LOCALIZED IRRIGATION METHOD

Abstract

The invention relates to a method for the localized irrigation of crops or planted areas whereby at least one water-soluble polymer having a molecular weight between 10,000 and 500,000 Da and containing at least one acrylamide or methacrylamide monomer is injected into the irrigation water intended for supplying a stationary localized irrigation device.

Claims

1-11. (canceled)

12. A method for the localized irrigation of crops or planted areas wherein at least one water-soluble polymer having a molecular weight between 10,000 and 500,000 Da and containing at least one acrylamide or methacrylamide monomer is injected into irrigation water intended for supplying a stationary localized irrigation device.

13. The method according to claim 12, wherein the at least one water-soluble polymer has a molecular weight between 25,000 and 300,000 Da.

14. The method according to claim 12, wherein the at least one water-soluble polymer is added to the irrigation water under conditions such that the weight concentration of the at least one water-soluble polymer in the irrigation water is between 0.1 ppm and 500 ppm.

15. The method according to claim 12, wherein the at least one water-soluble polymer is injected into the irrigation water in the form of an aqueous solution, wherein the at least one water-soluble polymer is present in the aqueous solution at a concentration between 10 and 60% by weight.

16. The method according to claim 12, wherein the at least one water-soluble polymer contains at least 50 mol % of the acrylamide monomer or methacrylamide.

17. The method according to claim 16, wherein the at least one water-soluble polymer further contains from 1 to 50 mol % of at least one anionic monomer.

18. The method according to claim 17, wherein the at least one anionic monomer of the at least one water-soluble polymer comprises acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, 2-acrylamido-2-methylpropane sulfonic acid, vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, allylphosphonic acid, styrenesulfonic acid, or water-soluble alkaline metal, alkaline-earth metal, or ammonium salts thereof.

19. The method according to claim 12, wherein the at least one water-soluble polymer is non-ionic.

20. The method according to claim 12, wherein the at least one water-soluble polymer contains a cationic monomer of the acrylamide, acrylic, vinylic, allylic or maleic type having a quaternary amine or ammonium function.

21. The method according to claim 20, wherein the at least one water-soluble polymer comprises dialkylaminoethyl acrylate (ADAME), dialkylaminoethyl methacrylate (MADAME), quaternized or in salt form, diallyl dimethyl ammonium chloride (DADMAC), acrylamido-propyl trimethyl ammonium chloride (APTAC) and methacrylamido-propyl trimethyl ammonium chloride (MAPTAC).

22. The method according to claim 12, wherein the localized irrigation system is a drip system.

23. The method according to claim 12, wherein the water-soluble polymer is injected directly in line into an irrigation water pipe.

Description

[0049] The invention and resulting benefits will become clear from the following examples supported by the attached FIGURE.

[0050] FIG. 1 is a graph showing the moistening height (cm) of soil samples as a function of time (h) in a buildup test by capillarity.

EXAMPLE 1: BUILDUP TEST BY CAPILLARITY IN SOIL COLUMNS

[0051] Soil samples defined as sandy fibrous clay according to the Aisne texture triangle are dried, ground and screened in order to remove elements therefrom with a size larger than 3 mm before being placed in 5 transparent PVC tubes (height: 24 cm, diameter 45 mm).

[0052] Each tube is provided at the bottom thereof with a large mesh filter made from stainless steel covered by a layer of 1 cm of filter gravel. The soil samples are next packaged into the tubes, then moistened maximally before being dried in an oven in order to obtain structured soil samples. Each soil column then has a height of 18 cm.

[0053] For each of the columns, the base is next partially vertically submerged within an aqueous solution (solutions 1 to 5 below) such that the first lower 2.5 cm of each soil column is submerged within the aqueous solution. As the water is sucked through the soil column, the level of the aqueous solutions is kept at a constant level.

[0054] Solution 1:

[0055] Water

[0056] Solution 2:

[0057] Aqueous solution containing 12.5 ppm of an acrylamide and sodium acrylate copolymer A in water. The polymer contains 8 mol % of sodium acrylate. This solution is obtained by means of the dilution of a parent solution of the polymer with a weight concentration of 40%. The molar mass of the polymer is about 200,000 Da (intrinsic viscosity: 1.18 dL/g, at 20 C., in a 1 M solution of NaCl at pH 7.0).

[0058] Solution 3:

[0059] Equivalent to solution 2, with the sole difference that the aqueous solution contains 200 ppm of polymer A.

[0060] Solution 4:

[0061] Aqueous solution containing 12.5 ppm of an acrylamide and sodium acrylate copolymer B in water. The polymer contains 30 mol % of sodium acrylate. This solution is obtained by means of a polymer dispersion with a weight concentration of polymer of 15%. The molar mass of the polymer B is about 12 million Da (intrinsic viscosity: 17.75 dL/g, at a 20 C., in a 1 M solution of NaCl at pH 7.0).

[0062] Solution 5:

[0063] Equivalent to solution 3, with the sole difference that the aqueous solution contains 200 ppm of polymer B.

[0064] FIG. 1 shows the moistening height (cm) of the soil samples as a function of time (h). The zero point is the surface of the aqueous solution.

[0065] The buildup of the water by capillarity is essential in order to guarantee the effectiveness of a buried drip irrigation system. Yet the fastest diffusion is shown to occur for the solutions containing polymer A (polymer representative of the polymer used in the inventive method).

EXAMPLE 2: CLOGGING RISK TEST

[0066] A synthetic irrigation water is prepared by doping potable water taken from the distribution grid with 160 mg/L of kaolin and 27 mg/L of CaCl.sub.2. This synthetic irrigation water would, due to the quantity of matter in suspension, be ranked 10 on a scale up to 20 as established by Bucks, Nakayama and Gilbert in 1979 (Agricultural Water Management, 2, 1979, p. 149-162).

