dr. juan enciso associate professor baen department texas...

Fertigation

Dr. Juan EncisoAssociate ProfessorBAEN Department

Texas Agrilife Research and ExtensionTexas A&M University System

Objectives

1. Importance of Irrigation Uniformity on Fertigation2. Inyector and inyection rates3. Rules of injection

Dr. Juan Enciso,Associate Professor

Texas AgriLife Research & Extension,Texas A&M University System

Irrigation systems in the LRGV

Earth ditches33%

Gated pipe10%

Poly-pipe52%

Drip3%

Sprinkler2%

Laser levelled 67% Dr. Juan Enciso,Associate Professor


Requires filtering system

Subsurface drip irrigation



Wetting pattern shapes and

fertilizer extraction

Loam



Fertigation requires high irrigation uniformity



Center pivot

Uniformity over 95% Dr. Juan Enciso,Associate Professor


Side roll-lateral movement

Uniformity 80%Dr. Juan Enciso,

Associate ProfessorTexas AgriLife Research & Extension,

Texas A&M University System

Surface irrigation



Uniformity 50-75%

Earth ditches versus poly-pipe



Surge irrigation

Cotton and sugarcaneCotton and sugarcane Dr. Juan Enciso,Associate Professor


Border irrigation-graded border

Uniformity 50%-70%Dr. Juan Enciso,



Big gun- traveler

High Energy cost

Very portable



Venturi injectors require a pressure differential. A booster pump is recommended

fertilizer Fertilizer + water



Venturi



Acid injection

Water high in bicarbonateInject acid to lower pH to 6.5-7.0 Dr. Juan Enciso,



Controlling the inyected amount.

Hose on the suction of the fertilizer tank

Dr. Juan Enciso,Associate ProfessorTexas AgriLife Research & Extension,Texas A&M University System

Rules of injection

Check for mixing and compatibility

Jar test

Best to make a small quantity to test fertilizer before preparing large batches



Plugging potential of irrigation water

Physical Suspended solidsDr. Juan Enciso,




Chemical Manganese-iron oxides sulfidesCalcium and magnesium precipitation



BiologicalBacteria


AlgaeRoot intrusion - buried emitter




Low Moderate SevereChemical

pH

Bicarbonate (ppm)

< 7.0 7.0-8.0 >8.0

< 100.0Iron (ppm)Sulfides (ppm)

< 0.2 0.2-1.5 > 1.5< 0.2 0.2-2.0 > 2



Common constituents of irrigation water

CationsAmonium NH4

Calcium Ca

Hidrogen H

Magnesium Mg

Sodium Na

Potasium K

AnionsBicarbonate HCO3

Carbonate CO3

Nitrate NO3

Phosphate PO4

Sulfate SO4Dr. Juan Enciso,



Plugging prevention (chemicals used)

Chlorine

Acid

SulfuricPhosphoricUrea-sulfuric (NpHuric)Citric acid



Calcium and magnesium precipitation

Carbonate precipitation Plug emitter

Use of ACID to LOW pH to 6.5

Sulfuric or white phosphoric

Last third of the irrigation set timeDr. Juan Enciso,



Acid injection

Water high in bicarbonateInject acid to lower pH to 6.5-7.0 Dr. Juan Enciso,



Rules of injection

Inject acids downstream

Inject other chemicals upstream of the filter ----

discontinue the application during the flushing process



Calcium and magnesium precipitation

If there are more than 50 ppm of Ca

Phosphoric acid should not be injected



Rules of injection

Only fertigate during the middle half of the irrigation set

1/4 1/2 1/4



Chlorine

Low concentration (1 to 5 ppm)Act as bactericide

Oxidizer of ironHigh concentration ( 100 to 1000 ppm)

Oxidizing agent for organic matter

Disintegrate organic matter Dr. Juan Enciso,Associate Professor


Monitoring soil moisture and fertilizer movement



Future studies

1 ft

1 ft

1 ft1 ft



Extraction tubes - monitor leaching, soluble elements



Arroyo Colorado

2202



Mixing rules

ALWAYS fill the mixing container with 50-75% required water

When used in the mix of dry soluble fertilizers

# 1



Mixing rules

ALWAYS add the ingredients slowly with circulation or agitation to prevent of large, insoluble or slowly lumps

# 2



Mixing rules

ALWAYS put acid into water

Not water into acid

# 3

Water can boil and spit dangerously



Mixing rules

DO NOT COMBINE Phosphoric acid with any calcium fertilizer

Calcium phosphates

Plug the irrigation system

# 4



Mixing rules

DO NOT mix sulfate with calcium

Insoluble calcium will form

# 5



Mixing rules

Extreme hard water (Ca and Mg)

Phosphates and sulfates

Insoluble compounds

# 6



Mixing rules

NEVER mix or store acids and

chlorine together

A toxic chlorine gas will form

# 7



Mixing rules

ALWAYS check with supplier about insolubility and incompatibility

# 8



Estimated Daily Water Use for Grain Sorghum

0.0

0.1

0.2

0.3

0.4

Days after planting

Inch

es

Leaf

Rapid growth

Boot Bloom

Grain fill Drying

24 50 70 80 120Dr. Juan Enciso,Associate Professor


Cation-Anion BalanceTotal number of cations = Number of anions

Source of nutrition Cations Anions

NH4 + 8 NH4

+

4 K + 9 H2PO4-

1 Ca 2+ 3 SO42-

1 Mg2+ 1 Cl-

Sum of charges 16+ 16- Dr. Juan Enciso,Associate Professor


Cation-Anion Balance

Source of nutrition Cations Anions

NO3 - 8 NO3

-

8 K + 5 H2PO4-

2 Ca 2+ 1 SO42-

2 Mg2+ 1 Cl-

Sum of charges 16+ 16-



Irrigation controller



Irrigation controller with solar panel



END



dr. juan enciso associate professor baen department texas...

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