EVALUATION OF SWITCHGRASS AND SORGHUM BIOMASS POTENTIAL 

Final Report 

1989- 1991 

K.. D. Johnson 

J. H. Cherney 

D. K.Greene 

J. J. Volenec 

Department of Agronomy 

Purdue University 

West Lafayette, IN 47907-1150 

Research supported by 

Biofuels Systems Division 

Office of Transportation Technologies 

Activity No. EB 24 01 00 0 

Report prepared by 

Department of Agronomy 

Purdue University 

West Lafayette, Indiana 47907-1150 

under Subcontract 19X-27412C 

for 

Herbaceous Energy Crops Program 

Environmental Sciences Division 

OAKRIDGE NATIONAL LABORATORY 

Oak Ridge, Tennessee 37831-6285 

operated b)' 

MARTIN MARIETTA ENERGY SYSTEMS, INC. 

for the 

U.S. DEPARTMENT OF ENERGY 

under Contract DE-AC05-840R21400 

TABLE OF CONTENTS 

TABLE OF CONTENTS m 

LIST OF FIGURES v 

LIST OF TABLES vii 

ABSTRACT ix 

INTRODUCTION 1 

OBJECTIVES 2 

PROCEDURES 3 

Objective 1. Evaluate dry matter loss and composition 3 

changes when storing switchgrass. 

Objective 2. Evaluate lodging resistance and yield potential 4 

in sorghum. 

RESULTS AND DISCUSSION 5 

Objective 1-Dry Matter Loss. 5 

Constituent Results. 9 

Objective 2- Evaluate lodging resistance and yield potential 13 

in sorghum. 

CONCLUSIONS 16 

Objective 1. Evaluate dry matter loss and composition 16 

changes when storing switchgrass. 

Objective 2. Evaluate lodging resistance and yield potential 16 

in sorghum. 

REFERENCES 17 

iii 

LIST OF FIGURES 

Fi~mre 

1 Composition of unweathered, weathered and composite samples of 

switchgrass hay averaged over 2 locations, 3 replicates, 2 surfaces and two 

wrap types. P <0.05 for NDF and <0.01 for ADF, Nand ash. 

2 Composition of switchgrass composite samples taken on three dates. Values 

are the means of 2 locations, 3 replicates, 2 surfaces and two wrap types. P 

<0.01 for NDF and < 0.05 for ADF and N. 

3 Acid detergent fiber composition of switchgrass hay stored on sod or crushed 

rock and bound with twine or netting. Values are means of 2locations and 3 

replicates. P < 0.05 for Storage surface x Wrap x Sample type interaction. 

4 Ash composition of switchgrass hay stored on sod or crushed rock and bound 

with twine or netting. Values are means of 2locations and 3 replicates. P 

< 0.05 for Storage surface x Wrap x Sample type interaction. 

5 Neutral detergent fiber composition of switchgrass and tall fescue hay bound 

by netting, twine or plastic sleeve. Values are means of 3 replicates, 3 

sampling dates and 2 storage surfaces. P < 0.01 for Species x Wrap 

interaction. 

6 Acid detergent fiber composition of switchgrass and tall fescue hay bound by 

netting, twine or plastic sleeve. Values are means of 3 replicates, 3 sampling 

dates and 2 storage surfaces. P <0.01 for Species x Wrap interaction. 

7 Nitrogen composition of switchgrass and tall fescue hay bound by netting, 

twine or plastic sleeve. Values are means of 3 replicates, 3 sampling dates 

and 2 storage surfaces. P <0.05 for Species x Wrap interaction. 

8 Neutral detergent fiber composition of hay stored on the ground, crushed 

rock and inside. Values are means of 3 replicates, 2 species and 3 sampling 

dates. P <0.05. 

v 

LIST OF TABLES 

1 Percentage original dry matter of switchgrass or tall fescue large round bales 

recovered when stored on sod, crushed rock or inside and bound together 

with twine, netting or black plastic sleeve. 

2 Percentage original dry matter of switchgrass large round bales recovered 

when stored on sod or crushed rock and bound together with twine or netting. 

3 Mean total biomass yield, grain yield, height and lodging score of sorghum 

planted at two sites in 1990. 

vii 

ABSTRACT 

Investigation as to ways to reduce dry matter losses and compositional 

changes while storing herbaceous feedstocks are needed. Also, crop production 

practices that reduce the incidence of lodging in some high yielding sorghum 

genotypes without giving up dry matter yield is a concern. Our objectives were to 

evaluate storage losses and compositional changes associated with switchgrass and 

tall fescue packaged as large round hay bales and to evaluate whether lodging of 

sorghum could be reduced by altering with-in row spacing of high-yielding sorghum 

genotypes. 

