Fertigation With Micro-Irrigation Micro-irrigation ... - Jan Hopmans

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Fertigation With Micro-Irrigation. Blaine Hanson ... Applications under Micro-Irrigation? ➢ Field wide variability. â—
MicroMicro-irrigation Fertigation With MicroMicro-Irrigation

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Blaine Hanson Jan Hopmans Annemieke Gardenas Department of Land, Air and Water Resources University of California, Davis

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Microsprinklers – trees, grapes Drip emitters – trees, grapes Drip tape – row crops

Jirka Simunek University of California, Riverside

FERTIGATION ¾

z z z z

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Objectives of Fertigation

Advantages Relatively uniform fertilizer applications Flexibility in timing of applications Less fertilizers used Reduced costs

Disadvantages z

z z

Potential contamination hazard from equipment malfunctions Backflow prevention devices required Careful handling of liquid fertilizers required

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Maximize profit by applying the right amount of water and fertilizer Minimize adverse environmental effects by reducing leaching of fertilizers and other chemicals below the root zone

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Maximizing Profit - Applying the Right Amount of Nitrogen ¾ ¾ ¾

Nitrogen requirements of the crop at each growth stage Nitrate concentrations in the irrigation water and the soil Amount of nitrogen in the fertilizer

What Contributes to Fertilizer Leaching Under MicroMicro-Irrigation? ¾ ¾ ¾ ¾

Adjusting for Nitrogen in Irrigation Water

Excessive fertilizer application Excessive water application Poor field wide uniformity of water and fertilizer applications Localized nonuniformity

Calculating the Injection Rate PN x A x 100 IR = PG x %C x IT

1 ppm N = 0.23 pounds of N per acre-inch of irrigation water

1 ppm NO3 = 0.051 pounds of N per acre-inch of irrigation water

IR = Injection rate (gallons per hour) PN = Pounds of nutrient per acre A = Acres PG = Pounds per gallon of fertilizer %C = Percent concentration of nutrient IT = Injection time (hours)

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What Affects the Uniformity of Fertilizer Applications under MicroMicro-Irrigation? ¾

Field wide variability z Varying injection rate z Varying emitter discharge rates

FieldField-wide Uniformity ¾

• Pressure variability • Clogging • Mixed emitters

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Travel time of chemical in pipelines, drip lines Localized variability – distribution of fertilizer in the soil around the drip line z

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Travel Times in Drip Line

Layout 60

Pump

Microsprinkler (13 gph) Drip Emitter (0.5 gph) TTape 5/8" TTape 7/8"

55 50 45 Travel Time (minutes)

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Maximum uniformity of fertilizer equals the uniformity of applied water Injection time must be sufficient for fertilizer to reach the furthermost part of the irrigation system Flushing time must be sufficient for fresh water to reach the furthermost part of the irrigation system Constant injection rate

40

600 ft

35

1300 ft Field A

30 25 20 15

Field B

10 5

600 ft

0 0

100

200

300

400

500

600

700

800

900

1000 1100 1200

Distance Along Lateral (feet)

3

300

50 Travel Times Total Time (minutes)

40 Elapsed Time (minutes)

Advance Recession

250

30

20

200

150 Fertilizer Application Time 100

50

10

Field A Field B

0 0

0 0

500

1000

1500

2000

2500

Distance (feet)

500

1000

1500

2000

2500

3000

Distance (feet)

3000

Injection time = 2 hours (starts one hour after start of irrigation)

Localized Nonuniformity under MicroMicro-irrigation Localized Nonuniformity – distribution of chemical around the drip line

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Soil water content decreases with distance and depth from the drip line Root density decreases with distance and depth from the drip line Chemical distribution may vary around the drip line, depending of chemical characteristics

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Soil Water Content – Drip Tape Subsurface Drip

Soil Water Content – Drip Tape

0

Surface Drip

Drip Line

Depth (inches)

-5 -10 -15 -20 0

5

10

15

20

25

30

35

40

40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10

-10 Drip Line -15 -20 -25 -30

Distance Across Bed (inches)

40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10

-5 Depth (inches)

0

0

5

10

15

20

25

30

35

40

Distance Across Bed (inches)

Soil Water Content – Drip Emitter

Soil Water Content - Microsprinkler

August 25, 1997 -10

Depth (inches)

-30 -40 -50 -60

Soil Moisture Content - Microsprinkler 0 40

Depth (feet)

38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22

-20

-1 35

-2 30

-3

0

1

2

3

4

5

6

7

Distance From Microsprinkler (feet)

8

9 25

-70 20

30

40

50

60

70

80

90

100

Distance From Tree (inches)

5

Drip Line

Drip Line

-5

Root Distribution With Depth - Tomatoes

-10

Drip Line 20

16

-20

14 -25 12 -30

10

-35

8 6

-40

1.6 1.4 1.2

-400

1

R

5

10

15

20

25

30

35

0.8

-600

0.6 0.4 0.2

-800

200

400

600

800

1000

1200

0

Distance (mm)

Soil Water Content – Drip Tape -45

1.8

18 Depth (mm)

Depth (inches)

