Nutrient Considerations with

Corn Stover Harvest

Antonio P. Mallarino

John E. Sawyer

Department of Agronomy

Iowa State University

Stover Harvest for Feed, Bedding, Bioenergy

Much Larger Impacts on K Removal and Soil-Test K than for P

Topics

Corn biomass and carbon

Corn silage harvest and nutrient removal

Corn grain and stover nutrient composition

Corn grain and stover nutrient cost

Stover harvest effect on corn yield and N

fertilization rate in continuous corn

Corn Biomass and Carbon Facts

Grain harvest index is approximately 50%

Half above ground biomass is in grain and

half in vegetation plus cob (stover)

Corn grain has 47.3 lb D.M. per bu

(based on 56 lb/bu at 15.5% moisture)

Carbon concentration (average)

Grain: 43% C (19 lb C/bu equiv.)

Vegetation: 43% C (19 lb C/bu equiv.)

Cob: 45% C (3 lb C/bu equiv.)

Grain ~50%

Silage Harvest

Grain

Leaf Blades

Stalk, Leaf Sheaths

Shank, Husk, Cob Tassel

PMR 1009; Abendroth et al., 2011

Corn Silage Harvest

Silage harvests nearly 100% aboveground

vegetation

Harvest silage at 60-70% moisture

Before plant maturity

Close to total dry matter (DM) accumulation

Close to total nutrient accumulation

Corn Silage Harvest

ISU P and K concentrations in PM 1688

3.5 lb P2O5 per ton silage (65% moisture)

10 lb P2O5 per ton silage (DM basis)

0.5 lb P2O5 per bu equivalent (15% moist.)

9.0 lb K2O per ton silage (65% moisture)

26 lb K2O per ton silage (DM basis)

1.25 lb K2O per bu equivalent

Have not worried about N or other nutrients

removal with silage harvest

Corn Stover Harvest

Grain is harvested separate

Harvest stover after plant maturity and at or

after grain harvest

After total dry matter (DM) accumulation

After total nutrient accumulation

After nutrient leaching loss from plant before

grain harvest or from stover residue

Grain

PMR 1009; Abendroth et al., 2011

Corn Nitrogen Composition – At Maturity

Grain ~70%

Grain

PMR 1009; Abendroth et al., 2011

Corn Phosphorus Composition – At Maturity

Grain ~86%

Grain

PMR 1009; Abendroth et al., 2011

Corn Potassium Composition – At Maturity

Grain ~30%

Corn Stover Harvest Considerations

Consideration of all nutrients removed?

Nutrient removal setting cost of stover?

Estimating amount of stover harvested?

Nutrient removal amount?

Stover moisture?

Corn Nutrient Composition – At Maturity

PM 1688

Gr. St.

16 5.9

13 25 ( 2)

(17)

( 1)

(10)

Nutrient Grain Veg. Cob Grain Veg. Cob

C 3717 3283 469 795 840 787N 110 48 8 24 12 13

P2O5 55 11 -- 12 3 --K2O 37 85 -- 8 22 --

Ca 8 37 -- 2 9 --Mg 9 25 -- 2 6 --S 8 5 -- 2 1 --Zn 0.14 0.12 -- 0.030 0.031 --Mn 0.03 0.27 -- 0.006 0.069 --Cu 0.02 0.06 -- 0.004 0.015 --B 0.04 0.06 -- 0.009 0.015 --Fe 0.22 1.10 -- 0.047 0.281 --

Dry Matter 9355 7816 119214 site years; at plant maturity; 198 bu/acre grain yield.

J. Sawyer and D. Barker, Iowa State University, 2006-2007.

Corn Nutrient Composition

- - - - - lb/acre - - - - - - - - lb/ton (D.M.) - - -

Corn Stover Nutrient Composition

Nutrient Average Range

P2O5 3 10

K2O 19 44

Ca 8 8

Mg 4 7

S 1 1

Zn 0.033 0.052

Mn 0.096 0.167

Cu 0.013 0.024

B 0.010 0.011

Fe 0.148 0.17129 site years, 2008-2011.

Little or no soil contamination.

R. Oltmans and A.P. Mallarino (2011).

Corn Stover at Grain Harvest

- - lb/ton (D.M) - -

Distribution of P Removal in Stover Harvest

from 50 Central Iowa Fields, 2011

Stover P Concentration (lb P2O5/ton)

0 1 2 3 4 5 6 7 8 9 10 11 12

Fre

qu

en

cy (

%)

0

2

4

6

8

10

12

14

16

18

PhosphorusAverage: 3.7Median: 3.3

DM concentrations, M. Darr et al., Iowa State Univ. May contain soil contamination.

Distribution of K Removal in Stover Harvest

from 50 Central Iowa Fields, 2011

DM concentrations, M. Darr et al., Iowa State Univ. May contain soil contamination.

Stover K Concentration (lb K2O/ton)

0 5 10 15 20 25 30 35 40 45

Fre

qu

en

cy (

%)

0

2

4

6

8

10

12

14 PotassiumAverage: 16.5Median: 15.3

Corn Grain Phosphorus and Potassium

Composition Variability

Mallarino et al., 2011 Mallarino et al., 2011

Arrows indicate current ISU Pub. PM-1688 values.

Iowa P-K Recycling Research, 2008 to 2012

Ryan Oltmans and Antonio Mallarino, support by the Iowa Soybean Association and International Plant Nutrition Institute

Corn Stover Phosphorus and Potassium

Concentration Change Over Time

Harvest time currently assumed average

25 lb K2O/ton = 1.0 %

Harvest time currently assumed average

5.9 lb P2O5/ton = 0.13 %

Oltmans and Mallarino, 2011

Data for 9 site-years

Sep Oct Nov Dec Jan Feb Mar Apr May

K C

oncen

tra

tio

n (

lb K

2O

/to

n d

ry m

atte

r)

0

10

20

30

40

50

60

Harvest

On the ground

Black layer Potassium

Sep Oct Nov Dec Jan Feb Mar Apr May

P C

oncen

tra

tio

n (

lb P

2O

5/t

on

dry

ma

tte

r)0

2

4

6

8

10

12

14

16

Harvest

On the ground

Black layerPhosphorus

Partial data set.

