University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Publications from USDA-ARS / UNL Faculty
USDA Agricultural Research Service --Lincoln,
Nebraska
1-1-2010
Nutrient Removal as a Function of Corn Stover
Cutting Height and Cob Harvest
Jane M. F. Johnson
USDA-Agricultural Research Service, [email protected]
Wally W. Wilhelm
USDA-Agricultural Research Service
Douglas L. Karlen
USDA-Agricultural Research Service, [email protected]
David W. Archer
USDA-Agricultural Research Service, [email protected]
Brian J. Wienhold
University of Nebraska - Lincoln, [email protected]
See next page for additional authors
Follow this and additional works at: http://digitalcommons.unl.edu/usdaarsfacpub
Johnson, Jane M. F.; Wilhelm, Wally W.; Karlen, Douglas L.; Archer, David W.; Wienhold, Brian J.; Lightle, David T.; Laird, David;
Baker, John; Ochsner, Tyson E.; Novak, Jeff M.; Halvorson, Ardell D.; Arriaga, Francisco; and Barbour, Nancy, "Nutrient Removal as a
Function of Corn Stover Cutting Height and Cob Harvest" (2010). Publications from USDA-ARS / UNL Faculty. Paper 1190.
http://digitalcommons.unl.edu/usdaarsfacpub/1190
This Article is brought to you for free and open access by the USDA Agricultural Research Service --Lincoln, Nebraska at DigitalCommons@University
of Nebraska - Lincoln. It has been accepted for inclusion in Publications from USDA-ARS / UNL Faculty by an authorized administrator of
DigitalCommons@University of Nebraska - Lincoln.
Authors
Jane M. F. Johnson, Wally W. Wilhelm, Douglas L. Karlen, David W. Archer, Brian J. Wienhold, David T.
Lightle, David Laird, John Baker, Tyson E. Ochsner, Jeff M. Novak, Ardell D. Halvorson, Francisco Arriaga,
and Nancy Barbour
This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/usdaarsfacpub/1190
Bioenerg. Res. (2010) 3:342–352
DOI 10.1007/s12155-010-9093-3
Nutrient Removal as a Function of Corn Stover Cutting
Height and Cob Harvest
Jane M. F. Johnson & Wally W. Wilhelm & Douglas L. Karlen & David W. Archer &
Brian Wienhold & David T. Lightle & David Laird & John Baker & Tyson E. Ochsner &
Jeff M. Novak & Ardell D. Halvorson & Francisco Arriaga & Nancy Barbour
Published online: 15 April 2010
# US Government 2010
This article is a U.S. government work, and is not subject to copyright in the United States.
Abstract One-pass harvest equipment has been developed to
collect corn (Zea mays L.) grain, stover, and cobs that can be
used as bioenergy feedstock. Nutrients removed in these
feedstocks have soil fertility implication and affect feedstock
quality. The study objectives were to quantify nutrient
concentrations and potential removal as a function of cutting
height, plant organ, and physiological stage. Plant samples
were collected in 10-cm increments at seven diverse
geographic locations at two maturities and analyzed for
multiple elements. At grain harvest, nutrient concentration
averaged 5.5 gN kg−1, 0.5 gP kg−1, and 6.2 gK kg−1 in cobs,
7.5 gN kg−1, 1.2 gP kg−1, and 8.7 gK kg−1 in the above-ear
stover fraction, and 6.4 gN kg−1, 1.0 gP kg−1, and 10.7 g
K kg−1 in the below-ear stover fraction (stover fractions
exclude cobs). The average collective cost to replace N, P,
and K was $11.66 Mg−1 for cobs, $17.59 Mg−1 for above-ear
Wally W. Wilhelm deceased.
The US Department of Agriculture offers its programs to all eligible
persons regardless of race, color, age, sex, or national origin and is an
equal opportunity employer.
The use of trade, firm, or corporation names in this publication is for
the information and convenience of the reader. Such use does not
constitute an official endorsement or approval by the US Department
of Agriculture or the Agricultural Research Service of any product or
service to the exclusion of others that may be suitable.
Electronic supplementary material The online version of this article
(doi:10.1007/s12155-010-9093-3) contains supplementary material,
which is available to authorized users.
J. M. F. Johnson (*) : N. Barbour
North Central Soil Conservation Research Laboratory,
USDA-Agricultural Research Service,
803 Iowa Ave.,
Morris, MN 56267, USA
e-mail: [email protected]
D. L. Karlen : D. Laird
National Laboratory for Agriculture and the Environment,
USDA-Agricultural Research Service,
2110 University Boulevard,
Ames, IA 50011, USA
N. Barbour
e-mail: [email protected]
D. L. Karlen
e-mail: [email protected]
W. W. Wilhelm : B. Wienhold
Agroecosystems Management Research Unit,
USDA-Agricultural Research Service,
279 Plant Science, UNL,
Lincoln, NE 68583, USA
D. Laird
e-mail: [email protected]
B. Wienhold
e-mail: [email protected]
D. W. Archer
Northern Great Plains Research Laboratory,
USDA-Agricultural Research Service,
PO Box 459, Mandan, ND 58554, USA
e-mail: [email protected]
Bioenerg. Res. (2010) 3:342–352
stover, and $18.11 Mg−1 for below-ear stover. If 3 Mg ha−1
of above-ear stover fraction plus 1 Mg of cobs are harvested,
an average N, P, and K replacement cost was estimated at
$64 ha−1. Collecting cobs or above-ear stover fraction may
provide a higher quality feedstock while removing fewer
nutrients compared to whole stover removal. This information will enable producers to balance soil fertility by
adjusting fertilizer rates and to sustain soil quality by
predicting C removal for different harvest scenarios. It also
provides elemental information to the bioenergy industry.
343
An estimated 218 million Mg of dry feedstock per year will
be needed to meet the 76 billion liters of second-generation
(non-food source) renewable fuels target for 2022 in the
USA [8]. Multiple, regionally specific lignocellulosic
materials will be used to achieve this goal, but one of the
most important in Midwestern USA will be corn (Zea mays
L.) stover. Other potential feedstock materials include other
crop residues such as wheat (Triticum aestivum L.),
dedicated annual and perennial energy crops (e.g., switchgrass (Panicum virgatum L.), sorghum (Sorghum bicolor
L.), miscanthus (Miscanthus), or sugarcane (Saccharum
officinarum L.) bagasse)), and woody species such as
poplar (Poplar ssp.) and pine (Pinus ssp.) [8]. Additional
feedstock biomass will be needed to meet demands for
producing biopower [6] and bioproducts [29].
Corn stover refers to the aboveground, non-grain plant
parts including the cob, leaves, and stalk. Currently, stover
is collected primarily using several field operations following corn grain harvest, in which the stover is cut,
windrowed, baled, and hauled to a storage site [33]. These
operations increase the number trips across the field, often
during a time of year when rainfall or snowfall can limit
harvest time and create soil conditions that are susceptible
to compaction. To reduce the number of field operations
and cost of feedstock collection, one-pass harvest equipment that can collect corn grain as well as stover and/or
cobs is being developed [34] but is not yet commercially
available. Initial one-pass harvest studies have been conducted to assess various harvest scenarios for collecting
corn stover and cobs [18, 34]. A study in Iowa concluded
that harvesting grain and stover in one-pass with a 40-cm
cutting height could save time and fuel and provide higher
quality feedstock for ethanol fermentation than a multi-pass
baling operation [18]. Another study suggested feedstock
fractionation could reduce ethanol production costs by
minimizing pretreatment and hydrolysis requirements [10].
For example, husk and cobs released more glucan and
produced more ethanol compared to stalk bottoms when
using the same pretreatment and hydrolysis treatment
D. T. Lightle
USDA-NRCS National Soil Survey Center,
100 Centennial Mall N., Rm 152,
Lincoln, NE 68508-3866, USA
e-mail: [email protected]
A. D. Halvorson
USDA-Agricultural Research Service,
2150 Centre Ave., Bldg. D. Suite 100,
Fort Collins, CO 80526, USA
e-mail: [email protected]
Keywords Corn cobs . Corn stover . Plant nutrition .
Soil fertility . Biofuel feedstock
Abbreviations
BON
Bonferroni minimum significant difference
GLM
General linear model
ICP-OES
Inductively coupled plasma-optical emission
spectroscopy
LSD
Least significant difference
MDL
Minimum detection limit
SOC
Soil organic carbon
Introduction
J. Baker : T. E. Ochsner
Soil and Water Management Research Unit,
USDA-Agricultural Research Service,
439 Borlaug Hall, 1991 Upper Buford Circle,
St. Paul, MN 55108, USA
J. Baker
e-mail: [email protected]
T. E. Ochsner
e-mail: [email protected]
J. M. Novak
Coastal Plains Research Center,
USDA-Agricultural Research Service,
2611 W. Lucas St.,
Florence, SC 29501, USA
e-mail: [email protected]
F. Arriaga
National Soil Dynamics Research Laboratory,
USDA-Agricultural Research Service,
411 S. Donahue Dr.,
Auburn, AL 36832, USA
e-mail: [email protected]
Present Address:
T. E. Ochsner
Department of Plant and Soil Sciences,
Oklahoma State University,
Stillwater, OK 74078, USA
344
even though the stalk contained a comparable amount of
glucan [10].
