IRRIGATION WATER SUPPLY
27,225 gallons/acre inch
Gallons/Min/Acre
Acre Inches/Day
1.0
0.053
2.0
0.107
3.0
0.160
4.0
0.214
5.0
0.267
6.0
0.320
7.0
0.373
SOIL WATER DATA
TEXTURE
FIELD
CAPACITY
Inches/foot
PERMANENT
WILTING POINT
Inches/foot
4.38
3.05
1.33
0.80
0.21
3.86
2.36
1.50
0.90
0.77
3.25
2.03
1.22
0.73
1.28
AMARILLO
FINE SANDY
LOAM
2.88
1.90
0.98
0.59
1.84
PATRICIA &
AMARILLOL
OAMY FINE
SAND
2.60
1.62
0.98
0.59
5.79
PULLMAN
CLAY LOAM
OLTON
LOAM
ACUFF
LOAM
PLANT
AVAILABLE
WATER
Inches/foot
INITIATION OF
STRESS
60% depletion
of PAW
INFILTRATION
RATE
Inches/hour
0.00
25-Sep
18-Sep
11-Sep
4-Sep
28-Aug
21-Aug
14-Aug
7-Aug
31-Jul
0.45
24-Jul
0.50
17-Jul
10-Jul
3-Jul
26-Jun
19-Jun
12-Jun
5-Jun
29-May
22-May
15-May
8-May
1-May
INCHES/DAY
2013 DAILY PET BY LOCATION
CANYON
TULIA
LUBBOCK
LAMESA
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
CROP COEFFICIENTS-COTTON
1.20
30 Inch Rows
40 Inch Rows
CROP WATER USE/PET
1.00
0.80
0.60
PEAK FLOWER
0.40
FIRST MATURE BOLL
50%OPEN BOLLS
0.20
FIRST SQUARE
0.00
100
300
500
700
FIRST FLOWER
900
1100
1300
1500
1700
ACCUMULATED HEAT UNITS
1900
2100
2300
2500
25-Sep
18-Sep
11-Sep
4-Sep
28-Aug
21-Aug
14-Aug
7-Aug
31-Jul
24-Jul
17-Jul
10-Jul
3-Jul
26-Jun
19-Jun
12-Jun
5-Jun
29-May
22-May
3000
ACC HEAT UNITS
2500
0.20
1500
0.15
1000
0.10
500
0.05
0.00
DAILY CROP WATER USE
0
15-May
ACCUMULATED HEAT UNITS
2013 COTTON WATER USE
0.35
DAILY CROP WATER USE
0.30
0.25
2000
CORN & SORGHUM CROP WATER USE
1.20
CORN
SORGHUM
CROP COEFFICIENT (CWU/PET)
1.00
0.80
0.60
0.40
0.20
0.00
0
15
30
45
60
75
DAYS AFTER PLANTING
90
105
120
135
DAILY & SEASONAL CROP WATER USE
CROP
MAXIMUM
DAILY
WATER USE
VOLUME
REQUIREMENT
DURATION
(Days)
SEASONAL
WATER USE
(Inches)
(GPMA)
(Inches)
COTTON
0.25
5
40
22-24
CORN
0.35
7
60
32-35
SORGHUM
0.30
6
40
28-30
WHEAT
0.25
5
75
20-22
PEANUTS
0.30
6
70
30-32
Critical Developmental Stages
• Corn: Two weeks prior to tasseling is the most critical period when
establishing number of rows and kernels/row Tasseling & Silking, Water
Stress and High Temperature desynchronize pollen shed and silk
receptivity Early seed fill, Reduced supply of photosynthate results in
kernel abortion
• Cotton:
First square to first flower establishes number of harvestable
fruit. First flower through fourth week of flowering establishes
harvestable boll number Bolls less than 5 days old are sensitive to water
and nutrient stress causing abortion
• Sorghum:
Panicle initiation through boot and heading affects
seed/head, Water Stress during early grain fill through dough stage
affects seed size
• Peanuts: Dry surface soil at pegging affects pod number, Water
Stress during Pod Fill affects kernel number and size
COTTON WATER USE EFFICIENCY
TEXAS HIGH PLAINS
1800
1600
LINT YIELD (Pounds/acre)
1400
75-100 pounds/inch
1200
1000
800
40-50 pounds lint/inch
600
10-12 INCHES OF IRRIGATION WATER
HIGH EFFICIENCY APPLICATION
400
AVERAGE GROWING SEASON RAIN
200
0
0
2
4
6
8
10
12
14
16
WATER SUPPLY (Inches)
18
20
22
24
26
BIOLOGICAL-ECONOMIC
WATER USE EFFICIENCY
CROP
INTERCEPT
SLOPE
160 SEED COTTON
(65-70 Lint)
600
$ /INCH
COTTON
4
~50
CORN
10
SORGHUM
6
480
~35
WHEAT
4
200
~27
PEANUTS
6
250
~50
~50
NiTROGEN REQUIREMENTS/INCH
OF IRRIGATION WATER
CORN=10bu/in at 1.0-1.25 #N/bu =10-12#N/Inch
SORGHUM= 8 bu/in at 0.81#N/bu =6-7#N/Inch
COTTON = 65-75# Lint/in at 3-4 #N/100#
=5-7 #N/Inch