The effects of drip irrigation methods

The Effects of Drip Irrigation Methods on Plasticulture

Tomato Yield and Quality in South-Central Kentucky

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Dr. Tim Coolong – University of Kentucky Department of HorticultureDr. Martin Stone – Western Kentucky University Department of Agriculture

Role of Water in Tomato Production

Production Cost - 1/3

Limited natural resource

‘How Much to Apply’? Just enough to be productive Not a drop extra

General Guidelines exist but dependent on Local conditions Seasonal variation

Experimental Details

Conducted at WKU farm

Bowling Green, Ky.

Summer 2010 -2011

Plasticulture• Black• Drip irrigation• Fertigation• Staked

‘Mountain Fresh Plus’

Experimental Design

Randomized Complete Block

4 replications

4 treatments

Statistical Analysis – SAS p < 0.05 Means separated by Duncan’s MRT if sig. F test

Treatments

ID 36 – University of Kentucky Recommendation

Acre Inch per Week

½ ID 36

Water Balance Method Pan Evaporation at Nolin Lake Dam, ACOE Crop Coefficient, Source: Tekinel and Çevik (1993) Computed Water needs Weekly =

• Water Balance Method

How Much to Apply?

UK recommendation for tomatoes ID 36 Extension Publication

• May overestimate water demands

• Original source of information unknown

Farmers apply 1 acre inch water/week Standard crop recommendation Based on ‘Farmer Knowledge’

Water Balance Method

Most efficient method based on Stage of crop growth

• Transplant vs. fruiting Environmental conditions

• Drives demand for water

Water Balance Method

Pan Evaporation Data Affect plant Transpiration Temperature, humidity, solar radiation and wind

Crop Coefficient Crop specific Model of Water use through crop growth stages Based on actual data

Determine weekly tomato water usage

Crop Coefficient Model

Tekinel and Çevik (1993)

Actual Crop Coefficients and Pan Evaporation

1 3 5 7 911 13

0

0.5

1

weekly pan

Weeks After Transplanting

Hypothesis

Standard recommendations overestimate water needs of tomatoes Over/under estimate needs through season

Reduction of water usage will not reduce yield and quality

Water Manipulation

Checked measured by water meters on each treatment

Metered by gallon

Three treatments were altered weekly for water supply ID 36 ½ ID 36 Water Balance Method

Confirmation by meters and

tensiometers

1 2 3 4 5 6 7 8 9 10 11 12 13 14

0

100

200

300

400

500

Weekly Water Distribution

ID 36

Acre Inch Week

1/2 ID 36

Water Balance

Weeks after Transplanting

Gal

lons over

over

under

100%

71%

54%

73%

Cumulative Water Usage

ID 36

Acre Inch Week

1/2 ID 36

Water Balance

Weeks After Transplanting

Tensiometers

Detect soil water potential related to soil water content “dummy root” Used to confirm accuracy of water applied

• Readings 0–10: Saturated soil• Readings 70 and higher: Stress range

Each treatment Opposite drip irrigation lines ½ way between plants 30 cm deep

Read weekly

19-M

ay

28-M

ay

6-Ju

n

15-Ju

n

24-Ju

n

3-Ju

l

12-Ju

l

21-Ju

l

30-Ju

l

8-Aug

17-A

ug

0

10

20

30

40

50

60

70

80

90

ID 36Acre-Inch Wk1/2 ID 36Water Balance

Weeks After Transplanting

Soil

Wat

er T

ensi

on (c

entib

ars)

WEEKLY TENSIOMETER READINGS

Wetter

Stress Range

Harvest

Weekly for 7 weeks - (7/12)

‘Breaker’ stage = harvest

Sorted by USDA grades Quality

• Marketable – Unmarketable (Cull) Size

• Small, medium, large, extra large Weighed - (lbs) Noted radial cracks

Table 1. The effects of four irrigation treatments on marketable yield and yields of small, medium, large, and extra-large fruit as well as percent of culls of Mt. Fresh Plus tomatoes grown in Bowling Green, Ky., in 2010. Treatments are ordered based on marketable yield (highest to lowest).1

Conclusion

Based upon one years data

we can produce as many quality marketable tomatoes with less irrigation ½ the high recommended volume irrigation significantly influences yield data suggest that water distribution may play just as important role as volume

• Ex: Treatments of Acre Inch Week and Water Balance Method

over

over

under