With successful development of one-pass technology for
stover harvest, the next critical question is at what height the
corn plant should be cut. This is critical because the amount of
crop residue that can be harvested in a sustainable manner
without degrading soil resources through loss of soil organic
carbon (SOC) or erosion varies by location, crop rotation, and
tillage practice [26, 38, 39]. The amount of residue that needs
to be returned to the field to maintain SOC can exceed that
needed to control wind or water erosion [39]. Furthermore,
harvesting crop residues removes more mineral nutrients
than harvesting only grain [10, 17, 18, 24, 25]. Developing a
broad comprehensive dataset on nutrient removal is important because the amounts removed will depend on element
concentration, quantity, and type of stover harvested and
frequency of removal.
Nutrient concentrations in corn stover vary between upper
and lower portions of the stalk [10, 18, 23]. Therefore, cutting
height during harvest will impact both average nutrient
concentration in the harvested biomass and the quantity of
nutrient removed from the field. Nutrient concentrations in
cobs may differ from those in stalks [10] because of
differences among plant organs. Unfortunately, there are
few publications with multiple locations that provide both
information on nutrient concentration in harvested biomass
and that also differentiate the vertical distribution of nutrients
and differences among stover fractions [10, 20]. Literature
from animal science focuses on the feed quality of plant
material and frequently is based on material collected at
physiological maturity or younger [4, 7, 22, 28]. We collected
plants both at physiological maturity and at grain harvest to
compare nutrient concentration between the two dates. If
there is little difference in nutrient concentration, it suggests
data from the animal science literature can be directly used
for estimating nutrient removal at grain harvest in the stover.
Weather conditions may sometimes force producers to
harvest at earlier than desired times. Although corn stover
can have high moisture content at earlier harvest dates, wet
storage by ensilage is a possible method to store high
moisture bioenergy feedstock [33]. Ensiling corn stover can
improve harvest timeliness and reduce harvest losses [33],
but does not necessarily provide an economic advantage
compared to dry storage methods (e.g., bales) [2]. Thus,
several locations included more than one plant maturity.
Developing a broad, geographic database with vertical
distribution of nutrients has at least three practical applications. First, the quantity of C that is removed not only
affects the value of the biomass crop but also the amount of
biomass returned to the soil, which functions as food for
microorganisms, maintaining soil structure and SOC.
Second, inorganic elements such as K, Cl, and Si can
negatively affect feedstock quality for both biochemical
Bioenerg. Res. (2010) 3:342–352
conversion and thermochemical processing [3]. Third,
removal of essential plant nutrients with biomass harvest
will affect the amount and type of fertilizer that is required
to maintain soil fertility. The replacement value of the
nutrients removed with the stover will have a large impact
on the fair market value for the feedstock.
Recognizing the applications listed above and other
needs associated with the developing biofuel and bioproducts industries, this multi-location project builds on a
companion publication quantifying the vertical distribution
of corn stover as a function of cutting height, geographic
location, and plant maturity [40]. Our specific objectives for
this study were to quantify nutrient concentrations and
potential nutrient removal as a function of vertical cutting
height, plant organ, and physiological growth stage at
different geographic locations and for hybrids with varying
maturities. The impetus for this study was use of stover as a
bioenergy feedstock, but it would be applicable regardless
of the reason for stover collection and removal (e.g., for
fodder, bedding, or as a biomaterial for construction
materials).
Materials and Methods
Experimental Sites
A multi-location experiment was conducted at Ames, IA,
USA; Auburn, AL, USA; Fort Collins, CO, USA; Florence,
SC, USA; Lincoln, NE, USA; Mandan, ND, USA; Morris,
MN, USA; and St. Paul, MN, USA. Each location had at
least one site and sampling date, although some had
multiple sites, management practices, and/or sampling dates
(Table 1). Collectively, these locations represent a wide
range of climatic, soil, hybrid, planting date, population
densities, and cultural practices [40] associated with corn
production throughout the USA.
Sampling Method
Plants were destructively sampled from a 1.0-m2 area at
physiological maturity and/or at grain harvest. The corn
plants were cut as close to the soil surface as possible. Ears
were removed from the husk and dried separately. The height
to the base of the grain-containing ear (ear height), height to
the node at which the ear shank was attached to the stalk
(shank height), and plant height were recorded to the nearest
centimeter for each plant. Corn stalks were marked at 10-cm
intervals starting at ground level and continuing upward with
the top segment being one 10-cm interval above the base of
the primary grain-containing ear. All plant material above the
top interval was pooled into a single above-ear sample. All
plant parts (cob, above-ear, and 10-cm increment samples)
Waukegan silt loam
Barnes clay loam
Temvik-Wilton silt loam
Aksarben silty clay loam
Fort Collins clay loam
Norfolk sandy loam
Decatur silt loam
Pacolet fine sandy loam
Clarion loam
Cannisteo silty clay loam
Coland clay loam
Soil and series
M-Sy
M-Sy
Sf
cM
Irrigated, cM
M-C, winter legumes,
irrigate
M-C, winter cereal
rye cover
M-Sy
M-Sy since 2002
cM since 2004
M-Sy
Rotation
C Cotton, cM continuous maize, M maize, NS not sampled, Sf sunflower, Sy soybean
The field or treatment refers to parent experiment from which plants were collected
St. Paul, MN
Morris, MN
Mandan, ND
Lincoln, NE
Fort Collins, CO
Florence, SC
Swan Lake Research
Farm
Rosemount
Boyd farm
Bruner
Biochar applied
No biochar
Old Cotton Rotation
Site
Tennessee Valley
Research Station
Conventional
Conservation
Conventional
No tillage
Disk
No tillage
85 days
79 days
Ames, IA
Auburn, AL
Field or treatment
Location
Chisel-plow
Chisel-plow
Paraplow /disk
Paraplow
Plow
No tillage
Disk
No tillage
No tillage
Disk
Spring Paraplow
Chisel/disk
Chisel/disk
Chisel-plow
Tillage
Table 1 Ancillary and descriptive data for the eight locations across the USA included in the study
Cropland 296TS MF-B7;
92 days
Dekalb DKC 50-20; 100 days
Legend LR9385RR; 85 days
Legend LR9779RR; 77 days
DeKalb 61-69; 110 days
Dekalb 69-72 RR;
119 days
Pioneer 31D61 YGCB;
120 days
DK 69-72 (RR2) AF2;
119 days
Pioneer 39B77BtLL; 88 days
Pioneer 34A20; 109 days
Agrigold 6395; 109 days
Pioneer 34A20; 109 days
Hybrid; relative maturity
74,000
77,780
62,700
79,000
92,220
54,320
92,860
93,860
74,000
74,000
74,000
Plant ha−1
Plant density
9 Sep
11 Sep
26 Sep
24 Sep
12 Sep
11 Sep
NS
NS
NS
6 Sep
13 Sep
NS
Physiological
maturity
1 Oct
28 Sep
29 Oct
29 Oct
11 Oct
23 Oct
10 Sep
20 Sep
19 Sep
NS
NS
5 Oct
Grain
harvest
Sampling date, 2007
Bioenerg. Res. (2010) 3:342–352
345
346
Bioenerg. Res. (2010) 3:342–352
were oven-dried at 60°C to a constant weight. Grain was
removed from cob prior to determining dry cob weight.
Our rationale for this sampling approach was to mimic a
one-pass harvest system that could collect grain and cobs, or
grain and stover. A high-cut (18) one-pass treatment would at
least collect everything at and above the ear, while a low cut
treatment would collect everything above a stubble height of
10 cm. The 10-cm sampling increments were to help
interpolate between the low- and high-cut treatments.
Segment samples from multiple plants (within a replication
at each site) were pooled to provide sufficient plant material for
chemical analysis. Typically, segments were combined from
five to ten plants, depending on plant population (Table 1). C
and N analyses for all locations were conducted at the ARSAgroecosystems Research Unit in Lincoln, NE, USA. All the
Cl, microwave digestion, and inductively coupled plasmaoptical emission spectroscopy (ICP-OES) analyses were done
at the ARS-North Central Soil Conservation Research
Laboratory in Morris, MN, USA. Total C and total N in the
plant tissue were determined by combustion (900°C) with a
Carlo Erba combustion analyzer (Thermo Scientific, Waltham, MA, USA). Chloride was extracted by shaking in
0.01 M CaSO4, and the Cl concentration was determined by
flow injection analysis using the mercury (II) thiocyanate
colorimetric method measured on a Technicon AutoAnalyzer
II (ALPKEM, Clackamas, OR, USA) at 480 nm with a
minimum detection limit (MDL) of 1 µg mL−1 [13, 35]. All
other nutrients were determined by ICP-OES on a Varian
Vista-Pro CCD simultaneous ICP-OES (Varian Incorp., Palo
Alto, CA, USA) following a concentrated HNO3 acid
microwave digestion procedure using a Mars Xpress Microwave Digester (CEM Corp., Mathews, NC, USA) based on
USEPA 3051 and USEPA 3051A methods and manufac-
turer's recommendations [37]. Elements of interest as plant
nutrient or as fouling agents had the following MDL in
µg mL−1: 0.4, Al; 0.0.007, B; 0.006, Ca; 0.006, Cu; 0.012,
Fe; 0.129, K; 0.003, Mg; 0.001, Mn; 0.13, P; 0.175, S; 0.028,
Si; and 0.06, Zn, based on HNO3 acid background matrix
following the manufacturer's recommendation for this ICOOES instrument.