Storage surface and wrap type had greatest impact on dry matter recovery 

and not compositional changes of the herbaceous feedstock. Storing large round 

bales on crushed rock was superior to storage on sod for recoverability of 

unweathered dry matter and total dry matter. Switchgrass had less loss than tall 

fescue. Binding bales with twine as compared to netting resulted in 6.6 percentage 

units less total recoverable switchgrass dry matter. Small increases in fiber and 

nitrogen composition were apparent in samples taken as probings from the outer 

bale surface exposed to air. Unweathered switchgrass had lower fiber content as 

compared to weathered samples, with greatest difference in the acid detergent fiber 

fraction, 5.4 percentage units. Inside storage of large round bales does not appear to 

be economical as lower storage cost alternatives are available for the storage of 

herbaceous biomass. 

Targeted populations of 4.3 x 104 and 2.6 x 105 sorghum plants ha-l resulted 

in no significant dry matter yield differences. Yield at the lower population was 

maintained by greater dry matter accumulation within individual tillers, as the 

greater population actually had approximately two times the number of tillers m-2.In 

general, the lower plant population did reduce lodging, but the response was not 

consistent among genotypes. Breeding for lodging resistance should not be 

deemphasized in place of reducing the problem with cultural practices. 

JOHNSON, K.D., J.H. CHERNEY, D.K. GREENE AND J.J. VOLENEC. 

Evaluation of switchgrass and sorJ;dlum biomass potential. 1992. Oak Ridge 

National Laboratory, Oak Ridge, TN. 17 pp. 

ix 

INTRODUCTION 

Previous research conducted by Purdue University agronomists indicated that 

the perennial warm-season grass, switchgrass (Panicum virgatum L ), and many 

annual forage sorghums (Sorghum bicolor (L) Moench.) are viable candidates for 

herbaceous biomass crops (Cherney et al., 1990). 

Ways to store feedstocks prior to their conversion to biofuels need to be 

investigated so as to reduce dry matter losses and changes in constituent 

composition. The cost of a pole barn for inside storage may not be an economical 

alternative(Petritz et al., 1989). Various plastic wraps and netting currently are 

available to protect bales stored outside. 

Previous work on losses associated with the storage of grass and alfalfa-grass 

(Medicago sativa L.) large round bales (Lechtenberg et al., 1979) indicated that 

storing bales on a crushed rock surface reduced losses 8. 7 percentage units as 

compared to storage directly on the ground (85.5% and 76.8%, respectively). Data 

suggested that 57% of the storage loss associated with outside storage of large round 

bales is at the bale-soil interface. Ninety-two percent of hay stored inside was 

recovered at the end of storage; the unrecovered hay represents dry matter loss as no 

weathering was experienced with inside storage. Mouzin (1984) compared spoilage 

loss of tall fescue (Festuca arundinacea Schreb.) and tall fescue-red clover (Trifolium 

pratense L) large round bales when stored inside, outside with plastic wrap or outside 

with no protection. Bales wrapped with plastic had spoilage dry matter losses that 

were 10 percent lower than bales stored outside. Hay stored inside had no weather 

damage loss. 

It is efficient and feasible to harvest switchgrass in the form of large round 

bales and then subsequently store these bales outside. Dry matter losses during 

storage of mature switchgrass in the Midwest as large round bales, however, is not 

known. A Missouri study investigated storage losses from relatively immature 

switchgrass in large round bales. Eight bales stored in a barn averaged 3.2% dry 

matter storage loss after 13 months. Ten bales stored outside ranged from 6.5 to 

30.1% dry matter loss. These relatively large outside losses were, in part, due to 

heavy rainfall occurences. 

2 

Most dry matter lost from bales is the soluble, non-fiber component. This 

results in an increase in the proportion of fiber in dry matter (Cherney et al., 1987). 

If moisture content of the crop is too high at baling without the addition of an 

effective preservative, heating will occur and result in an inferior product. 

Composition of weathered hay in the Lechtenberg et al. study had lower in vitro dry 

matter digestibility and acid detergent fiber values and higher total nitrogen (N) and 

lignin values as compared to the unweathered fraction. When bales were stored 

outside without protection, lower in vitro dry matter digestibility resulted 

(Mouzin,1984); no matter the storage method utilized, crude protein, acid detergent 

fiber, neutral detergent fiber, and lignin increased whereas in vitro dry matter 

digestibility decreased during storage. 

