Performance of polymer-coated urea (ESN) as a nitrogen source for corn

Larry G. BundyDept. of Soil Science Univ. of Wisconsin

What Is ESN?

• A semi-permeable polymer coating is applied to urea fertilizer.

• The polymer coating controls the rate nitrogen is released to the soil and crop.

• Warming soil temperatures stimulate crop growth and nitrogen release.

• Unreleased nitrogen is protected from exposure to the environment until needed by the crop.

• The protective coating reduces nitrogen loss to the environment.

Recommended Timing of Nitrogen Applications for Corn

Soil Fall PreplantSidedres

sMedium/Fine TextureWell-Drained

OK* Optimum OK

Medium/Fine TexturePoorly Drained

No OK Optimum

Coarse texture No No Optimum

*Includes use of BMPs for fall-applied N.

Timing of Nitrogen Uptake by Corn

0

30

60

90

120

150

180

210

240

Time during growing season

N u

ptak

e, lb

N/a

cre

Apr. May June July Aug. Sept. Oct.

y = 46 + 0.82x - 0.0009x2

R2 = 0.9973

y = 50 + 0.069x + 0.0004x2

R2 = 0.9923

25

50

75

100

125

150

175

200

0 50 100 150 200 250

N rate, lb/acre

Gra

in y

ield

, bu/

acre

Split-Sidedress

Preplant

Effect of N timing on the relationship between N rate and corn grain yield, Hancock 2002.

PROCEDURES

Location: Hancock ARS 2003-2004

Objectives: Determine optimum N rates and time of application for several N fertilizer materials including polymer coated urea (ESN) for corn on sandy irrigated soils

ESN Release Mechanism

0

20

40

60

80

100

0 2 4 6 8 10 12

Time (weeks)

N R

ele

ase

d (

cum

ula

tive

%) Lag period Linear diffusion Decay

H2O H2O

Urea solution concentrationconstant

H2O

Urea solution concentrationdecreases

N Source & timing effects on corn grain yield at Hancock, WI,

2003N rate, lb/acre

N source N timing 150 200 Mean

--- grain yield, bu/acre ---

PCU (ESN) PP 199 208 204a

PP+4 wk 203 206 205a

Am. Sulf. PP 204 190 196ab

PP+DCD 203 200 202ab

4wk & 8 wk 184 204 194abc

4wk w/NI & 8wk 201 216 208a

8 wk 190 190 190bcd

No N control = 107 bu/acre

N Source/timing and N rate effects on corn grain yield at Hancock, WI, 2003

N rate, lb/acre

N source N timing 100 150 200 250 Mean

----- grain yield, bu/acre -----

PCU PP 203 199 208 219 208

PP + 4 wk 183 203 206 198 198

Am. Sulfate 4 wk & 8 wk 175 184 204 189 188

Mean 187b 195ab 206a 202a

No N control = 107 bu/acre

EONR = 188 lb N/acre, Yield @ EONR = 206 bu/acre

EONR = 188 lb/a

Fig. 7. Relationship between N rate and grain yield for three N source/timing treatments, Hancock, WI, 2003. Grain yield values are the average of four replications. EONR, economic optimum N rate.

N rate, lb/acre

0 50 100 150 200 250

Gra

in y

ield

, bu

/acr

e

100

120

140

160

180

200

220

PCU: PPR2 = 0.95 EONR = 200 lb/aPCU: PP + 4 wkR2 = 0.99 EONR = 181 lb/aAS: 4 & 8 wkR2 = 0.98 EONR = 188 lb/a

TREATMENTS -2004• Control (0 lb N/a) + 40 lb S/a*

• Polymer-Coated Urea (ESN) Split (Preplant & 4 wk): 100, 150,

200, and 250 lb N/a + 40 lb S/a. Preplant: 100, 150, 200, and 250

lb N/a + 40 lb S/a.

*S source = gypsum

TREATMENTS - 2004

• Ammonium Sulfate

– Split (4 & 6 wk): 100, 150, 200, and 250 lb N/a.

– Preplant: 150 and 200 lb N/a.

– Preplant + nitrification inhibitor (DCD): 150 and 200 lb N/a

– Sidedress (4 wk): 150 and 200 lb N/a.

TREATMENTS - 2004

• Urea Preplant: 150 and 200 lb N/a. Sidedress (4 wk): 150 and 200

lb N/a + 40 lb S/a. Sidedress (4 wk): 150 and 200

lb N/a w/o S.

OBSERVATIONS -2004

•Rainfall and irrigation patterns

•Visual appearance of 2004 nitrogen treatments

0.00

0.50

1.00

1.50

2.00

2.50

5/1/

04

5/16

/04

5/31

/04

6/15

/04

6/30

/04

7/15

/04

7/30

/04

Precip

Timing of rainfall, irrigation, and N applications. Hancock, WI 2004

Rai

nfal

l (in

ches

)

Date

Preplant NMay 5

4 wk sidedressJune 8

6 wk sidedressJune 22

Total Precip = 17.08”Total Irrig = 6.5”

0.00

0.50

1.00

1.50

2.00

2.50

5/1/

04

5/16

/04

5/31

/04

6/15

/04

6/30

/04

7/15

/04

7/30

/04

Precip

Irrigation

Timing of rainfall, irrigation, and N applications. Hancock, WI 2004

Rai

nfal

l / I

rrig

atio

n (in

ches

)

Date

Preplant NMay 5

4 wk sidedressJune 8

6 wk sidedressJune 22

Total Precip = 17.08”Total Irrig = 6.5”

PCU/ESN, preplant 250 lb N/acre + sulfur

8 July 2004

Ammon. sulf., Split 4 & 6 wk 250 lb N/acre

8 July 2004

Control No N+ Sulfur8 July 2004

Ammonium sulfate, preplant 200 lb N/acre

8 July 2004

Ammonium sulfate, preplant + NI200 lb N/acre

8 July 2004

Urea, preplant + Sulfur200 lb N/acre

8 July 2004

PCU/ESN, preplant 200 lb N/acre + sulfur

8 July 2004

Urea – Sidedress, 4 wk200 lb N/acre + Sulfur

8 July 2004

Urea – Sidedress, 4 wk200 lb N/acre , no Sulfur

8 July 2004

Ammonium sulf.-Sidedress, 4wk 200 lb N/acre

8 July 2004

Ammon. sulf., Split 4 & 6 wk 200 lb N/acre

8 July 2004

PCU/ESN, split, pp & 4 wk200 lb N/acre + sulfur

8 July 2004

SUMMARY - 2004

•Rainfall patterns favored leaching•Preplant N treatments showed N

deficiency (except PCU/ESN)•Sidedress or split N applications

were superior to preplant•PCU/ESN shows potential for

lowering N losses where all or part of the N is applied preplant