Statistical Analysis
This study was designed to primarily provide information on
the vertical distribution of nutrient concentrations from plants
harvested at physiological maturity and/or just prior to
combine harvest at several locations throughout the USA.
The study was not designed to delineate causal relationships
or to examine differences associated with location, soil
resource, management practices, and/or hybrid selection.
The multi-location intent was to include a range of hybrids,
relative maturities, and climatic conditions, thus providing a
general survey of how nutrient concentration varied vertically
within corn plants at or approximately 3 weeks after
physiological maturity.
A general linear model using SAS software, version 9.1
(SAS Institute, Gary, NC, USA) [32] was used to determine if
there were statistically significant differences in nutrient
concentration. Stover fraction or segments were treated as
random variables, and variability due to location and
location-specific factors (e.g., management practice and
hybrid) was included in the error term. Mean comparisons
of nutrient concentration among three stover fractions (i.e.,
above-ear without cob, below-ear, and cob) were made using
a protected least significant difference (LSD; p≤0.05) [32].
The number of cob observations was used to calculate
Table 2 Average concentration of several plant elements (g kg−1) based on all fields and treatments within and across locations for above ear
(without cob), below ear, and cob
Physiological maturity
N
Grain harvest
Above ear (gkg−1) Below ear (gkg−1) Cob (gkg−1) LSDa (gkg−1) Above ear (gkg−1) Below ear (gkg−1) Cob (gkg−1) LSD (gkg−1)
18
18
12
26
26
20
C
N
P
428
7.44
0.80
435
5.48
0.62
450
4.35
0.40
7.26
1.36
0.42
433
7.45
1.24
428
6.41
1.01
450
5.46
0.50
7.23
0.79
0.44
K
S
Ca
Cl
Si
10.84
0.61
4.17
3.03
1.17
12.17
0.41
2.99
4.17
0.93
5.35
0.15
ND
1.73
0.19
4.77
0.20
0.59
1.68
0.25
8.66
0.62
2.96
1.99
0.98
10.71
0.51
3.51
2.57
0.86
6.25
0.28
ND
2.19
0.19
2.44
0.11
0.49
1.10
0.30
Some locations were only sampled at one maturity date (Table 1); also, some locations did not save cobs for analysis
LSD least significant difference, ND not detected
a
LSD (p≤0.05) to compare among segments within a maturity, calculated using the number of cob observations
Bioenerg. Res. (2010) 3:342–352
347
Table 3 Comparison of element concentration in the above-ear corn stover fraction at two sampling dates, using data only from locations that
sampled at both physiological maturity and grain harvest, n=12
C (gkg−1)
N (gkg−1)
P (gkg−1)
K (gkg−1)
S (gkg−1)
Ca (gkg−1)
Cl (gkg−1)
Si (gkg−1)
Physiological maturity
Grain harvest
425
432
8.16
6.77
0.75
0.71
12.2
8.4
0.72
0.53
4.33
2.91
2.59
1.86
1.16
1.13
Significance
–**
–*
NS
NS
–*
–***
NS
NS
NS not significant at p≤0.05
*Significant at 0.05 probability level
**Significant at 0.01 probability level
***Significant at 0.001 probability level
protected LSDs, which are a conservative approach as there
were fewer cob observations than stover observations.
Differences among nutrient concentrations in the 10-cm
segments below the ear were compared using Bonferroni
minimum significant difference (p≤0.05), as there were
more than six means [32].
A subset of five locations that was sampled from the same
fields and treatments at both physiological and grain harvest
was used to determine if nutrient concentration changed
between the two sample dates. Cob data was not available
from two of the locations. General linear model analysis was
run separately for the three stover fractions. Sample time was
treated as a random variable, and variability due to location
and location-specific factors (e.g., management and hybrid)
was included in the error term. Significant differences are
reported at p≤0.05.
Additional descriptive statistics (arithmetic means, standard errors, and number of observations) were calculated
within locations for all elements for the three corn stover
fractions at both sample dates (Supplemental Tables 1–4).
At Fort Collins, multiple plants were harvested, but there
was only one replication for each maturity, so a standard
error for the Fort Collins location was not calculated. At
Mandan, there were two replications for each maturity, but
plant materials from each replication were insufficient for
analysis, so materials from the two replications were
pooled. At other sites, there were at least two sampling
areas or replications. Standard errors were reported as an
indicator of variability.
Fig. 1 Concentrations of C, N,
P, K, and Cl assigned to the
midpoint of each 10-cm segment
below the ear collected at grain
harvest. Lines are error bars;
number of locations and replication is not constant with
height. Note that the x-axis
scales vary among nutrients.
Error bar at the bottom of the
graph represents Bonferroni
minimum significant difference
(p≤0.05) among segment nutrient concentrations within a maturity, when general linear
model indicated significance
among segments
8
12
0.4
0.8
1.2
5
10
15
20
2
8
12
0.4
0.8
1.2
5
10
15
20
2
120
420
440
460
4
420
440
460
4
Results
Stover Fraction Nutrient Concentrations
Stover nutrient concentrations above and below the ear and
within the cobs were determined at all locations for at least
one and sometimes two sampling dates. At physiological
maturity (Table 2), cobs had lower N, K, S, Ca, Cl, and Si
concentrations but higher C content than the stover
4
6
8
4
6
8
100
Plant height
(cm)
Plant height
(cm)
80
60
40
20
0
BON
C g kg-1
N g kg-1
P g kg-1
K g kg-1
Cl g kg-1
Bioenerg. Res. (2010) 3:342–352
120
Plant height
(cm)
Fig. 2 Concentration of Ca,
Mg, S, Si, and Fe assigned to
the midpoint of each 10-cm
segment below the ear collected
at grain harvest. Lines are error
bars; number of locations and
replication is not constant with
height. Note that the x-axis
scales vary among nutrients.
Error bar at the bottom of the
graph represents Bonferroni
minimum significant difference
(p≤0.05) among segment nutrient concentrations when general
linear model indicated significance among segments
0
2
4
6 0
2
4
6
0.4
0.8
1.2 0.0
0.2
0.4
0.0
0.4
0.8
1.2
120
100
100
80
80
60
60
40
40
20
20
0
0
Plant height
(cm)
348
BON
2
4
6 0
Ca g kg-1
2
4
fractions. At grain harvest, the P concentration was also
significantly lower in cobs compared to either stover
fraction. At both sampling dates, the concentration of Ca
in cobs was below the MDL. The concentration of N, S,
and Ca in the above-ear stover fraction exceeded that below
the ear at physiological maturity. At grain harvest, the
above-ear stover fraction had 16% higher N and 21%
higher S concentrations than the below-ear stover fraction.
The concentration of C, N, P, K, S, Ca, Cl, and Si in
cobs or in the below-ear stover fraction did not change
Plant height
(cm)
120
0
150
300
450 0
30
60
90 0
6
0.4
Mg g kg-1
30
0.8
1.2 0.0
S g kg-1
0.2
0.4
0.0
Fe g kg-1
0.4
0.8
1.2
Si g kg-1
significantly between the two sample dates (data not
shown). The concentration did decrease 17% for N, 26%
for S, and 32% for Ca between physiological maturity and
grain harvest in the above-ear stover fraction (Table 3). The
concentration of N, S, and Ca were greater in the above-ear
stover compared to the below-ear fraction, while P
concentration did differ significantly between the two
fractions (Table 2), such that losing above-ear stover would
result in harvesting a greater portion of material with lower
concentrations of N, S, and Ca.
60
90
0
3
6
9
0
3
6
9
120
100
100
80
80
60
60
40
40
20
20
0
0
Plant height
(cm)
0
BON
0
150
300
450 0
Al mg kg-1
30
60
Mn mg kg-1
90 0
30
60
90
Zn mg kg-1
Fig. 3 Concentration of Al, Mn, Zn, B, and Cu assigned to the
midpoint of each 10-cm segment below the ear collected at grain
harvest. Lines are error bars; number of locations and replication is
not constant with height. Note that the x-axis scales vary among
0
3
6
B mg kg-1
9
0
3
6
9
Cu mg kg-1
nutrients. Error bar at the bottom of graph represents Bonferroni
minimum significant difference (p≤0.05) among segment nutrient
concentrations when general linear model indicated significance
among segments
Bioenerg. Res. (2010) 3:342–352
349
Harvested
Remaining
Amount of C
-1
Mg ha
0
2
4
Cutting Height
(cm)
140
0
30
60
90
C
Amount of nutrient
kg ha-1
0
10
20
K
30 0
3
6
Mg
9
140
P
120
120
100
100
80
80
60
60
40
40
20
20
0
140
N
Ca
Cl
0
140
S
120
120
100
100
80
80
60
60
40
40
20
20
0
Cutting Height
(cm)
Fig. 4 The amount of C
(Mg ha−1) or nutrient (kg ha−1)
that would be harvested (solid
symbols) or remain in the field
(open symbols), with biomass
harvest at successive 10-cm interval. Any material on the
ground was assumed to always
remain in the field. These data
assume that cobs would be
harvested
0
0
30
60
90
0
10
20
30 0
10
20
30 0
3
6
9
Amount of nutrient
kg ha-1
Vertical Distribution of Nutrient Below the Ear
differences in the vertical distribution of any of the other
nutrients (Figs. 1, 2, and 3).