Research with tall-growing forage sorghums at Purdue University indicated 

that some high-producing genotypes have potential as a feedstock, but lodging was a 

concern with several genotypes studied (Cherney et a1.,1990). In an attempt to 

reduce lodging associated with a single harvest and not sacrifice total yield, two 

cuttings were harvested during the growing season. Lodging was reduced 

significantly for lodging-prone genotypes when two harvests were taken, however dry 

matter yield was reduced so significantly that this was not a viable cropping option. 

Alternative cultural practices deserve consideration for their influence upon reducing 

the number of lodged plants. 

Caravetta et a1.(1990) noted significant tiller habit differences among four 

sorghum genotypes when grown under varied within-row spacings. A linear decrease 

in dry matter yield was reported when within-row spacing increased from 5 em to 60 

em. Increased within-row spacing decreased plant height and leaf:stem ratio in three 

of the four genotypes, suggesting that lodging may be reduced as within-row spacing 

increases. 

OBJECTIVES 

Research was divided into two distinct objectives as follows: 

1. Evaluate dry matter losses and composition changes when switchgrass is 

harvested as hay and packaged in large round hay bales. 

2. Evaluate lodging resistance and yield potential in sorghum when planted at 

two populations. 

3 

PROCEDURES 

Objective 1. Evaluate dry matter loss and composition changes when storing 

switchgrass. Two hectares of Cave-in-Rock switchgrass were no-till established into 

an area that was predominantly tall fescue and reed canarygrass (Phalaris 

arundinacea L) at the Southern Indiana Purdue Agricultural Center (SIP AC) , 

Dubois, IN, in the spring of 1989. Stand establishment was successful, although some 

reed canarygrass survived the application of glyphosate used to kill the cool-season 

grasses. Broadleaf weeds were controlled with an application of dicamba in the 

summer of 1989. Following burning of residue in early spring 1990, reed canarygrass 

was controlled with an application of atrazine. Switchgrass was fertilized with 168 kg 

N ha -

1 in early May and harvested as hay in late July with a Claas Rollant 66large 

round baler. This baler has the ability to bind bales with twine or plastic netting. 

Switchgrass yielded approximately 6.2 Mg ha -

1

, an acceptable yield for the rolling 

terrain and year following establishment. Availability of tall fescue, a very common 

cool-season grass species with herbaceous biomass possibilities, provided an 

opportunity to compare two different grass species with different methods of storage 

at SIP AC. The Feldun-Purdue Agricultural Center (Feldun-P AC), Bedford, IN, was 

used as a second environment for the comparison of some switchgrass treatments. 

Number of switchgrass bales was limited so all treatments could not be utilized at 

both sites. 

Tall fescue was placed on trial June 14, 1990, whereas switchgrass was placed 

on trial August 2 and 3, 1990. The reason for this differential in beginning time is 

because tall fescue is a cool-season species and is harvested approximately four to six 

weeks earlier than the warm-season species switchgrass. Thus, as species are 

evaluated one should recognize the six-week time frame difference because more 

weathering of tall fescue would be expected. Bales were placed on tall fescue sod or 

number 2 crushed limestone. Black plastic sleeves were manually put on bales 

initially bound with twine. 

Each bale was weighed and cored with a hay probe for compositional analyses 

prior to being placed on trial and at the end of the study (May 7, and 8, 9 and 15, 

1991 at Feldun-PAC and SIPAC, respectively); also, all bales were cored on 

December 14, 1990. Dry matter losses associated with storage of switchgrass and tall 

fescue large round bales were determined. Percentage of unweathered dry matter, 

recoverable weathered dry matter and total recovered dry matter as a percent of the 

original bale dry matter weight were parameters measured. Weathered hay was 

subjectively considered to be hay that would no~ be consumed by livestock. 

Weathered hay was hand separated from unweathered hay on the May, 1991 dates 

noted above and its wet weight was recorded. Subsamples of weathered hay and the 

probed composite and unweathered samples were weighed, dried at 60° C , weighed 

again for a measure of dry matter content, ground with a Wiley mill to pass a 3-mm 

screen and reground with a cyclone mill to pass a 1-mm screen. 

