TIMING, FERTILITY AND AGRONOMICS OF IRRIGATED CORN AND SOYBEAN Angela McClure Extension Corn and Soybeans Plant Sciences

We Irrigate to Provide more Consistent Yields 300

134

12

41

39

57

250 200 dryland Irrigated

150 100 50 2008

2009

2010

2011

4 yr ave

Irrigated and dryland corn yields, UT Milan Pioneer 33N58 with 220 units N (slide format courtesy of Pioneer)

Just Adding Water Doesn’t Fix a Field or “Why Don’t I Make a Lot More Corn or Beans with irrigation?” Started too late or quit too early ■ Not enough N fertilizer, or P, K or micronutrients ■ Population not right for hybrid/variety planted ■ Poor drainage in some areas of field ■ Compaction ■ Need to find the right balance for field ■

Corn Water Needs Kernel Row number (V9-V12)

1.75”

Ear length (V12-V17)

2.0”

Ear Size Potential (V17-R2)

2.3”

Grain fill (R3- black layer)

varies

0.4

R1= silking R2= blister

0.3

R3

0.2

R4

0.1

R5 R6

0

WATER USE (INCHES)

Critical Water Need

Approx. Inch/Week

2

6

10

14

POL MLK

Source: University of Florida.

DO

FD

BL

Estimated Water Use of Corn during Various Stages of Growth Days After Planting

Growth Stage

Inches per Day

Total Water Use (inches)

0-20

seedling

.06

1.2

20-30

5"-10"

.09

.9

30-40

10"-20"

.15

1.5

40-50

20"-50"

.20

2.0

50-60

50"-80“

.21

2.1

60-70

80"-silking

.25

2.5

70-100

silking-grainfill

.33

10.0

100-110

grainfill

.25

2.5

110-120

maturity

.23

2.3

0-120 Slide courtesy of Pioneer

25.0

Terminate Irrigation at Black Layer • “Milk Line”- hard

starch starts forming at Early Dent • Progression of milk-line

indicates the maturity of kernels • ~20 days for line to go from top to base of kernel • Line ½ way down kernel means about another 10 days to black layer • Shutting water off too early can reduce yields 10 to 25%)

Corn Planting Date and Yield (Non-irrigated productive vs variable corn fields; Milan, REC; Dekalb 63-84)

Irrigated Corn Seeding Suggestions (E. Larson, Mississippi State University)

Seeding Rate

Seed Spacing (inches)

Final Stand

20” rows

30” rows

38” rows

5% loss

26000

12.1

8.0

6.3

24700

23400

28000

11.2

7.5

5.9

26600

25200

30000

10.5

7.0

5.5

28500

27000

32000

9.8

6.5

5.4

30400

28800

34000

9.2

6.1

4.9

32300

30600

36000

8.7

5.8

4.6

34200

32400

40000+

??

??

??

42000

38000

10% loss

Best for: Optimum Planting Dates

Current UT Nitrogen Recommendations for Corn Expected Grain Yield

Lbs N per bushel of grain

100-125 bushels

Nitrogen (lbs/acre) 120

125-150 bushels

150

1.2- 1.00

150-175 bushels

180

1.2- 1.03

175-200 bushels

210

1.2- 1.05

200-225 bushels

240

1.2- 1.07

1.2- 0.96

Nitrogen Response in Corn (4 yr data; corn/soy rotation, UTMilan REC) 300 250

Irrigated Non Irrigated

200 150 100 50

0 0 lbs

55 lbs

110 lbs

165 lbs

220 lbs

275 lbs

Increasing UAN Efficiency with Placement  Inject or spray behind coulter  Surface band followed by irrigation  Fertigation

Increasing Urea Efficiency • Placement– Irrigate into soil within 24 hrs – 0.2” water to move into top 1” soil – 1.2” water to move into top 6” of soil

• Timing– Split apply fertilizer >120 lbs – Pre-tassel applications may have value when large amounts are applied during the season

Lake County, TN Urea Stabilizer Demo (75-0-0 at planting; 20-0-0 pre tassel; irrig w/in 24 hrs)

2008 data

Fertigation – Application of fertilizer via irrigation water.