Comparisons among the 10-cm increment segments
collected below the ear were made within a sampling
date, as not all locations were able to sample on both
dates. Because the difference between sample's dates was
not significant in the below-ear stover fraction (data not
shown), only the vertical distribution at grain harvest is
presented (Figs. 1, 2, and 3). The concentration of N
tended to increase in the segments approaching the ear
compared to those near the soil (Fig. 1). Fe (Fig. 2) and Al
(Fig. 3) had higher concentrations in the bottom 10 cm,
which may reflect some soil contamination, despite efforts
to avoid such contamination. There were no significant
Table 4 Average cost to replace N, P, K, and total fertilizer cost per
Mg feedstock removed, using nutrient concentration at grain harvest
in Table 2 at and 5-year average cost (2005–2009), average cost
Stover fraction
N
P
$ Mg−1 feedstock
K
Above ear (excluding cob)
Below ear
Cob
5.80
4.99
4.25
8.34
10.32
6.02
3.45
2.81
1.39
Discussion
Nutrient Removal and Soil Fertility
Consistent with previous studies [10, 12, 16, 18, 23],
nutrient concentrations in this study differed among stover
fractions, cutting heights, and plant maturity when sampled
(Tables 2 and 3, Figs. 1, 2, and 3). This is important
because the amount of N, S, and Ca removed at grain
harvest could easily be overestimated if based on concen-
supplying N, P, and K as anhydrous ammonia ($0.78 kg−1),
superphosphate ($2.78 kg−1), and muriate of potash ($0.96 kg−1),
respectively [27]
N, P, and K value
$ Mg−1 feedstock
Harvest rate
Mgha−1
N, P, and K cost
$ ha−1
17.59
18.11
11.66
3
2
1
52.76
36.23
11.66
Hypothetical harvest rate and corresponding cost provided as an example and does not represent a recommended or average rate
350
trations measured at physiological maturity instead of grain
harvest, especially if a portion of the plant from above the
ear is removed (Table 3). The amount of an element
removed from or retained in the field is a function of
concentration and biomass harvested (Fig. 4). As the
cutting height is lowered, the amount of C and nutrients
harvested and removed from the field is increased, and
proportionally less is returned to the field. The optimum
cutting height depends upon the selection criteria. If the
goal is maximum stover harvest, then the lowest cutting
height is best. Collection costs per unit of biomass tend to
decline at higher removal rates and higher yields [14].
However, if maintaining soil organic C, soil fertility, and
preventing erosion are of primary importance, then harvesting only the cob or upper portions of the stalk and cob may
be more appropriate (Tables 2 and 3) [15, 40].
It is straightforward to measure nutrient concentration
and determine the amount of nutrient removed by harvesting corn stover. However, impacts on soil fertility are more
challenging to predict and depend upon the specific
nutrient, soil type, spatial variability, and parent material,
climate, and crop rotation. Stover has a high C to N ratio
(Table 2), and over the short-term, net N-immobilization is
expected to occur [36]. As decomposition of the residue
progresses, net mineralization should occur [19, 30, 36].
Repeated harvest of crop residue has been demonstrated to
reduce N mineralization [21, 31] and decrease betaglucosaminidiase activity, which is an indicator of N
mineralization [11]. Studies in Ohio and in Minnesota both
reported that harvesting corn stover can result in less soil
organic N than returning stover to the field [5, 9].
Soil fertility is influenced by numerous factors including
residue amount, type, and placement interacting with soil
temperature, moisture, texture, and fertilizer application [1,
20]. For example, 25 years of stover harvest in New York
on a Raynham silt loam significantly reduced soil K and
Mg, but only the reduction in K levels was of agronomic
consequence [26]. In the same study, repeated stover
harvest did not significantly decrease soil concentrations
of N, P, Ca, Fe, Mn, Zn, and Al. Another study, which was
located in Ohio, showed that 4 years of stover removal
reduced available P, K, Mg, and Ca on silty clay loam soils
but had very little impact on nutrient availability on clay
loam soils [5]. In general, residue removal has the potential
to reduce soil fertility levels. The extent of fertility
reduction is soil and climate dependent; therefore, producers will need to utilize soil tests and crop scouting to
avoid unexpected nutrient deficiencies.
Nutrient Content and Feedstock Quality
The cutting height or fraction harvested impacts feedstock
quality for both thermochemical and fermentation platforms.
Bioenerg. Res. (2010) 3:342–352
Cobs have lower concentrations of several nutrients (N, P, K,
S, and Ca) compared to stover fractions (Table 2). Therefore,
they would remove fewer plant nutrients. Low concentrations of N and S in the feedstock reduces the potential for
SOx and NOx in the flue gases [41] during thermochemical
processing, which must be scrubbed from flue gases. Raising
the cutting height from 20 to 70 cm during a one-pass
operation reduces the mass of C, N, P, and S harvested about
20% and reduces the amount of Cl by 22%, K by 25%, and
Mg and Ca by 29% (Fig. 4). Raising the cutting height
disproportionately reduces the amount of elements that are
undesirable (Ca, Mg, and K; Fig. 4) in the feedstock relative
to the amount of C, which is directly proportional to biomass
[40]. Fermentation relies on sugar (or converting cellulose to
sugars) to produce liquid fuels like ethanol. Other researchers [10] reported that the amount of recoverable sugars in the
stover above the ear exceeded that below the ear, even
though the sugar content between the two segments was
comparable. The results by Duguid et al. [10] suggest the
stover above the ear is a higher quality fermentation
feedstock. The lower portion of the stock will be wetter
and more likely to have soil contamination [18]. All these
factors suggest that the upper portion of the corn stover
provides a higher quality feedstock than the lower portion
for both thermochemical and fermentation platforms.
Economic Considerations
Nutrient replacement costs were calculated based on 5-year
(2005–2009) average prices of $0.64 kg−1 for anhydrous
ammonia, $0.55 kg−1 for superphosphate, and $0.49 kg−1 for
potash, which corresponds to $0.78 kg−1 elemental N,
$2.75 kg−1 elemental P, and $0.96 kg−1 elemental K,
respectively [27]. Based on the average N, P, and K
concentrations at grain harvest (Table 2) and assuming a
cob harvest rate of 1 Mg ha−1, the corresponding removal
rate would average 4.5 kg N, 0.3 kg P, and 7.2 kg K per
hectare. At these prices and concentration, replacing these
macronutrients would cost $11.66 ha−1 (Table 4). The
amount of biomass and nutrient removal is a function of
cutting height when corn is harvested with a one-pass
system. The highest cutting height made with a one-pass
system likely would be just below the ear. For the purpose of
illustration, assume that a one-pass system at grain harvest
collected 3 Mg ha−1 above-ear stover fraction harvested plus
1 Mg of cobs. Based on the cob and above-ear nutrient
concentrations, 27.8 kg N, 4.22 kg P, and 32.2 kg K (Table 2)
per hectare may be harvested at a corresponding replacement
cost of about $64 ha−1 (Table 4). As the harvest rate and or
nutrient concentration increases, the cost of nutrient replacement also increases. For example, if an additional 2 Mg ha−1
was harvested of the material below the ear in addition to the
cobs and the above-ear stover fraction, the amount of N, P,
Bioenerg. Res. (2010) 3:342–352
and K removed could exceed $100 ha−1 (Table 4). Calculation of the minimum payment necessary for biomass
harvest to be profitable would need to include nutrient
replacement costs: harvest, transportation, and storage costs,
as well as any impacts on future crop productivity.
We presented detailed information on the vertical distribution of C and mineral elements in corncobs and stover. This
information allows for an estimation of the amount of nutrients
removed during stover or cob harvest. It also provides
information on the concentration of elements that negatively
impact feedstock quality. Harvesting only cobs or cutting just
below the ear improves the feedstock quality and reduces the
impact of nutrient removal. Because of the relationship
between residue removal and its nutrient content, producers
harvesting cobs and or stover are advised to utilize soil tests
and monitor crops for signs of nutrient deficiency and modify
their fertilizer management accordingly. Short- and long-term
fertility risks, together with the risks of erosion and loss of
SOC, must be considered in making the decisions concerning
residue harvest including if, what, and how often to harvest.
Acknowledgements The authors dedicate this publication to Dr.
Wally Wilhelm. We thank B. Burmeister for proofreading, but we take
full responsibility for any errors. We also thank the reviewers and Dr.
Michael Casler for insightful and constructive suggestions for
improvements. We acknowledge the efforts of technical and student
helpers for sampling and processing plant tissue samples. This work
contributes to the USDA-Agricultural Research Service, crosslocation–Renewable Energy Assessment Project (REAP). Publication
costs were covered by funding from the North Central Regional Sun
Grant Center at South Dakota State University through a grant
provided by the US Department of Energy Office of Biomass
Programs under award number DE-FC36-05GO85041.