Ground samples were scanned with a near infrared reflectance reflectance 

spectrophotometer (Pacific Scientific model 6250). The spectrophotometer's 

computer program selected samples that were analyzed in the laboratory for neutral 

detergent fiber (NDF), acid detergent fiber (ADF), ash and nitrogen. The NDF 

procedure was used to separate fiber and soluble cell components (Goering and Van 

Soest, 1970). The ADF procedure removes hemicellulose from the cell wall fraction. 

Nitrogen content was determined using a micro-Kjeldahl technique. The standard 

error of prediction using the spectrophotometer for NDF, ADF, ash and N were 

1.78, 1.76, 0.73 and 0.14, respectively. Correlation coefficients for NDF, ADF, ash 

and N were 0.95,0.88, 0.93 and 0.95 , respectively. 

The statistical design at SIP AC was a randomized complete block with a splitsplit-split plot arrangement. Surface (crushed rock versus sod) was the first split, 

grass species (tall fescue versus switch grass) was the second split and the third split 

was wrap (twine versus net versus black plastic sleeve). The statistical design for the 

switchgrass comparisons at the two sites (Feldun-P AC and SIP AC) was a nested 

split-split plot design with replications nested within site, surface (crushed rock versus 

sod) being the first split and wrap (twine versus netting) being the second split. The 

treatments were replicated three times. An inside storage treatment ( ag lime on the 

ground and under a pole shed) was utilized as a comparison to outside storage 

options. Analysis of variance procedures were used to analyze data and statistical 

differences presumed when probability of a larger F statistic was less than 0.05. 

Objective 2. Evaluate lodging resistance and yield potential in sorghum. 

Areas at Throckmorton-Purdue Agricultural Center (TPAC), Romney, IN, and 

SIP AC were selected for these studies. Soil amendments were applied as needed 

according to soil tests and conventionally tilled seedbeds prepared. 

5 

Eighteen sorghum genotypes were planted on May 10 and June 14 at TPAC 

and SIP AC, respectively, in a randomized complete block split plot statistical design 

with three replications. Genotype was the main plot and plant population was the 

split plot. The late date of planting at SIP AC was unavoidable because of wet 

conditions. Genotypes selected were high producing genotypes from studies 

previously conducted in Indiana (Cherney et al., 1990) , Kansas and Oklahoma. 

Genotypes included were Asgrow Titan R, Casterline Silo Plus, DK FS25E, Funks 

--·~-- -~------

G 1990, Garrison Seed Sile -All, Golden Harvest H-58, Grassl, Meridian 81E sweet 

sorghum, NC+ 965, NK Sucrosorgo 506, PAG FS466, Pioneer 811F, Pioneer 931, 

Taylor-Evans Silo Maker, Taylor-Evans Milk Maker, Vartan 3, Vartan 2319 and 

Vartan 3192. A corn hybrid, DK 711, was included for a yield comparison. Targeted 

plant populations were 4.3 X 104 and 2.58x 105 plants ha-l for sorghum and 8.6x 

104 plants ha-1 for corn. Row width was 76.2 em. 

Nitrogen was applied after seeding at a rate of 200 kg ha-l as ammonium 

nitrate. Weed control was accomplished using 1.3 and 3.36 kg ha-1 active ingredient 

atrazine and propachlor, repectively,and applied after seeding. 

Sorghum harvest occurred on October 3 and 12 at TP AC and SIP AC, 

respectively. Tiller count, height and lodging score measurements were taken at 

harvest. Data were analyzed using analysis of variance procedures and significance 

considered when probabilitity of a larger F statistic was less than 0.05. 

RESULTS AND DISCUSSION 

Objective 1 - Dry Matter Loss. Table 1 provides complete detail of dry 

matter losses. Storage of large round bales on crushed rock was superior to storage 

on sod. Storing the bales on crushed rock resulted in 4.7 and 3.7 percentage units 

more unweathered dry matter and total dry matter recovered, respectively. 

Switchgrass was superior to tall fescue in terms of recoverable unweathered and total 

dry matter values. The black plastic sleeve (ends open) and netting were superior to 

twine for the amount of unweathered and total dry matter recovered as a percent of 

the original bale dry matter. 

Amount of weathered material associated with the black plastic sleeve storage 

treatment was not as great as other treatments, but was greater than hypothesized. 

