to be pulverized amounting to 33,333 liters. With the sprayer having a carrying capacity of 3000 liters, we decided to carry out 12 applications of 2778 liters of the 300 ppm acrylamide copolymer preparation. Each pass required the preparation of the mixture to be sprayed meaning that each time we were required to pour the acrylamide copolymer powder to be diluted slowly into the water of the sprayer tank while constantly stirring it, then to wait a maturation time of approximately 1 hour, while constantly stirring the mixture. Only then could the mixture be sprayed. Because the maximum flow rate of the sprayer is limited, we decided to carry out 3 successive passes at a speed of 5 km/h to spray all the mixture using the jet nozzles habitually used for the application of liquid fertilizers. The spraying of each 2778 liter mixture required approximately 20 minutes allowing for maneuvering. However, the filters of the sprayer had to be cleaned several times because they were easily fouled in the presence of at the dissolved acrylamide copolymer granules or insoluble particles. The time to prepare each mixture added to the time required for each of the 12 planned applications led us to realize that we would be unable to perform the complete operation in one day's work for a surface area of only 1 hectare, forcing us to abandon the operation under way. In addition, for the needs of this experiment, we were obliged to choose a plot of land having a water point to allow us to make up the mixtures. It appears even less possible to implement this method on a plot of land distant from a water point, or in areas where there is a shortage of water. In addition, applying 33,333 liters of water to 1 hectare of soil is a considerable undertaking that we would compare to irrigation. Furthermore, cleaning the spray and its tank called for large amounts of water because of the colloidal nature of the acrylamide copolymer. Accordingly, this method cannot be implemented reasonably.

(9) According to the method of the invention, we assembled a 12 m wide rig with the 12 rotary supports as described previously, each supplied with product by a flexible pipe connected to a single flexible pouch filled with the product to be spread, itself fitted with a coarse filter, placed in a rigid tank with each flexible pipe plugged into its own peristaltic pump mounted on the pipe alongside each rotary atomizer. By advancing at a speed of 7.5 km/hour, 40 liters of aqueous acrylamide copolymer dispersion (70% molar) and of sodium acrylate (30% molar) sold by SNF SAS under the name of SFA 30 (containing 25% copolymer) were applied in 10 minutes. When the operation was complete, the flexible pouch and the flexible pipes were discarded and the rotary supports disassembled then washed in running water.