References
1. Andraski TW, Bundy LG (2008) Corn residue and nitrogen source
effects on nitrogen availability in no-till corn. Agron J 100:1274–1279
2. Aristos A, Schechinger T, Birrell SJ, Euken J (2007) Collection,
commercial processing, and utilization of corn stover. Final technical
report. DOE scientific and technical information. Available via http://
www.osti.gov/bridge/product.biblio.jsp?osti_id=917000. doi:10.2172/
917000. Cited 29 Jan 2010
3. Arvelakis S, Koukios EG (2002) Physicochemical upgrading of
agroresidues as feedstocks for energy production via thermochemical conversion methods. Biomass Bioe 22:331–348
4. Bernard JK, West JW, Trammell DS, Cross GH (2004) Influence
of corn variety and cutting height on nutritive value of silage fed
to lactating dairy cows. J Dairy Sci 87:2172–2176
5. Blanco-Canqui H, Lal R (2009) Corn stover removal for expanded
uses reduces soil fertility and structural stability. Soil Sci Soc Am
J 73:418–426
6. Campbell JE, Lobell DB, Field CB (2009) Greater transportation
energy and GHG offsets from bioelectricity than ethanol. Science
324:1055–1057
7. Cummins DG (1970) Quality and yield of corn plants and
component parts when harvested for silage at different maturity
stages. Agron J 62:781–784
351
8. Biomass Research and Development Board (2008) Increasing
feedstock production for biofuels: economic drivers, environmental implications, and the role of research. Biomass Research and
Development Board. Available via http://www.brdisolutions.com/
Site%20Docs/Increasing%20Feedstock_revised.pdf. Cited 8 Dec
2008
9. Dolan MS, Clapp CE, Allmaras RR, Baker JM, Molina JAE (2006)
Soil organic carbon and nitrogen in a Minnesota soil as related to
tillage, residue and nitrogen management. Soil Tillage Res 89:221–231
10. Duguid KB, Montross MD, Radtke CW, Crofcheck CL, Wendt
LM, Shearer SA (2009) Effect of anatomical fractionation on the
enzymatic hydrolysis of acid and alkaline pretreated corn stover.
Bioresour Technol 100:5189–5195
11. Ekenler M, Tabatabai MA (2002) Beta-glucosaminidase activity
of soils: effect of cropping systems and its relationship to nitrogen
mineralization. Biol Fertil Soils 36:367–376
12. Fageria NK (2004) Dry matter yield and shoot nutrient concentrations of upland rice, common bean, corn, and soybean grown in
rotation on an Oxisol. Commun Soil Sci Plant Anal 35:961–974
13. Gavlak RG, Horneck DA, Miller RO (1994) Soil and plant tissue
reference methods for the Western region. Western regional
publication. WREP 125. University of Alaska, Fairbanks
14. Graham RL, Nelson R, Sheehan J, Perlack RD, Wright LL (2007)
Current and potential U.S. corn stover supplies. Agron J 99:1–11
15. Halvorson AD, Johnson JMF (2009) Corn cob characteristics in
irrigated central Great Plains studies. Agron J 101:390–399
16. Hanway JJ (1962) Corn growth and composition in relation to soil
fertility: I. Growth of different plant parts and relation between
leaf weight and grain yield. Agron J 54:145–148
17. Heggenstaller AH, Anex RP, Liebman M, Sundberg DN, Gibson
LR (2008) Productivity and nutrient dynamics in bioenergy
double-cropping systems. Agron J 100:1740–1748
18. Hoskinson RL, Karlen DL, Birrell SJ, Radtke CW, Wilhelm WW
(2007) Engineering, nutrient removal, and feedstock conversion
evaluations of four corn stover harvest scenarios. Biomass Bioe
31:126–136
19. Johnson JMF, Barbour NW, Weyers SL (2007) Chemical
composition of crop biomass impacts its decomposition. Soil Sci
Soc Am J 71:155–162
20. Johnson JMF, Papiernik SK, Mikha MM, Spokas K, Tomer MD,
Weyers SL (2009) Soil processes and residue harvest management.
In: Lal R, Steward B (eds) Carbon management, fuels, and soil
quality. Taylor and Francis, LLC, New York, pp 1–44
21. Kapkiyai JJ, Karanja NK, Qureshi JN, Smithson PC, Woomer PL
(1999) Soil organic matter and nutrient dynamics in a Kenyan
Nitisol under long-term fertilizer and organic input management.
Soil Bio Biochem 31:1773–1782
22. Kung L Jr, Moulder BM, Mulrooney CM, Teller RS, Schmidt RJ
(2008) The effect of silage cutting height on the nutritive value of
a normal corn silage hybrid compared with brown midrib corn
silage fed to lactating cows. J Dairy Sci 91:1451–1457
23. Lewis AL, Cox WJ, Cherney JH (2004) Hybrid, maturity, and
cutting height interactions on corn forage yield and quality. Agron
J 96:267–274
24. Li BY, Zhou DM, Cang L, Zhang HL, Fan XH, Qin SW (2007)
Soil micronutrient availability to crops as affected by long-term
inorganic and organic fertilizer applications. Soil Tillage Res
96:166–173
25. Lindstrom MJ, Gupta SC, Onstad CA, Holt RF, Larson WE
(1981) Crop residue removal and tillage—effects of soil erosion
and nutrient loss in the Corn Belt. US Department of Agriculture,
Ag Info. Bull. No. 442
26. Moebius-Clune BN, Van Es HM, Idowu OJ, Schindelbeck RR,
Moebius-Clune DJ, Wolfe DW et al (2008) Long-term effects of
harvesting maize stover and tillage on soil quality. Soil Sci Soc
Am J 72:960–969
352
27. NASS (2009) Quick stats. USDA National Agricultural Statistic
Service, Washington, Available via http://www.nass.usda.gov/.
Cited 10 Feb 2010
28. Neylon JM, Kung L Jr (2003) Effects of cutting height and
maturity on the nutritive value of corn silage for lactating cows. J
Dairy Sci 86:2163–2169
29. Ng TK, Busche RM, McDonald CC, Hardy RWF (1983)
Production of feedstock chemicals. Science 219:733–740
30. Paul EA, Clark FE (1996) Soil microbiology and biochemistry.
Academic, San Diego
31. Salinas-Garcia JR, Baez-Gonzalez AD, Tiscareno-Lopez M,
Rosales-Robles E (2001) Residue removal and tillage interaction
effects on soil properties under rain-fed corn production in central
Mexico. Soil Tillage Res 59:67–79
32. SAS (2002) SAS version 9.1. SAS Institute Inc, Cary
33. Shinners KJ, Binversie BN, Muck RE, Weimer PJ (2007)
Comparison of wet and dry corn stover harvest and storage.
Biomass Bioe 31:211–221
34. Shinners KJ, Boettcher GC, Hoffman DS, Munk JT, Muck RE,
Weimer PJ (2009) Single-pass harvest of corn grain and stover:
performance of three harvester configurations. Trans ASABE 52:51–60
Bioenerg. Res. (2010) 3:342–352
35. Technicon (1973) Technicon industrial method AA. ii no. 99-70
w. Sept. 1973. Chloride in water and waste water. Technicon
Instrument Corporation, Tarrytown
36. Tisdall JM, Nelson WL, Beaton JD (1986) Soil fertility and
fertilizers. Macmillan Publishing Company, New York
37. US-EPA (2007) Method 3051a: microwave assisted acid digestion
of sediments, sludges, soils, and oils Available via http://www.
epa.gov/epawaste/hazard/testmethods/sw846/pdfs/3051a.pdf. Cited 22 Oct 2008
38. Wilhelm WW, Johnson JMF, Hatfield JL, Voorhees WB, Linden
DR (2004) Crop and soil productivity response to corn residue
removal: a literature review. Agron J 96:1–17
39. Wilhelm WW, Johnson JMF, Karlen DL, Lightle DT (2007) Corn
stover to sustain soil organic carbon further constrains biomass
supply. Agron J 99:1665–1667
40. Wilhelm WW, Johnson JMF, Lightle D, Barbour NW, Karlen
DL, Laird DA et al (2010) Vertical distribution of corn stover
dry mass grown at several U.S. locations. BioEnergy Res (in
press)
41. Yu F, Ruan R, Steele P (2008) Consecutive reaction model for the
pyrolysis of corn cob. Trans ASABE 51:1023–1028
Nutrient removal as function of corn stover cutting height and cob harvest: Supplemental data
Jane M. F. Johnson, Wally W. Wilhelm (deceased), Douglas L. Karlen, David W. Archer, Brian Wienhold, David T. Lightle,
David Laird, John Baker, Tyson E. Ochsner, Jeff M. Novak, Ardell D. Halvorson, Francisco Arriaga, Nancy Barbour
Supplemental Table 1. Concentration of plant C and macronutrients (g kg -1) in the stover fraction above the ear (excluding
cob), below the ear, and in the cob at physiological maturity of plants collected at several locations. Some locations
collected plants from multiple sites, hybrids or tillages. Values are means with standard error in parenthesis.