The moisture content of this weathered material was very high and was 

6 

predominantly at the lower portion of the sleeved bale. From a practical standpoint, 

loss of bales bound together by twine and stored on sod presented the greatest 

problem in terms of gathering recoverable weathered material; experimentally, the 

weathered forage in contact with the soil surface was gathered with a pitchfork. It is 

unlikely that it will be cost-effective for a biomass conversion facility to recover 

rotted material at the interface of the bale and ground. A question that needs to be 

addressed is whether the presence of weathered material is deleterious to the 

conversion of the feedstock to energy. If weathered material has undesirable 

characteristics for the conversion to energy, then method of protecting the feedstock 

will be potentially different than if weathered material has a similar fuel value as 

unweathered material. 

When comparing results of storing large round bales outside as compared to 

inside, total amount of dry matter recovered is similar, except when bales are stored 

on sod with twine. Cost of storing tall fescue and switchgrass feedstocks as large 

round bales in an inside storage facility is not a viable alternative. 

When analyzing the switchgrass data from two locations, the superiority of 

storing the bales on crushed rock as compared to storing them on sod is again 

apparent (Table 2). No significant differences were attributed to site. This is 

significant as the Feldun-PAC site had 15.5 em less precipitation than SIPAC during 

the period of study (August 1990-May 1991). While the two-way interaction of wrap 

(twine versus net) and storage surface (sod versus rock) is not statistically significant 

(P > 0.05), possibly because of a poor power of test (one degree of freedom in the 

numerator and fifteen in the denominator), the results suggest a measure of practical 

importance. Total recoverable amount of switchgrass is similar when netted bales 

are stored on sod or rock (Table 2); however, there is a greater differential in favor 

of the crushed rock surface when twine-bound switchgrass bales are stored on sod. 

Wrapping bales with twine as compared to netting resulted in 6.6 percentage units 

less total recoverable switchgrass dry matter. No significant difference in recoverable 

weathered material was noted when comparing netting to twine. 

Table 1. Percentage original dry matter of switchgrass or tall fescue large round bales recovered when stored on sod, crushed rock or insid

netting or black plastic sleeve. 

Unweathered 

Storage Surface Twine Net Sleeve 

Switch grass 

Recoverable 

Weathered 

Twine Net Sleeve 

Total 

Twine Net Sleeve 

Unweathered 

Twine Net Sleeve 

Tall Fescue 

Recoverabl

Weathere

Twine Net 

----------------------------------------------------------------------------------------------% of Original Dry Matter----------------------

Sod 87.4 91.3 91.5 

Rock 93.7 95.4 94.3 

Inside 99.2 

Main effect of "Storage Surface (Sod vs. Rock)" 

P < .01 Unweathered P = 0.1 Recoverable Weathered P < .01 Total 

4.3 5.1 

3.0 2.8 

Main effect of "Grass Species (Switch grass vs. Tall fescue)" 

P < .01 Unweathered P < .01 Total 

5.0 91.7 5.3 96.7 

96.4 96.5 79.4 86.9 89.4 4.3 5.1 

98.2 99.6 88.1 89.3 93.2 3.4 3.9 

92.6 

Main effect of"Wrap (Twine vs. Net vs. Sleeve)" 

P < .01 Unweathered; BLSD (k= 100, P approx. = .05

P < .01 Total; BLSD (k= 100, P approx. =.05) = 2.4 

Table 2. Percentage original dry matter of switchgrass large round bales recovered when stored on sod 

bound together with twine or netting. 

Twine Net 

Storage Surface Unweathered Recoverable Weathered Total Unweathered Recoverable 

-----------------------------------------------------% of Original Dry Matter--------------------------

Sod 

Rock 

80.7 

92.5 

4.5 

3.7 

Main effect of"Storage Surface (Sod vs. Rock)" 

Unweathered P = .03 

Recoverable Weathered P = .03 

Total P = .04 

Main effect of 'Wrap (Twine vs. Net)" 

Unweathered 

Total 

P= .04 P= .03 

85.2 

%.2 

92.3 

95.5 

4.4 

2.6 

9 

Material and labor costs expended to store the herbaceous feedstock and 

value of the feedstock will dictate what storage procedure is most economical. 