Potassium Loss and Precipitation

Oltmans and Mallarino, 2012

Precipitation (inches)

0 5 10 15 20 25

Tis

sue A

ccum

ula

tion (

lb K

2O

/acre

)

0

20

40

60

80

100

120

140

160

Precipitation (inches)

0 5 10 15 20 25

Soybean Corn

Y = 11.1e-(2.93/(X+1.47))

R2 = 0.84

P < 0.01

Y = 23.3e-(5.85/(X+4.70))

R2 = 0.68

P < 0.01

Nutrient Cost in Corn Grain and Stover At Plant Maturity

Nutrient Grain Stover Grain Stover Price Nutrient Product

$/ton $/lb

N 110 54 52.80 25.92 768 0.48 Ammonia

P2O5 55 14 28.05 7.14 645 0.51 DAP

K2O 37 99 18.50 49.50 615 0.50 Potash

Ca 8 41 0.24 1.23 20 0.03 Lime

Mg 9 27 0.27 0.81 20 0.03 Lime

S 8 5 3.36 2.10 750 0.42 Elemental

Total 103.22 86.70

Corn grain at 198 bu/acre; corn stover at 4.5 ton D.M./acre. At plant maturity.

J. Sawyer, Iowa State University.

Example Estimated Nutrient Cost

Fertilizer/Lime

- - lb/acre - - - - $/acre - -

Nutrient Cost in Corn Stover At Grain Harvest

Nutrient Price Nutrient Product

lb/acre $/acre $/ton $/lbP2O5 3 1.53 645 0.51 DAP

K2O 19 9.50 615 0.50 Potash

Ca 8 0.24 20 0.03 Lime

Mg 4 0.12 20 0.03 Lime

S 1 0.42 750 0.42 Elemental

Total 11.81

R.Oltmans and A.P. Mallarino (2011).

Little or no soil contamination.

Per Ton DM

Example Nutrient Cost - Stover at Grain Harvest

Fertilizer/LimeCorn Stover

Corn Stover Equivalent Price to Grain

$/bu $/acre $/lb DM $/ton DM $/lb C $/ton C

5.00 990 0.11 220 0.26 528

6.00 1188 0.13 264 0.32 633

7.00 1386 0.15 308 0.37 739

198 9008 3752

bu/acre lb DM/acre lb C/acre

J. Sawyer, Iowa State University.

Corn Stover Priced Equivalent to Corn Grain

Corn Grain Corn Stover

Stover Removal Impact on Remaining Carbon

No Stover 2 ton Stover DM

Time Period Harvest Harvested

Starting corn stover 3,750 2,110

Remaining after 1 year 1,240 700

Remaining after 4 years 750 420

Remaining after 8 years 560 320

Total lost from soil 3,190 3,430

lb carbon (C)/acre

Theoretical Corn Stover Carbon Remaining in Soil

Assume 33% of stover C remains after one year, 20% of original stover

C remains after four years, 15% of original stover C remains after 8

years; estimates from "Cycles of Soil", 1986, and "Humus Chemistry",

2nd edition, 1994, by F.J. Stevenson.

198 bu/acre grain crop

(4.5 ton DM/acre stover)

Corn Stover Removal and Tillage Effect on

Yield and N Fertilization in Continuous Corn

Residue

Removal EONR YEONR EONR YEONR

lb N/acre bu/acre lb N/acre bu/acre

None 228 179 227 162

50% 203 177 212 173

100% 185 181 189 170

J. Pantoja et al., Iowa State University

Chisel Plow No-Tillage

Effect of tillage and residue removal on corn grain yield

and economic optimum N rate across sites, 2009-2011.

EONR, economic optimum N rate; YEONR, yield at EONR.

EONR and YEONR at 0.10 N:corn grain price ratio.

Corn Stover Removal and Tillage Effect on

Yield and N Fertilization in Continuous Corn

Residue

Removal EONR YEONR EONR YEONR

lb N/acre bu/acre lb N/acre bu/acre

None 181 205 161 164

Partial 161 215 140 154

Full 161 215 102 137

Three sites normal precip., one site low precip.

J.A. Coulter and E.D. Nafziger, 2008.

Effect of tillage and residue removal on corn grain yield

and economic optimum N rate, 2006-2007, Univ. IL.

Avg. across systems No-till (Low precip)

EONR, economic optimum N rate; YEONR, yield at EONR.

EONR and YEONR at 0.10 N:corn grain price ratio.

Summary

In Iowa continuous corn research (short

term)

Stover harvest reduced the EONR by 20 lb

N/acre (half removal) and 40 lb N/acre (full

removal)

Stover harvest did not change yield with

chisel plow

Stover harvest increased yield with no-tillage

(6%)

Summary

Corn stover has less N than grain (2x less)

Corn stover has less P than grain (4x less)

Corn stover has more K than grain (3x more)

Stover nutrient concentration varies

Stover harvest in addition to grain harvest

removes more nutrients than grain alone

Stover harvest removes carbon

Summary

Nutrient value in harvested stover depends

on harvest amount, timing, and fertilizer price

Suggested average corn stover nutrient

concentrations (lb/ton dry matter)

But remember the variation (conc. and soil)

N: 17 lb/ton

P2O5: 3 lb/ton

K2O: 19 lb/ton

Test harvested stover for nutrient content