-15

-200

1 foot = 300 mm

Distance Across Bed (inches)

Root Distribution Drip Irrigation

Tree Trunk

Root Distribution

Microsprinkler Irrigation

Tree Trunk

Wetted Area Wetted Area Low Root Density Low Root Density

High Root Density

High Root Density

Tree Skirt Tree Skirt

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Root Distribution Flood Irrigation

Tree Trunk Root Distribution -Citrus

Wetted Area

Low Root Density High Root Density Tree Skirt

Forms of Nitrogen

What Affects the Distribution of Fertilizer in the Soil? ¾

Nitrate z

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Type of fertilizer z z

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z

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z z

Soil type Emitter discharge rate Duration of irrigation

Fertigation strategy z z

Duration of fertigation Timing of injection relative to irrigation duration

z z z

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Negatively charged ion Moves readily through soil with water flow Preferred choice of N by most plants

Urea z

Water movement in the soil z

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Mobile – urea, nitrate Adsorbed – ammonium, potassium, phosphorus

z

Neutral molecule Highly soluble in water Moves readily in the soil with water flow Converts to ammonium and carbon dioxide

Ammonium z z z z

Positively charged ion Adsorbed to clay particles in the soil Does not move with water Converts to nitrate (rate at which depends on soil water content and temperature

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Fertigation Strategies

Injection Practices

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Short injection times z z

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¾

z

Common recommendations z Inject during middle 50% of irrigation cycle z Inject during middle third of irrigation cycle Observed practices – short injection times at various times during the irrigation cycle

z

z z

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Long injection times z z z z

z z

Drip Loam

180

Depth (cm)

140

180

180

180

160

160

160

0.375

140

140

140

120

120

120

0.325

120

0.275 100

0.225

100

100

100

80

0.175

80

80

80

0.125

60

60

60

60

40

40

40

0.075 40

0.025

20

20

20

T=0d 0

0

20

40

60

0

0

20

40

60

T = 0.70 d 80

0

0

20

40

Distance From Emitter (cm)

60

200

200

200

180

180

180

160

160

160

140

140

140

120

120

120

100

100

100

80

80

80

60

60

60

40

40

40

2 h - beginning

20

T = 0.13 d 80

Nitrate Concentrations

200

0.425

0.475

160

200

Depth (cm)

200

Middle oneone-third or oneone-half of the irrigation set time Relatively low chemical concentration in irrigation water May reduce precipitation problems May provide better chemical distribution throughout the root zone Flushing of drip lines may not be needed May not be convenient for irrigators

Drip Loam T = 1.5 d

Soil Water Content

200

1 to 2 hours of injection Relatively high chemical concentration in irrigation water May aggravate chemical precipitation problems May result in poor distribution of chemical throughout the root zone Flushing highly recommended Convenient for irrigators

20

80

0

0

20

40

60

80

0

2 h - middle

20

T = 1.5 d 0

20

40

60

80

0

20

40

60

80

2 h - end

20 0

0

200

0.47 0.43 0.39 0.35 0.31 0.27 0.23 0.19 0.15 0.11 0.07 0.03 -0.01 -0.05

0

20

40

60

180 160 140 120 100 80 60 40

Middle 50%

20 80

0

0

20

40

60

80

Distance From Emitter (cm)

8

Drip Silt Clay 200

200

200

180

180

180

180

160

160

160

140

140

140

0.47 0.43 0.39 0.35 0.31 0.27 0.23 0.19 0.15 0.11 0.07 0.03 -0.01 -0.05

140 120 100 80 60 40

120

120

120

100

100

100

80

80

80

60

60

60

40

20 20

40

180

160

160

140

140

120

120

100

100

80

80

60

60

40

40

140 120 100 80

2h-

40

20

20

T = 0.13 d 60

180

20

T=0d 0

200

180

40

20 0

200

60

40

80

0

0

20

40

T = 0.70 d 60

0

80

0

20

40

0

T = 1.5 d 60

0

80

Nitrate Concentrations

200

160

Depth (cm)

200

160

0

20

40

60

0

20

0.47 0.43 0.39 0.35 0.31 0.27 0.23 0.19 0.15 0.11 0.07 0.03 -0.01 beginning -0.05 40

60

2 h - middle

20 0

80

0

20

40

200

0

80

160 140 120 100 80 60 40

2 h - end

20

60

180

0.47 0.43 0.39 0.35 0.31 0.27 0.23 0.19 0.15 0.11 0.07 0.03 -0.01 -0.05

0

20

40

60

Middle 50%

20 0

80

0

20

40

60

80

80

Distance From Emitter (cm) Distance From Emitter (cm)

Subsurface Drip Loam

0.475 0.425

100

100

90

90

80

80

70

70

60

60

50

50

Nitrate Concentrations

100

100

0.3

90

90

0.26

80

80

70

70

60

60

50

50

40

40

30

30

0.22

Subsurface Drip Loam T = 1.15 d

0.18 0.14

40

40

30

30

0.1

20

20

0.06

10

10

0.02

10

-0.02

0

0

T=0 0

10

20

30

40

50

60

70

100

0

T = 0.13 d 0

10

20

30

40

50

60

70

100

Depth (cm)