Current cost of netting is two to three times the needed amount of twine used to bind 

large round bales. Price is dependent upon the size of large round bale which varies 

from a 1.22 to 1.70 m width (personal communication with Ford New Holland 

representative). For instance, a 1.22 m bale will cost approximately $0.63 for netting 

and $0.28 for twine. A 1.70 m bale will cost $1.18 to be bound with netting and only 

$0.37 to be bound with twine. A factor in favor of the use of netting, however, is that 

capacity (number of bales packaged per hour) has been documented to be at least 

34% greater (personal communication with M & W Gear representative). Cost of a 

black plastic sleeve used in this study was $1.65 and re-use is very difficult. Cost of 

twine is also incurred when plastic sleeves are utilized. Current price of crushed 

limestone laid 15-cm thick is $1.09 per m

2. Assuming that a large round bale 

requires 3.3 m

2 of surface rock and that the rock will provide an effective surface for 

four years without further addition of rock suggests that prorated cost will be $0.90 

each year. Also, when rock is added again, it will be in a smaller amount than the 

amount initially needed. 

Constituent Results. No differences were apparent between the two locations 

(SIPAC and Feldun-P AC) for quality constituents of switchgrass. Quality analyses 

on samples taken at the completion of the study indicate that unweathered 

switchgrass had the lowest NDF and ADFvalues (Figure 1). The weathered 

switchgrass had the greatest ADF, N and ash contents. As a result, hemicellulose 

content (NDF- ADF) was approximately 4 percentage units lower in weathered 

samples. 

80 ..... 

Q) 

-+--' 60 -+--' 

0 

:::E 

;::-. 40 

0 

-0 20 ~ 

0 

73.975.375.7 

NDF ADF 

o Unweathered 

11 Weathered 

11 Composite 

1.2 1.5 1.1 4.5 6.4 4.3 

N Ash 

Figure 1. Composition of unweathered, weathered and composite samples of 

switchgrass hay averaged over 2 locations, 3 replicates, 2 surfaces and two wrap 

types. P < 0.05 for NDF and <0.01 for ADF, Nand ash. 

10 

Composite samples are cored samples from the exposed portion of the bales 

and do not include weathered material from the interface of soil and bale. With the 

exception of NDF, composite samples had similar values to unweathered switchgrass 

(Figure 1). Composite samples of switchgrass had very small increases in NDF, ADF 

and N values as time progressed from experiment initiation to completion (Figure 2). 

These data suggest that greatest concern about deterioration of switchgrass is not the 

surface exposed to the air but the surface in contact with the soil. 

80 74.5 

..... 

2 

0 60 

:::::::!! 

>-, 

..... 40 

0 

-0 20 ~ 

0 

75.8 75.7 

1 

NDF ADF 

0 Aug-90 

11 Dec-90 

Iii May-91 

1 1.1 

N 

Figure 2. Composition of switchgrass composite samples taken on three dates. 

Values are the means of 2locations, 3 replicates, 2 surfaces and two wrap types. P < 

0.01 for NDF and < 0.05 for ADF and N. 

While there were significant three-way interactions with surface treatment 

(sod or rock), wrap (twine or net) and sample type (unweathered, weathered or 

composite) for ADF and ash content (Figures 3 and 4), their importance is 

overshadowed by the effects surface and wrap type have upon dry matter losses. 

Weathered switchgrass that had been stored on rock and covered with netting had a 

lower ADF, whereas weathered switchgrass stored on the ground and bound with 

netting had approximately 2 percentage units more ash content than the other 

treatments. 

..... 

(!) 55 __. 

__. 

0 

::a: 

~ 50 

0 

-0 45 ~ 

LJ,_:' 

0 40 

< 

11 

lo Unweathered II Weathered Iii Composite 

50.4 

Sod, 

Net 

Sod, 

Twine 

Rock, 

Net 

50.2 

Rock, 

Twine 

Figure 3. Acid detergent fiber composition of switchgrass hay stored on sod or 

crushed rock and bound with twine or netting. Values are means of 2locations and 3 

replicates. P < 0.05 for Storage surface x Wrap x Sample type interaction. 

-0 

~ 

lo Unweathered 11 Weathered Iii Composite 

7.98 

Sod, 

Net 

Sod, 

Twine 

Rock, 

Net 

Rock, 

Twine 

Figure 4. Ash composition of switchgrass hay stored on sod or crushed rock and 

bound with twine or netting. Values are means of 2locations and 3 replicates. 

P < 0.05 for Storage surface x Wrap x Sample type interaction. 

