Method and composition for preventing plugging in micro-irrigation systems

1. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil with irrigation water having a pre-additive precipitation factor of from 125 to 1,000 ppm, wherein said precipitation factor is a combined level of total alkalinity (as CaCO 3 ) in ppm and total hardness (as CaCO 3 ) in ppm, without plugging of a micro-irrigation system, comprising the steps of:

(step 1) adding a phosphate fertilizer to said irrigation water at a level of 40 to 2,100 ppm fertilizer phosphate (as P2O5) as a chaser to an addition of a combination of

a water-soluble organic acid selected from the group consisting of formic acid and the ammonium, potassium and sodium salts thereof, and

a water-soluble organophosphonate selected from the group consisting of compounds of Formulas I and II,

wherein x is either zero or one and wherein each M is a water-soluble cation independently selected from the group consisting of hydrogen, ammonium, potassium and sodium,

to said irrigation water,

said combination of said organic acid and said organophosphonate comprising a dosage of said organic acid of

ac.dos (in ppm)=pf (in ppm)/>7 and <70

wherein ac.dos is the dosage of said water-soluble organic acid and pf is said precipitation factor of said irrigation water, and

a dosage of said organophosphonate of

op.dos (in ppm)=pf (in ppm)/>50 and <500

wherein op.dos is the dosage of said organophosphonate and pf is said precipitation factor of said irrigation water;

(step 2) then feeding said irrigation water through said micro-irrigation system; and

(step 3) then allowing said micro-irrigation system to deliver said irrigation water to said agricultural soil.

2. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein said step 1 is comprised of:

(step 1.1) adding said phosphate fertilizer, said organic acid and said organophosphonate simultaneously to said irrigation water.

3. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein step 1 is comprised of:

(sub-step 1a) adding said organic acid and said organophosphonate to said irrigation water; and

(sub-step 1b) then adding said phosphate fertilizer to said irrigation water.

4. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein step 1 is comprised of:

(sub-step 1c) adding said organic acid to said irrigation water; and

(sub-step 1d) then adding said organophosphonate and said phosphate fertilizer simultaneously to said irrigation water.

5. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein step 1 is comprised of:

(sub-step 1e) adding said organophosphonate to said irrigation water; and

(sub-step 1f) then adding said organic acid and said phosphate fertilizer simultaneously to said irrigation water.

6. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein said organophosphonate is selected from the group consisting of amino-tri(methylene phosphonic acid) and 1-hydroxyethylidene-1,1-diphosphonic acid and the ammonium, potassium and sodium salts thereof.

7. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1

wherein said organophosphonate is selected from the group consisting of amino-tri(methylene phosphonic acid and 1-hydroxyethylidene-1,1-diphosphonic acid) and the ammonium, potassium and sodium salts thereof.

8. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 1 wherein said water-soluble organic acid and said water-soluble organophosphonate comprise an additive, and wherein step 1 is comprised of:

(sub-step 1g) adding a portion of said additive to said irrigation water; and

(sub-step 1h) then adding the remainder of said additive and said phosphate fertilizer simultaneously to said irrigation water.

9. A method of simultaneous micro-irrigation and phosphate fertilization of agricultural soil according to claim 7 wherein said water-soluble organic acid and said water-soluble organophosphonate comprise an additive, and wherein step 1 is comprised of:

(sub-step 1g) adding a portion of said additive to said irrigation water; and

(sub-step 1h) then adding the remainder of said additive and said phosphate fertilizer simultaneously to said irrigation water.

10. A stabilized agricultural micro-fertigation water comprising:

agricultural irrigation water having a pre-additive precipitation factor of from 125 to 1,000 ppm, wherein said precipitation factor is a combined level of total alkalinity (as CaCO 3 ) in ppm and total hardness (as CaCO 3 ) in ppm;

a water-soluble organic acid selected from the group consisting of formic acid and the ammonium, potassium and sodium salts thereof, at a concentration of

ac.dos (in ppm)=pf (in ppm)/>7 and <70

wherein ac.dos is the dosage of said water-soluble organic acid and pf is said precipitation factor of said irrigation water;

a water-soluble organophosphonate selected from the group consisting of compounds of Formulas I and II,

wherein x is either zero or one and wherein each M is a water-soluble cation independently selected from the group consisting of hydrogen, ammonium, potassium and sodium, at of concentration of

op.dos (in ppm)=pf (in ppm)/>50 and <500

wherein op.dos is the dosage of said organophosphonate and pf is said precipitation factor of said irrigation water; and

a phosphate fertilizer at a concentration of 40 to 2,100 ppm fertilizer phosphate (as P2O5),

prepared according to step 1 of the method of claim 1 .

11. A stabilized micro-fertigation water according to claim 10 , wherein said organophosphonate is selected from the group consisting of amino-tri(methylene phosphonic acid and 1-hydroxyethylidene-1,1-diphosphonic acid) and the ammonium, potassium and sodium salts thereof.