Location
n
Stover
fraction
Ames, IA - Boyd
Lincoln, NE, disk
3
3
3
3
3
3
1
1
1
1
1
1
2
2
Lincoln, NE, - no
tillage
2
2
Mandan, ND 85 day
1
1
1
1
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Ames, IA Bruner
Fort Collins, CO conventional
Fort Collins, CO no tillage
Mandan, ND - 79
C
N
P
K
Ca
Mg
S
-------------------------------------------------------------------g kg-1 --------------------------------------------------------------------------------438 (7.7)
5.17 (0.58)
0.53 (0.06)
5.89 (0.36)
4.06 (0.10)
3.22 (0.14)
0.37 (0.02)
444 (6.3)
3.33 (0.06)
0.29 (0.02)
5.08 (0.43)
2.33 (0.05)
2.29 (0.09)
0.16 (0.02)
447 (13)
4.70 (0.70)
0.28 (0.01)
3.95 (0.20)
NDa
0.26 (0.02)
0.04 (0.00)
430 (5.0)
6.85 (0.30)
1.13 (0.43)
10.19 (0.56)
3.65 (0.18)
1.75 (0.31)
0.40 (0.04)
438 (4.3)
4.22 (0.31)
1.34 (0.96)
11.03 (3.76)
3.62 (0.50)
2.21 (0.43)
0.26 (0.01)
453 (1.7)
4.27 (0.40)
0.59 (0.97)
6.61 (0.08)
ND
0.14 (0.01)
0.10 (0.09)
420 (NC)
4.65 (NC)
0.34 (NC)
20.13 (NC)
4.80 (NC)
2.68 (NC)
1.19 (NC)
430 (NC)
6.97 (NC)
0.29 (NC)
20.10 (NC)
3.57 (NC)
3.03 (NC)
1.28 (NC)
454 (NC)
4.65 (NC)
0.39 (NC)
7.85 (NC)
ND
0.29 (NC)
0.26 (NC)
430 (NC)
7.11 (NC)
0.48 (NC)
20.79 (NC)
2.81 (NC)
1.87 (NC)
0.57 (NC)
432 (NC)
8.09 (NC)
0.39 (NC)
22.61 (NC)
2.46 (NC)
2.50 (NC)
0.64 (NC)
452 (NC)
4.74 (NC)
0.40 (NC)
5.90 (NC)
ND
0.30 (NC)
0.20 (NC)
427 (1.3)
8.29 (0.84)
1.11 (0.02)
15.17 (0.78)
3.36 (0.91)
0.94 (0.17)
0.54 (63)
433 (1.0)
6.79 (0.69)
0.76 (0.09)
18.19 (2.09)
2.32 (0.09)
1.23 (0.01)
0.45 (20)
NA
NA
NA
NA
NA
NA
NA
421 (3.2)
8.39 (0.19)
1.29 (0.09)
16.06 (1.31)
3.87 (0.908)
0.92 (0.1)
0.67 (34)
434 (1.2)
10.92 (NC)
0.80 (0.14)
22.23 (0.34)
2.23 (0.20)
0.98 (0.02)
0.43 (24)
NA
NA
NA
NA
NA
NA
NA
427 (NC)
10.92 (NC)
0.92 (NC)
10.15 (NC)
4.66 (NC)
4.74 (NC)
0.92(NC)
428 (NC)
7.47 (NC)
0.54 (NC)
10.22 (NC)
3.48 (NC)
4.71 (NC)
0.55 (NC)
451 (NC)
5.31 (NC)
0.76 (NC)
4.03 (NC)
ND
0.98 (NC)
0.64 (NC)
420 (NC)
9.94 (NC)
0.83 (NC)
13.25 (NC)
4.34 (NC)
4.75 (NC)
1.01 (NC)
1
Location
n
Stover
fraction
C
N
P
K
Ca
Mg
S
-------------------------------------------------------------------g kg-1 --------------------------------------------------------------------------------day
1
Below ear 416 (NC)
6.99 (NC)
0.45 (NC)
17.91 (NC)
2.80 (NC)
4.14 (NC)
0.54 (NC)
1
Cob
455 (NC)
3.35 (NC)
0.29 (NC)
4.31 (NC)
ND
0.52 (NC)
0.24 (NC)
Morris, MN
2
Above ear 424 (2.9)
5.85 (0.21)
0.32 (0.03)
2.95 (0.13)
4.42 (0.38)
6.25 (0.72)
0.71 (0.13)
2
Below ear 439 (1.2)
4.09 (0.76)
0.22 (0.04)
2.68 (0.28)
3.75 (0.23)
4.30 (0.14)
0.47 (0.11)
2
Cob
446 (1.4)
7.47 (1.48)
0.17 (0.13)
5.24 (0.40)
ND
0.25 (0.02)
0.11 (0.02)
St. Paul, MN
2
Above ear 429 (6.9)
8.77 (1.90)
0.74 (0.13)
7.10 (1.70)
5.98 (0.52)
4.00 (0.22)
0.58 (0.13)
2
Below ear 436 (7.1)
7.47 (1.48)
0.48 (0.04)
6.85 (1.11)
3.55 (0.68)
3.44 (0.45)
0.34 (0.06)
Cob
NA
NA
NA
NA
NA
NA
NA
Overall Location
10 Above ear 426 (1.8)
7.86 (0.56)
0.77 (0.11)
12.17 (1.89)
4.19 (0.28)
3.11 (0.57)
0.70 (0.08)
Average
10 Below ear 433 (2.4)
6.03 (0.54)
0.56 (0.11)
13.69 (2.34)
3.01 (0.20)
2.88 (0.40)
0.51 (0.10)
7
Cob
451 (1.3)
4.38 (0.26)
0.41 (0.08)
5.41 (0.56)
ND
0.39 (0.11)
0.23 (0.08)
LSDb
5.7
0.84
0.25
2.38
0.39
0.53
0.10
aabbreviations: LSD, Least significant difference; NA, Not available; NC, not calculated insufficient number of replications to calculated standard error; ND, not
detected
b LSD for among overall average of segments.
2
Supplemental Table 2. Concentration of plant C and macronutrients (g kg-1) in the stover fraction above the ear
(excluding cob), below the ear, and in the cob at grain harvest of plants collected at several locations. Some locations
collected plants from multiple sites, hybrids or tillages. Values are means with standard error in parenthesis.
Location
Ames, IA - char
Ames, IA - no
biochar
Florence, SC conservation
Florence, SC conventional
Fort Collins, CO conventional
Fort Collins, CO
- no tillage
Lincoln, NE disk
Lincoln, NE - no
Tillage
Mandan, ND 85 day
N
Stover
fraction
4
4
4
4
4
4
3
3
3
3
3
3
1
1
1
1
1
1
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
2
2 Below ear
Cob
2 Above ear
2 Below ear
Cob
1 Above ear
1 Below ear
1 Cob
C
N
P
K
Ca
Mg
S
-------------------------------------------------------------------g kg-1 ----------------------------------------------------------------------------------421 (3.7)
8.78 (0.18)
2.13 (0.13)
7.87 (0.36)
3.47 (0.28)
2.32 (0.24)
0.81 (0.06)
414 (2.0)
5.93 (0.20)
1.54 (0.17)
9.34 (0.90)
4.29 (0.28)
2.40 (0.16)
0.55 (0.03)
444 (1.9)
6.76 (0.12)
0.58 (0.08)
4.18 (0.64)
0.002 (0.002)
0.32 (0.05)
0.49 (0.04)
421 (3.1)
9.38 (0.21)
2.54 (0.18)
7.89 (0.47)
3.81 (0.12)
2.49 (0.18)
0.84 (0.05)
409 (1.2)
6.56 (0.40)
1.73 (0.15)
8.66 (0.90)
4.71 (0.13)
2.43 (0.21)
0.57(0.03)
443 (3.6)
6.32 (0.16)
0.58 (0.02)
4.08 (0.23)
NDa
0.37 (0.02)
0.36 (0.11)
450 (2.5)
5.18 (0.01)
1.07 (0.30)
9.27 (1.63)
2.18 (0.23)
2.44 (0.40)
0.52 (0.03)
444 (2.0)
7.09 (0.74)
1.70 (0.67)
9.54 (2.72)
3.50 (0.38)
3.86 (0.54)
0.51 (0.05)
457 (1.2)
5.18 (0.57)
0.77 (0.14)
6.98 (0.97)
ND
0.25 (0.01)
0.20 (0.04)
451 (3.7)
5.83 (0.38)
0.46 (0.03)
11.1 (1.61)
2.11 (0.18)
1.59(0.11)
0.47 (0.05)
433 (1.4)
6.75 (1.06)
0.46 (0.05)
13.7 (0.57)
3.47 (0.40)
2.48 (0.16)
0.43 (0.01)
455 (2.3)
4.82 (0.17)
0.49 (0.07)
9.58 (1.55)
ND
0.17 (0.02)
0.18 (0.04)
438 (NC)
5.04 (NC)
0.18 (NC)
15.2 (NC)
2.05 (NC)
1.421 (NC)
0.56 (NC)
441 (NC)
6.61 (NC)
0.30 (NC)
16.5 (NC)
2.74 (NC)
2.88 (NC)
1.15 (NC)
453 (NC)
4.62 (NC)
0.23 (NC)
9.55 (NC)
ND
0.138 (NC)
0.18 (NC)
434 (NC)
5.37 (NC)
0.28 (NC)
15.6 (NC)
2.56 (NC)
1.653 (NC)
0.47 (NC)
439 (NC)
8.06 (NC)
0.29 (NC)
19.3 (NC)
2.23 (NC)
2.562 (NC)
0.68 (NC)
454 (NC)
4.28 (NC)
0.36 (NC)
9.05 (NC)
ND
0.278 (NC)
0.18 (NC)
429 (3.2)
8.06 (0.09)