The study at SIP AC permitted comparison of two herbaceous biomass 

species, switchgrass and tall fescue, when stored as large round bales. As one would 

predict based upon previous comparisons of switchgrass and tall fescue, switchgrass 

had higher fiber values and lower N content than tall fescue (Figures 5, 6 and 7, P 

< 0.01 ). There were significant two-way interactions of species and wrap type for 

NDF, ADF and N. Switchgrass composite samples had similar NDF, ADF and N 

values regardless of wrap, whereas tall fescue bound with netting had approximately 

five and 2.5 percentage units increase for NDF and ADF, respectively, as compared 

to bales bound with twine or a plastic sleeve (Figures 5 and 6). Tall fescue bales 

wrapped with netting had a slightly lower N content than plastic sleeved or twinebound bales (Figure 7). 

12 

80 ..._ 75.7 75.6 75.1 (l) 

-........ 0 

:::::iE 70 

2:" 

Cl 

lo Net 11 Twine BJ Sleeve I 

64 

'-+-

0 

N 60 

50 

Swltchgrass Tall Fescue 

Figure 5. Neutral detergent fiber composition of switchgrass and tall fescue hay 

bound by netting, twine or plastic sleeve. Values are means of 3 replicates, 3 

sampling dates and 2 storage surfaces. P < 0.01 for Species x Wrap interaction. 

50 ..._ 

(l) 45.6 45.4 45.3 lo Net BD Sleeve! ........ 11 Twine __. 

0 

::::::!: 

2:" 40 

a 40 -0 

N 

w.: 

a 

<( 

30 

Switch grass Tall Fescue 

Figure 6. Acid detergent fiber composition of switchgrass and tall fescue hay bound 

by netting, twine or plastic sleeve. Values are means of 3 re:plicates, 3 sampling dates 

and 2 storage surfaces. P <0.01 for Species x Wrap interaction. 

13 

2 lo Net 11 Twine It Sleeve! 

1.51 

1.7 1.66 

1.5 

1.05 1.05 1.03 

1 

0.5 

:z 

a ......... .__ __ 

Switchgrass Tall Fescue 

Figure 7. Nitrogen composition of switchgrass and tall fescue hay bound by netting, 

twine or plastic sleeve. Values are means of 3 replicates, 3 sampling dates and 2 

storage surfaces. P < 0.05 for Species x Wrap interaction. 

losod 11 Rock lllnsidej 70 ....... 68.1 <l) 

........ 66.8 ---0 

~ 

~ Cl 

........ 65 0 

~ 

u...-

Cl 

:z 

60 

Figure 8. Neutral detergent fiber composition of hay stored on sod, crushed rock and 

inside. Values are means of 3 replicates, 2 species and 3 sampling dates. P <0.05. 

Surface (sod, crushed rock or inside) had little impact on the constituency of 

probed samples taken from twine bound bales at the end of the trial, indicating again 

that greatest concern is the interface of the bale surface and soil and not the portion 

of the bale exposed to the air. When averaged across grass species, NDF content of 

rock-stored bales for some unexplainable reason had a slightly higher NDF (Figure 

8). 

Objective 2 - Evaluate lodging resistance and yield potential in sorghum. 

Total biomass and grain yields were higher at TP AC than at SIP AC (data not 

shown). Undoubtedly, much of the reduced yield at SIPACwas due to late planting 

14 

because of wet soil conditions. Top producing genotypes included Pioneer 931, 

Vartan 3192, Northrup King Sucrosorgo 506, Grassl and Vartan 3 (Table 3). 

Greatest biomass production did not come from genotypes producing the most grain. 

A tall growing com hybrid, Dekalb 711, yielded 23.95 and 22.26 Mg ha-l total 

biomass at Throckmorton-PAC and SIPAC, respectively. Corn grain accounted for 

40.7 and 52.2% of the total dry matter prodl!ction at TPAC and SIP AC, respectively. 

The tallest growing cultivar, Vartan 2319, was only intermediate in total 

biomass yield (Table 3). Lodging resistance is critical for top yields. All high yielding 

cultivars, except Grassl, had an average lodging score greater than four (Table 3). 

The lower plant population, in general, did reduce lodging, although for Pioneer 

811F, Vartan 3 and Vartan 2319 the higher plant population had no effect on lodging 

or there was an arithmetically higher lodging score. Grassl, a high yielding genotype, 

had substantial reduction in lodging at the lower plant population. 

A sixfold greater plant population resulted in 2.25 and 1.78 greater tillers m·

2 

at TP AC and SIPAC, respectively. An increase in plant population, however, did not 

improve biomass yield. Yield at the lower plant population was maintained by 

individual tillers accumulating more dry matter than tillers at the higher plant 

population. Tiller number per square meter is not the key factor in determining 

biomass yield. Highest yielding genotypes had a range of 20.7 and 13.1 tillers m2

. 

