Method for cleaning and preventing plugging in micro-irrigation systems

1. A method of cleaning a block of an irrigation system or protect the block of the irrigation system against corrosion, comprising:

introducing a cleaning formulation comprising water, a water-soluble organic acid having an anion that forms a water-soluble calcium salt, and a water-soluble phosphonate dispersant to irrigation water to form a dispersant-containing irrigation water, wherein introducing said cleaning formulation lowers a pH of said dispersant-containing irrigation water to 2.5 to 3.5, and said water-soluble phosphonate dispersant is present in an amount of from 0.0005 to 16 parts by weight per 100 parts by weight of the cleaning formulation;

distributing said dispersant-containing irrigation water throughout said block of said irrigation system;

allowing said dispersant-containing irrigation water to stand in said block of said irrigation system for a time period of from 3 to 24 hours; and

then flushing said block of said irrigation system.

2. The method of claim 1 , wherein said water-soluble phosphonate dispersant is a water-soluble orthophosphonate dispersant.

3. The method of claim 1 , wherein said water-soluble phosphonate dispersant is selected from the group consisting of 1-hydroxy ethylidene diphosphonic acid (HEDP), amino-tris(methylene phosphonic acid) (ATMP), and sodium, potassium and ammonium salts thereof.

4. The method of claim 1 , wherein said water-soluble organic acid has a pK(1)a of less than 4.0.

5. The method of claim 1 , wherein said water-soluble organic acid is formic acid.

6. The method of claim 1 , wherein distributing said dispersant-containing irrigation water throughout said block of said irrigation system comprises feeding the dispersant-containing irrigation water to the irrigation system to distribute the dispersant-containing irrigation water throughout the block of the irrigation system.

7. The method of claim 6 , wherein the dispersant-containing irrigation water is fed to the micro-irrigation system for a time period of from 40 to 60 minutes.

8. The method of claim 6 , wherein the irrigation system is a micro-irrigation system, and the dispersant-containing irrigation water is fed to the micro-irrigation system for a time period of from 40 to 60 minutes.

9. The method of claim 1 , wherein said cleaning formulation contains 0.005 to 20 parts by weight of said water-soluble phosphonate dispersant per 100 parts by weight of the water-soluble organic acid.

10. The method of claim 1 , wherein the cleaning formulation is introduced at a rate or level of from 1 to 10 kg of actives per acre served by the irrigation system.

11. The method of claim 1 , wherein the cleaning formulation contains from 10 to 80 parts by weight of the water-soluble organic acid per 100 parts by weight of the cleaning formulation.

12. The method of claim 11 , wherein the cleaning formulation contains from 20 to 60 parts by weight of the water-soluble organic acid per 100 parts by weight of the cleaning formulation.

13. The method of claim 1 , wherein the dispersant-containing irrigation water contains from 0.01 to 1.0 parts by weight of the water-soluble organic acid per 100 parts by weight of the dispersant-containing irrigation water.

14. The method of claim 1 , wherein the irrigation system includes (i) irrigation tubing that is above ground and (ii) emitters or micro-sprinklers.

15. The method of claim 1 , wherein the water-soluble calcium salt has a solubility in water of at least 2,000 ppm.

16. The method of claim 15 , wherein the solubility in water of the water-soluble calcium salt is over 5,000 ppm.

17. The method of claim 1 , wherein allowing said dispersant-containing irrigation water to stand in said block of said irrigation system removes or solubilizes deposits, keeps solids dispersed, or suspends particles in said block of said irrigation system.