Soil Water Content

Depth (cm)

Depth (cm)

Drip Silt Clay T = 1.5 d

Soil Water Content

20

20

10

2 h - beginning

0

0

10

20

30

40

50

60

70

100

100

100 90

90

90

90

90

0.375

80

80

80

80

80

0.325

70

70

70

70

70

0.275

60

60

60

60

60

50

50 40

0.225

50

50

50

0.175

40

40

40

40

30

30

30

30

20

20

20

10

10

0.125 0.075 0.025

10 0

T = 0.60 d 0

10

20

30

40

50

60

70

0

T = 1.15 d 0

10

20

30

Distance From Emitter (cm)

0

40

50

60

70

0

10

20

30

40

50

60

70

0

10

20

30

40

50

60

70

60

70

20

Middle 50%

10 0

10

30

20

2 h - end

2 h - middle 0

0

10

20

30

40

Continuous

10 50

60

70

0

20

30

40

50

Distance From Emitter (cm)

9

Surface Drip Sandy Loam T = 3.24 h

Depth (cm)

Nitrate Concentrations

0.47 0.43 0.39 0.35 0.31 0.27 0.23 0.19 0.15 0.11 0.07 0.03 -0.01 -0.05

0

0

-10

-10

-20

-20

-30

-30 -40

-40 -50

-50

0.5h - beginning 0

10

20

30

40

50

60

70

0

0

-10

-10

-10

-20

-20

-20

-30

-30

-30

-40

-40

-40

-50

-50

20

30

0

10

0

10

Middle 50% 40

50

60

70

20

30

40

50

60

70

50

60

70

-50

0.5h - end -60 10

0.5h - middle

-60

-60

0

0

Water Application Pattern of Microsprinkler

Continuous -60

-60 0

10

20

30

40

50

60

70

20

30

40

Microsprinkler

Distance Across Bed (cm)

0

Sprinkler Loam

Nitrate Concentrations

Soil Water Content

0

0

-50

-50

-100

-100

-50

Micro-sprinkler Sandy Loam T = 1.85 d

-150

2 h - beginning

0.475

-200

0.425 -150

-200

0

50

100

T = 0.13 d 150

200

250

300

0

-200

0

50

100

0.325 150

200

250

300

0

-50

0.275 0.225 0.125

-100

-150

-150

0.075 0.025

T = 0.88 d -200

0

50

100

T = 1.85 150

200

250

300

-200

0

-50

-50

-100

-100

-150

-150

0

50

100

150

200

250

0

50

100

150

200

250

300

0.26 0.22 0.18 0.14

0.175

-50

-100

0

0.3

0.375

T=0

Depth (cm)

Depth (cm)

-150

-100

-200 0

0

50

100

150

0.1

2 h - end

2 h - middle 200

250

300

-200

0 0

-50

-50

-100

-100

50

100

0.06 150

200

250

300

0.02 -0.02

300 -150

-150

Middle 50%

Distance From Sprinkler (cm) -200

0

50

100

Continuous 150

200

250

300

-200

0

50

100

150

200

250

300

Distance from Emitter (cm)

10

Phosphorus

Recommendations ¾ ¾ ¾ ¾

Do not start injection until irrigation water has reached the furthermost emitters Inject for sufficient time for the chemical to reach the furthermost emitters After injection, flush system with irrigation water until the fresh water reaches the furthermost emitters Maintain high uniformity of emitter discharge rates throughout irrigation system z

z z

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Other Considerations Frequency of applications z

z

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Little information on effect of injection frequency on crop yield No strong trend

FertilizerFertilizer-fertilizer interactions FertilizerFertilizer-irrigation water interactions

Avoid long periods of water application after injection of fertilizers or chemical

50 Red Fruit Yield (tons/acre)

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Minimize pressure variation (pressure(pressure-compensating emitters, pressure regulation, appropriate drip line lengths) Use same emitter sizes Prevent or correct clogging problems

Processing Tomatoes (weekly fertigation)

40

30

20

10

0 Daily

2/wk

1/wk

Irrigation Frequency

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Reactions Reactions (continued) ¾

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CalciumCalcium-based fertilizers (CN(CN-9, CANCAN-17) - can cause calcium carbonate precipitation if more than 2 to 3 meq/l of bicarbonate is in the irrigation water Phosphorus fertilizers - can cause calcium and magnesium phosphate precipitation if more than 40 to 50 ppm (2 to 2.5 meq/l) of calcium and magnesium is in the irrigation water

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¾

Mixing a fertilizer containing calcium with a fertilizer containing sulfate can cause gypsum to precipitate Mixing fertilizers can be tricky - use jar test and UNOCAL guidelines

Injection Equipment ¾

Batch Tanks z z

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Venturi Devices z z

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Inexpensive, easy to use Chemical mixture becomes more and more diluted with time Requires pressure difference Inexpensive, easy to use

Positive Displacement Pumps z z z z

Piston, diaphram Electric, gasoline, waterwater-driven Injects at constant rate Expensive

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Have a good day!!

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