15 

Table 3. Mean total biomass yield, grain yield, height and lodging score of sorghum 

:Qlanted at two sites in 1990. 

Lodginia 

Yield Height Pop. ha-1 

Genotype Total Grain 4.3x104 2.6xl05 

-1 --Mgha -- -m- l=flat, 

5=erect 

Pioneer931 24.67 2.02 4.64 4.92 4.83 

Vartan3192 24.08 0.10 4.37 4.50 4.17 

NK. Sucrosorgo 506 22.65 1.48 4.36 5.00 4.92 

Grassl 21.69 0.28 3.69 4.22 3.08 

Vartan3 20.60 0.01 4.21 4.67 4.88 

FunksG 1990 19.71 0 3.74 5.00 4.92 

Vartan 2319 19.69 .01 5.08 4.00 4.17 

Pioneer 811F 19.21 0 3.38 5.00 5.00 

Golden Harvest H-58 18.65 3.07 3.32 3.83 3.67 

Meridian 81E 18.28 1.11 3.68 4.22 3.67 

Asgrow Titan R 17.84 5.30 2.78 3.00 2.00 

Taylor-Evans Milk:maker 17.71 4.14 3.04 2.08 1.67 

DeKalb FS25E 17.48 4.09 3.00 4.33 2.42 

Casterline Silo Plus 16.99 4.29 2.91 2.00 1.50 

Taylor-Evans SHomaker 16.95 5.49 2.58 3.58 1.00 

Ga!'-Pson Seed Site-All 16.51 4.78 2.96 2.08 1.50 

NC 965 16.46 2.68 3.29 3.58 3.17 

PAGFS466 16.37 3.96 2.47 4.08 2.92 

BI.SDb 4.39 2.09 0.32 

a Main effect of population significant at P=0.06. b Bayes least significant difference (P approximately = 0.05). 

16 

CONCLUSIONS 

Objective 1. Evaluate dry matter loss and composition changes when storing 

switchgrass. A crushed rock surface is superior in terms of total recoverable dry 

matter as compared to storage on sod. Total recoverable dry matter was greatest 

with the use of a sleeve or netting, but cost may dictate that the small increase in 

recoverable dry matter (four to six percentage units) is not worth the added cost. An 

"inside" treatment comparison of dry matter recovered suggests that inside storage is 

not justified. When one considers the cost associated with building a structure it is 

not a viable alternative when utilizing switchgrass and tall fescue herbaceous biomass 

in an environment and length of time similar to the studies conducted in Indiana. 

When considering the extra amount of feedstock not able to be picked up by 

mechanical means without aid of manual labor when large round bales are stored on 

sod with twine, this method of storage appears to be least satisfactory. 

The importance storage surface and wrap has on feedstock constituency is 

overshadowed by their effects on dry matter losses. Greatest concern about 

deterioration of feedstock quality is not the surface of the large round bale exposed 

to the air but the surface in contact with the soil. Analyses taken at the completion of 

the study indicate that unweathered switchgrass had the lowest NDF and ADF 

values. Weathered switchgrass had the greatestADF, Nand ash contents. As a 

result, hemicellulose content was approximately 4 percentage units lower in 

weathered samples. 

Switchgrass composite samples had similar NDF, ADF and N values 

regardless of wrap, whereas tall fescue bound with netting had approximately five 

and 2.5 percentage units increase for NDF and ADF, respectively, as compared to 

bales bound with twine or a plastic sleeve. 

Objective 2 - Evaluate lodging resistance and yield potential in sorghum. 

Photoperiod-sensitive and hybrid sorghums that were able to utilize an entire 

growing season were very productive with yields greater than 20 Mg ha -

1 

common. 

A lower plant population was effective in reducing lodging without significant yield 

loss. Lodging resistance is critical for top yields. Highest yielding genotypes were 

Pioneer 931, Vartan 3192, NK Sucrosorgo 506, Grassl and Vartan 3. Tiller number 

per square meter was not a major yield determining factor as at the lesser plant 

population individual tillers accumulated more dry matter. 

17 

REFERENCES 

Caravetta, G.J., J.H. Cherney, and K.D. Johnson. 1990. Within-row spacing 

influences on diverse sorghum genotypes: I. Morphology. Agron. J. 82:206-210. 

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compositional changes in alfalfa hay treated with sodium diacetate and stored at 

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