[0067] 5 parent solutions of different acrylamide and sodium acrylate copolymers are prepared in order to obtain concentrated solutions at 0.1 g/L (copolymers A to E in Table 1).

TABLE-US-00001 TABLE 1 List of polymers. Form Anionicity Molecular weight Polymer A Concentrated liquid 8% 200,000 Da Polymer B Suspension 30% 12,000,000 Da Polymer C Reverse emulsion 30% 20,000,000 Da Polymer D Powder 30% 15,000,000 Da Polymer E Powder 10% 12,000,000 Da Remark: polymers A and B are those of example 1.

[0068] 2 ml of each parent solution is doped in 5 different beakers at 500 ml of the synthetic irrigation water initially prepared. A 6.sup.th beaker containing only 500 ml of synthetic water is also prepared. The 6 beakers are plugged in order to be turned over simultaneously 20 times, then left to rest.

[0069] In less than 5 minutes, flocks form in the beakers containing polymers B, C and D. It is not possible to distinguish flocks in the beakers containing the irrigation water alone and the irrigation water doped with polymer A.

[0070] The content of each beaker is next poured through a sieve filter with a 130 m mesh. This mesh size is commonly used to filter water intended for a drip irrigation system (Irrigazette, No. 146, 2015, p 10-15 The origins of filter use in agriculture).

[0071] The retentate is next recovered by washing the filter with demineralized water, then placed in the dryer to quantify the dry matter retained by the filter.

TABLE-US-00002 TABLE 2 Dry matter of the retentate Trial Retentate mass (mg) Synthetic irrigation water Not measurable Synthetic irrigation water + 0.4 ppm of polymer A Not measurable Synthetic irrigation water + 0.4 ppm of polymer B 33.5 Synthetic irrigation water + 0.4 ppm of polymer C 12.3 Synthetic irrigation water + 0.4 ppm of polymer D 20.0 Synthetic irrigation water + 0.4 ppm of polymer E 29.2

[0072] The matter in suspension contained within this synthetic irrigation water is therefore not retained through a filtration system commonly used for a localized irrigation system such as a drip irrigation system.

[0073] The addition of polymer A, which is representative of the polymer used in the method according to the invention, unlike the other polymers representative of the prior art, does not cause the formation of flocks with a size exceeding 130 m, which could clog the emission orifices of a localized irrigation device such as a drip irrigation device.

[0074] Polymers B, C, D and E, representative of polymers used in the prior art, cause the clear formation of flocks with a size exceeding 130 m, which could clog the emission orifices of a localized irrigation device such as a drip irrigation device.

EXAMPLE 3: HORIZONTAL SURFACE DIAMETER OF THE MOISTENING BULB FOR A SURFACE DRIP SYSTEM

[0075] 40 cm of soil is placed in 36 plastic cubic trays (depth: 90 cm, side: 60 cm). This soil is of the fibrous sandy type according to the Aisne texture triangle. The soil has previously been dried, then screened to remove the elements larger than 3 mm therefrom.

[0076] Each tray is pierced all the way through, at the height of the soil surface, to allow the passage of a drip irrigation pipe, from one to the next through the different trays, such that an emission orifice is positioned at the center of each of the trays. The device is repeated three times per lot of 12 trays.

[0077] The polyethylene drip pipe line is of the UNIRAM type (provided by the Company NETAFIM). The drip pipes are self-regulating and have a flow rate of 0.7 dm.sup.3/h (0.7 L/h).

[0078] Three irrigation solutions are prepared:

[0079] Solution 1:

[0080] Water (water from the distribution grid).

[0081] Solution 2:

[0082] Aqueous solution containing 12.5 ppm of copolymer A.

[0083] Solution 3:

[0084] Aqueous solution containing 12.5 ppm of copolymer B.

[0085] Each aqueous solution is distributed through the pipe provided with drip pipes at a pressure of 0.15 MPa (1.5 bar), using a membrane pump, for 2 hours.

[0086] After two hours of irrigation, for each irrigation bulb, the surface diameter is measured longitudinally and orthogonally to the drip irrigation pipe. The calculated mean diameter of the surface irrigation bulbs is then the mean of these longitudinal and orthogonal diameters.

[0087] The mean diameter of the 12 surface irrigation bulbs for each of the three solutions is then calculated to lastly obtain a mean for the 12 irrigation bulbs.

[0088] The obtained results are then expressed in terms of an increase in the diameter of the irrigation bulb, using, as reference, the mean surface diameter for the irrigation bulbs obtained using the solution 1 (Table 3).

[0089] By squaring the comparison, the estimated gain is expressed in terms of an increase in the moistening surface.

TABLE-US-00003 TABLE 3 Obtained gains Type of Gain Solution 2 (Polymer A) Solution 3 (Polymer B) Increase in diameter +18.1% +24.4% Increase in surface area +39.4% +54.7%

[0090] Polymer A, representative of the polymer used in the inventive method, makes it possible to achieve the objective of increasing the horizontal diffusion of water from the irrigation bulb.

[0091] Solution 3 (Polymer B) required the intermediate preparation of a 1 g/L polymer solution to ensure the proper dilution of the latter. This intermediate solution was then added to the water from the tank intended for the irrigation. All of the steps for the preparation of solution 2 lasted 2 hours.

[0092] Solution 2 (Polymer A) was prepared in a single step by directly adding the polymer in concentrated solution to the water intended for the irrigation. The sole agitation generated by the tank return of the membrane pump allowed the preparation of solution 3 in 10 minutes.