1.52 (0.41)
9.60 (0.93)
2.79 (0.14)
1.16 (0.02)
0.54 (0.05)
430 (2.8)
NA
432 (5.4)
440 (0.9)
NA
422 (NC)
419 (NC)
445 (NC)
7.34 (0.78)
NA
6.85 (0.81)
5.84 (0.67)
NA
7.70 (NC)
7.41 (NC)
6.04 (NC)
1.13 (0.35)
NA
1.10 (0.51)
0.76 (0.27)
NA
1.08 (NC)
0.69 (NC)
0.32 (NC)
13.4 (2.47)
NA
10.9 (0.78)
17.5 (1.72)
NA
7.37 (NC)
14.1 (NC)
4.23 (NC)
2.39 (0.14)
NA
2.56 (0.29)
2.11 (0.07)
NA
3.60 (NC)
3.01 (NC)
ND
1.48 (0.14)
NA
0.83 (0.15)
1.02 (0.04)
NA
4.18 (NC)
4.59 (NC)
0.75 (NC)
0.41 (0.02)
NA
0.47 (0.05)
0.38 (0.01)
NA
0.99 (NC)
0.63 (NC)
0.30 (NC)
3
Location
N
Stover
fraction
C
N
P
K
Ca
Mg
S
-------------------------------------------------------------------g kg-1 ----------------------------------------------------------------------------------Mandan, ND 1 Above ear
424 (NC)
8.19 (NC)
0.48 (NC)
9.28 (NC)
2.58 (NC)
2.83 (NC)
0.61 (NC)
79 day
1 Below ear
424 (NC)
6.04 (NC)
0.31 (NC)
13.45 (NC)
2.50 (NC)
4.09 (NC)
0.46 (NC)
1 Cob
470 (NC)
4.66 (NC)
0.27 (NC)
7.40 (NC)
ND
0.38 (NC)
0.04 (NC)
Morris, MN
2 Above ear
431 (2.3)
5.34 (0.52)
0.28 (0.06)
2.25 (0.04)
2.64 (0.48)
2.94 (0.67)
0.39 (0.01)
2 Below ear
435 (3.6)
4.19 (0.17)
0.21 (0.01)
2.62 (0.13)
3.04 (0.4)
2.87 (0.50)
0.24 (0.03)
2 Cob
447 (2.8)
4.53 (0.83)
0.20 (0.01)
6.01 (1.30)
ND
0.30 (0.07)
0.17 (0.06)
St. Paul, MN
2 Above ear
438 (0.1)
7.22 (0.87)
0.59 (0.13)
3.99 (0.06)
4.08 (0.03)
3.10 (0.34)
0.54 (0.08)
2 Below ear
439 (1.3)
6.67 (0.02)
0.46 (0.01)
3.31 (0.00)
4.19 (0.31)
3.32 (0.43)
0.41 (0.00)
Cob
NA
NA
NA
NA
NA
NA
NA
Overall average
12 Above ear
433 (3.0)
7.10 (0.41)
0.98 (0.22)
9.19 (1.12)
2.87 (0.20)
2.25 (0.28)
0.60 (0.05)
12 Below ear
431 (3.3)
6.44 (0.25)
0.80 (0.17)
11.8 (1.51)
3.18 (0.25)
2.83 (0.30)
0.54 (0.07)
9 Cob
452 (2.8)
5.04 (0.30)
0.42 (0.06)
6.78 (0.77)
0.0002 (0.00)
0.33 (0.06)
0.23 (0.04)
LSDb
4.0
0.58
0.27
1.29
0.33
0.25
0.08
aabbreviations: LSD, Least significant difference; NA, Not available; NC, not calculated insufficient number of replications to calculated standard error; ND, not
detected
b LSD for among overall average of segments.
4
Supplemental Table 3. Concentrations of elements in mg kg-1 (B, Cu, Fe, Mn, Zn, Al), or g kg-1 (Cl, Si) in the stover
fraction above the ear (excluding cob), below the ear, and in the cob at physiological maturity of plants collected at several
locations. Some locations collected plants from multiple sites, hybrids or tillages. Values are means with standard error in
parenthesis.
Location
Ames, IA - Boyd
n
Stover
fraction
Lincoln, NE disk
3
3
3
3
3
3
1
1
1
1
1
1
2
2
Lincoln, NE - no
tillage
2
2
Mandan, ND 85 day
1
1
1
1
1
1
2
2
2
2
Ames, IA Bruner
Fort Collins, CO
- conventional
Fort Collins, CO
- no tillage
Mandan, ND 79 day
Morris, MN
St. Paul, MN
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
B
Cu
Fe
Mn
Zn
Al
-------------------------------------------------mg kg-1----------------------------------------------------4.7 (0.5)
3.0 (0.5)
41.9 (1.5)
31.1 (4.4)
3.0 (3.0)
9.9 (1.5)
2.6 (0.1)
0.8 (0.2)
202 (31)
24.1 (1.7)
2.7 (2.7)
139 (19.6)
0.0 (0.0)
1.2 (1.2)
8.75 (2.9)
2.36 (0.8)
16.4 (8.7)
5.3 (0.0)
5.2 (0.4)
4.3 (0.5)
43.6 (3.9)
17.3 (0.8)
1.1 (1.1)
10.5 (2.9)
3.6 (0.3)
2.6 (0.1)
98.8 (7.3)
20.6 (0.8)
19.4 (5.0)
57.2 (12.3)
0.6 (0.1)
1.8 (0.9)
9.15 (1.0)
0.85 (0.4)
61.9 (49.9)
NDa
16.6 (NC)
10.1 (NC)
96.2 (NC)
65.6 (NC)
ND
53.6 (NC)
7.2 (NC)
4.6 (NC)
118 (NC)
40.7 (NC)
ND
90.6 (NC)
1.6 (NC)
6.5 (NC)
187 (NC)
5.85 (NC)
ND
52.3 (NC)
11.7 (NC)
12.8 (NC)
70.5 (NC)
45.0 (NC)
ND
29.3 (NC)
5.4 (NC)
3.3 (NC)
89.6 (NC)
27.4 (NC)
ND
80.0 (NC)
1.9 (NC)
5.9 (NC)
121 (NC)
5.82 (NC)
ND
33.8 (NC)
6.0 (0.5)
5.1 (0.3)
47.6 (8.5)
33.4 (6.5)
5.3 (5.3)
9.4 (1.6)
4.5 (0.2)
2.5 (0.4)
135 (40.3)
24.9 (1.8)
ND
87.9 (36.8)
NA
NA
NA
NA
NA
NA
6.7 (0.6)
4.8 (0.0)
53.7 (8.1)
31.1 (0.3)
0.5 (0.5)
42.9 (27.9)
4.9 (0.3)
1.5 (0.3)
81.5 (5.2)
20.6 (2.0)
ND
53.8 (11.0)
NA
NA
NA
NA
NA
NA
11.6 (NC)
6.7 (NC)
89.0 (NC)
97.2 (NC)
39.9 ()
29.5 (NC)
5.0 (NC)
3.8 (NC)
405 (NC)
60.9 (NC)
52.2 ()
284 (NC)
0.9 (NC)
3.4 (NC)
11.4 (NC)
14.5 (NC)
ND
ND
14.1 (NC)
11.0 (NC)
75.5 (NC)
109.3 (NC)
ND
73.0 (NC)
5.7 (NC)
4.2 (NC)
375 (NC)
64.8 (NC)
52.6 ()
246 (NC)
1.1 (NC)
0.5 (NC)
9.01 (NC)
7.59 (NC)
31.8 ()
ND
8.5 (0.7)
5.9 (0.5)
58.3 (2.9)
54.3 (9.7)
30.1 (26.4)
43.1 (11.5)
5.2 (0.6)
2.9 (0.1)
259 (64.0)
51.3 (4.4)
97.8 (67.1)
173 (28.6)
1.4 (0.5)
ND
87.3 (68.1)
5.05 (0.01)
ND
ND
5.3 (0.9)
6.4 (0.3)
76.0 (16.8)
79.9 (41.6)
ND
19.9 (8.7)
Cl
Si
------------- g kg-1 ------------3.11 (0.13) 1.00 (0.03)
5.15 (0.25) 0.78 (0.06)
1.26 (0.12) 0.14 (0.01)
4.73 (0.08) 1.39 (0.23)
6.12 (0.53) 1.36 (0.04)
2.29 (0.11) 0.14 (0.00)
3.67 (NC)
2.02 (NC)
8.42 (NC)
1.66 (NC)
2.51 (NC)
0.34 (NC)
4.38 (NC)
1.56 (NC)
7.22 (NC)
1.27 (NC)
2.66 (NC)
0.33 (NC)
5.22(1.19) 1.05 (0.02)
5.56 (0.05) 0.64 (0.01)
NA
NA
4.15 (0.75) 0.96 (0.12)
ND 0.61 (0.14)
NA
NA
0.15 (NC)
0.99 (NC)
0.11 (NC)
0.74 (NC)
0.62 (NC)
0.29 (NC)
1.02 (NC)
1.48 (NC)
1.20 (NC)
1.06 (NC)
1.13 (NC)
0.21 (NC)
1.5 (0.06) 0.89 (0.06)
1.4 (0.06) 0.83 (0.02)
1.57 (0.04) 0.11 (0.01)
0.05 (0.05) 1.06 (0.16)
5
2 Below ear
2.9 (0.1)
2.8 (0.2)
287 (96.5)
57.8 (26.7)
ND
15 (38.3)
0.14 (0.07) 0.70 (0.24)
Cob
NA
NA
NA
NA
NA
NA
NA
NA
Overall average
10 Above ear
9.1 (1.3)
7.0 (1.0)
65.2 (6.0)
56.4 (9.8)
8.0 (4.6)
32.1 (6.7)
2.80 (0.62) 1.24 (0.12)
10 Below ear
4.7 (0.4)
2.9 (0.4)
205 (38.1)
39.3 (5.7)
22.5 (10.7)
137 (25)
4.03 (0.96) 0.97 (0.11)
7 Cob
1.1 (0.2)
2.8 (1.0)
61.9 (27.0)
6.01 (1.7)
15.7 (9.0)
30.4 (13.7)
1.72 (0.29) 0.22 (0.04)
LSDb
1.26
1.10
50.6
9.0
23.4
31.8
0.78
0.13
aabbreviations: LSD, Least significant difference; NA, Not available; NC, not calculated insufficient number of replications to calculated standard error; ND, not
detected
b LSD for among overall average of segments.