Example N plan : 200 bu/acre irrigated corn Expected yield goal 200 bu/acre resulting in 210 lb. N recommendation 35 lbs. at planting 135 lbs. as sidedress 40 lbs 2 week prior to tassel (aerial) 50 lbs. at planting 160 lbs. as sidedress V3-V5 corn 50 lbs. at planting 80 lbs. sidedress or fertigation, knee high 50 lbs. fertigation, waist high 30 lbs. fertigation, 2 week prior to tassel

Fertigation Calibration Calculate the total volume of fertilizer need for the actual area to be irrigated. • Deduct for dry areas / corners

Example: • 11 acres – 1 dry acre = 10 acres • a 30 lb.of N/ acre application will require 300 lb. total N. • Given that 1 gal. of 28% N contain 3.1 lb. of actual N • 300 / 3.1 = 97 gal. of 28%

UT Phosphate and Potash Recommendations …monitor levels closely with irrigation Soil Level High

P205 lb/A Corn Soybean 0 0

K20 lb/A Corn Soybean 0 0

Medium

50-90

20

50-90

40

100-180

40

100-180

80

Low

Irrigation Scheduling in Soybean General Soybean Growth and Water Use • Soybeans need 20-24

inches water per season • About 2 bu/A for every inch of water used • 65% of water is used during reproductive stages

Crop Development

Germination, Seedling

Water Use (in/day)

0.05-0.10 (typically not recommended

Rapid veg. Growth

0.10-0.20

Flowering to R3 R4-R6

0.20 0.25-0.30

R7 to harvest

0.05-0.20 (typically not recommended)

Days after Planting to Reach “R” Stage (Non-irrigated Indeterminate Soybeans, UT Milan) Maturity Group

R1

R2

R3

R4

R5

R6

R7

R8

Harvest Date

(Days after Planting to reach stage) 3.9

31 d

41 d

49 d

65 d

75 d

90 d

102 d 113 d

120 d

4.2

31 d

41 d

49 d

75 d

80 d

97 d

109 d 123 d

129 d

4.6

26 d

49 d

56 d

75 d

84 d

102 d 113 d 123 d

129 d

4.7

41 d

44 d

56 d

69 d

84 d

102 d 113 d 123 d

129 d

4.8

46 d

53 d

65 d

75 d

87 d

105 d 109 d 126 d

129 d

5.0

41 d

53 d

65 d

75 d

90 d

105 d 116 d 130 d

134 d

Planted May 20, 2011; average over 130K and 180K populations

Timing Irrigation in Soybean • When to Start? • Beginning bloom (traditional); Beginning pod (??) • Get full effect when watered throughout reproductive

period for maximum seed number and weight Stage

Time to Stage

Maturity Group

R1 (early bloom)

6-7 weeks after planting

Indeterminate (April planted)

4-5 weeks after planting

Indeterminate (May Planted)

10-12 weeks after planting

Determinate (May planted)

Terminating Irrigation in Soybean When to Stop?? • Moist soil at R6 (full seed) • Rule of Thumb: at least 50% of pods have green seed touching within the pod (Univ. of AR)

Stage Interval R1-R6

Time from R1-R6 60 days

Indeterminate Maturity Group* 3.9

67 days

4.2

60 days

4.7

59 days

4.8

64 days

5.0

* UT data non-irrigated MG planted May 20, 2011

R5= beginning seed (3mm size)

R6= full seed (green seed touching)

***Located on at least one of the 4 top

fully developed leaf nodes

Soybean Seed Recs for Irrigation • Narrow rows canopy quicker but no yield

advantage (Miss State data) • Plant at 125K to 160K to achieve final stand of 100K to 120K regardless of row spacing • Don’t plant at high seeding rates – beans compensate for thinner stands by setting more pods; less potential to lodge at reduced planting rates!! • Irrigate double crop beans to get beans out of the ground or increase plant height/canopy

UT Phosphate and Potash recommendations …monitor levels closely with irrigation Soil Level High

P205 (lb/A) Corn Soybean 0 0

K20 (lb/A) Corn Soybean 0 0

Medium

50-90

20

50-90

40

100-180

40

100-180

80

Low

Weed control Under Irrigation Weeds love water! • Good soil moisture season-long can cause some weeds to emerge throughout season • Consider narrow rows soybeans to improve canopy closure • Requires PRE (residual) + post with residual in both corn and soybean

Preemergence Applications have an Impact Roundup PowerMax on Palmer 1 - 3” and 5 - 7”

Envive 3 oz/A Pre

Palmer amaranth control

Stand reduction (% of control) Norsworthy 2009

A

A

A A A B B

A A B

A B

B C C

A A A B B

Using irrigation to get the most from Questions??? pesticides Timely application of irrigation water : • Improves incorporation of herbicides. • Improves activation of herbicides. • Improves activation / reactivation of insecticides.