6
Supplemental Table 4. Concentrations of plant elements in mg kg-1 (B, Cu, Fe, Mn, Zn, Al), or g kg-1 (Cl, Si) in the stover
fraction above the ear (excluding cob), below the ear, and in the cob at grain harvest of plants collected at several
locations. Some locations collected plants from multiple sites, hybrids or tillages. Values are means with standard error in
parenthesis.
Location
Ames, IA - Char
Ames, IA - no
char
Florence, SC conservation
Florence, SC conventional
Fort Collins, CO conventional
Fort Collins, CO
– no tillage
Lincoln, NE- disk
n
Segment
4
4
4
4
4
4
3
3
3
3
3
3
1
1
1
1
1
1
2
2
Lincoln, NE - no
tillage
2
2
Mandan, ND - 85
day
1
1
1
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
Above ear
Below ear
Cob
B
Cu
Fe
Mn
Zn
Al
Cl
Si
-1
-1
---------------------------------------------- mg kg ------------------------------------------------------------- g kg ------------6.6 (1.3)
5.5 (0.8)
154 (42.9)
16.5 (2.4)
115 (44.2)
105 (50.4)
1.37 (0.04)
1.41 (0.7)
6.2 (0.9)
2.8 (0.3)
654 (74.0)
33.2 (1.7)
107 (23.7)
500 (55.5)
1.01 (0.14)
1.31 (0.10)
2.6 (0.9)
2.0 (0.1)
45.4 (6.6)
3.0 (0.6)
245 (107)
0.7 (NC)
0.93 (0.02)
0.30 (0.07)
7.7 (1.3)
6.3 (0.8)
109 (8.4)
14.6 (1.3)
126 (22.4)
54.2 (7.8)
1.14 (0.18)
1.34 (0.15)
6.3 (0.7)
3.4 (0.3)
871 (50.8)
39.7 (0.8) 83.5 (15.0)
692 (51.1)
0.84 (0.15)
1.28 (0.10)
2.6 (0.5)
2.0 (0.4) 48.8 (12.7)
3.2 (0.3) 74.2 (55.8)
12.3 (NC)
0.73 (0.15)
0.28 (0.05)
3.9 (0.3)
0.7 (0.2)
16.3 (0.9)
14.2 (4.1)
NDa
92.0 (NC)
3.33 (0.29)
0.15 (0.03)
5.3 (0.1)
1.5 (0.6)
34.6 (2.3)
16.0 (5.2)
0.7 (0.7) 42.0 (14.6)
4.19 (0.81)
0.14 (0.02)
0.4 (0.4)
ND
1.9 (1.5)
1.0 (0.5)
ND
13.4 (NC)
3.45 (0.19)
0.03 (0.01)
5.7 (0.6)
2.8 (0.4)
36.5 (5.8)
36.6 (6.9) 13.0 (13.0) 76.4 (17.8)
3.11 (0.26)
0.20 (0.01)
5.5 (0.4)
2.4 (0.2)
124 (19.6)
42.3 (4.5)
2.5 (2.5)
165 (29.9)
4.38 (0.87)
0.20 (0.02)
0.5 (0.2)
0.5 (0.3)
4.8 (0.8)
2.3 (0.3)
ND
ND
4.86 (0.65)
0.04 (0.01)
4.9 (NC)
4.3 (NC)
80.9 (NC)
27.1 (NC)
ND
40.9 (NC)
2.89 (NC)
1.69 (NC)
4.0 (NC)
2.2 (NC)
200 (NC)
27.7 (NC)
ND
164 (NC)
6.41 (NC)
1.23 (NC)
0.2 (NC)
2.1 (NC)
129 (NC)
3.4 (NC)
ND
31.6 (NC)
3.86 (NC)
0.26 (NC)
6.0 (NC)
3.2 (NC)
103 (NC)
35.4 (NC)
ND
57.5 (NC)
3.06 (NC)
1.81 (NC)
4.4 (NC)
2.0 (NC)
81.1 (NC)
24.2 (NC)
ND
75.4 (NC)
7.70 (NC)
1.21 (NC)
0.4 (NC)
1.9 (NC)
95.5 (NC)
4.2 (NC)
1.2 (NC)
18.3 (NC)
3.51 (NC)
0.28 (NC)
4.1 (0.5)
2.9 (0.2)
204 (119)
40.7 (7.0)
ND
128 (89.5)
3.40 (0.45)
0.68 (0.13)
2.6 (0.0)
1.1 (0.2)
440 (129)
37.6 (2.5)
ND
310 (83.2)
4.70 (0.70)
0.58 (0.02)
NA
NA
NA
NA
NA
NA
NA
NA
3.5 (0.2)
2.0 (2.0)
68.0 (3.7)
27.8 (1.2) 18.1 (18.1)
38.3 (3.5)
2.32 (0.02)
0.52 (0.06)
3.2 (0.3)
0.7 (0.5)
123 (57.3)
20.7 (1.3) 30.0 (17.8) 78.9 (46.0)
3.08 (0.26)
0.46 (0.05)
NA
NA
NA
NA
NA
NA
NA
NA
11.3 (NC)
4.7 (NC)
89.4 (NC)
75.9 (NC)
47.9 (NC)
74.9 (NC)
0.15 (NC)
1.62 (NC)
6.3 (NC)
4.7 (NC)
374 (NC)
58.2 (NC)
96.1 (NC)
244 (NC)
0.26 (NC)
1.08 (NC)
2.7 (NC)
0.8 (NC)
11.4 (NC)
7.3 (NC)
75.8 (NC)
59.6 (NC)
0.27 (NC)
0.34 (NC)
7
Mandan, ND –
79 day
1
1
1
2
2
2
2
2
Above ear
8.9 (NC)
3.7 (NC)
83.7 (NC)
57.8 (NC)
432 (NC)
65.2 (NC)
0.47 (NC)
1.63 (NC)
Below ear
6.6 (NC)
3.5 (NC)
190 (NC)
53.7 (NC)
14.6 (NC)
131 (NC)
0.34 (NC)
1.26 (NC)
Cob
2.0 (NC)
ND
7.3 (NC)
4.5 (NC)
450 (NC)
ND
1.13 (NC)
0.215 (NC)
Morris, MN
Above ear
4.7 (0.9)
4.0 (0.8) 52.1 (19.2)
31.3 (5.2) 20.2 (20.2) 51.0 (11.0)
2.09 (0.85)
0.62 (0.01)
Below ear
3.5 (0.6)
1.3 (0.0)
402 (142)
41.8 (7.9)
ND
253 (72.8)
1.87 (0.59)
0.60 (0.01)
Cob
1.1 (0.6)
ND 73.3 (51.4)
5.0 (1.1)
ND
ND
1.72 (0.06)
0.11 (0.01)
St. Paul, MN
Above ear
4.3 (1.0)
5.7 (1.2)
67.5 (1.8) 49.0 (14.2)
ND
16.4 (2.3)
0.06 (0.03)
1.56 (0.03)
Below ear
3.2 (0.0)
4.1 (0.3)
296 (118)
55.8 (8.9)
ND
200 (93.0)
0.12 (0.01)
1.39 (0.03)
Cob
NA
NA
NA
NA
NA
NA
NA
NA
Overall average
12 Above ear
6.0 (0.7)
3.8 (0.5) 88.6 (14.6)
35.6 (5.3) 64.3 (35.8)
66.7 (8.9)
1.95 (0.37)
1.10 (0.18)
12 Below ear
4.8 (0.4)
2.5 (0.4)
316 (72.1)
37.6 (4.0) 27.9 (12.1)
238 (54.7)
2.91 (0.74)
0.90 (0.13)
9 Cob
1.4 (0.4)
1.1 (0.3) 46.4 (15.1)
3.8 (0.6) 93.9 (51.9)
22.6 (8.4)
2.27 (0.55)
0.21 (0.04)
LSDb
0.60
0.56
97.5
5.25
45.2
78.5
0.47
0.15
aabbreviations: LSD, Least significant difference; NA, Not available; NC, not calculated insufficient number of replications to calculated standard error; ND, not
detected
b LSD for among overall average of segments.
8