EVALUATION OF SWITCHGRASS AND SORGHUM BIOMASS POTENTIAL

Final Report

1989- 1991

K.. D. Johnson J. H. Cherney D. K.Greene J. J. Volenec

Department ofAgronomy Purdue University West Lafayette, IN 47907-1150

Research supported by Biofuels Systems Division Office ofTransportation Technologies Activity No. EB 24 01 00 0

Report prepared by Department ofAgronomy 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 operatedb)' MARTIN MARIETTAENERGY SYSTEMS, INC. for the U.S. DEPARTMENT OF ENERGY under Contract DE-AC05-840R21400TABLE OF CONTENTS



### TABLE OF CONTENTS m LIST OFFIGURES v LIST OFTABLES 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-DryMatterLoss. 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

iiiLIST OF FIGURES**Fi~mre** 

### 1 Composition ofunweathered, 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 ofswitchgrass composite samples taken on three dates. Values

are the means of2 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 ornetting. Values are means of2locations and 3 replicates. P 

### < 0.05 for Storage surface xWrap x Sample type interaction.

4 Ash composition ofswitchgrass hay stored on sod or crushed rock and bound with twine or netting. Values are means of2locations and 3 replicates. P


### < 0.05 for Storage surface xWrap x Sample type interaction.

5 Neutral detergent fiber composition ofswitchgrass and tall fescue hay bound by netting, twine or plastic sleeve. Values are means of3 replicates, 3 sampling dates and 2 storage surfaces. P 

### < 0.01 for Species x Wrap interaction.

6 Acid detergent fiber composition ofswitchgrass and tall fescue hay bound by netting, twine or plastic sleeve. Values are means of3 replicates, 3 sampling dates and 2 storage surfaces. P 

### <0.01 for Species x Wrap interaction.

7 Nitrogen composition ofswitchgrass and tall fescue hay bound by netting, twine or plastic sleeve. Values are means of3 replicates, 3 sampling dates and 2 storage surfaces. P 

### <0.05 for Species xWrap interaction.

8 Neutral detergent fiber composition ofhay stored on the ground, crushed rock and inside. Values are means of3 replicates, 2 species and 3 sampling dates. P 

### <0.05.

v

### LIST OF TABLES

1 

### Percentage original dry matter ofswitchgrass or tall fescue large round bales recovered when stored on sod, crushed rock or inside and bound together with twine, netting orblack plastic sleeve.

2 Percentage original dry matter ofswitchgrass 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 ofsorghum planted at two sites in 1990.

viiABSTRACT

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 oflodging in some high yielding sorghum genotypes without giving up dry matteryield 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 ofhigh-yielding sorghum genotypes. Storage surface and wrap type had greatest impact on dry matter recovery and not compositional changes ofthe 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. Bindingbales 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 oflarge round bales does not appear to be economical as lower storage cost alternatives are available for the storage of herbaceous biomass. Targeted populations of4.3 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 oftillers 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 ofreducing the problem with cultural practices.

JOHNSON, K.D., J.H. CHERNEY, D.K. GREENEAND J.J. VOLENEC. Evaluation ofswitchgrass and sorJ;dlum biomass potential. 1992. Oak Ridge National Laboratory, Oak Ridge,TN. 17 pp.

ixINTRODUCTION

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 ofa 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 ofgrass 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% ofthe storage loss associated with outside storage oflarge round bales is at the bale-soil interface. Ninety-two percent ofhay stored inside was recovered at the end ofstorage; the unrecovered hay represents dry matter loss as no weatheringwas experienced with inside storage. Mouzin (1984) compared spoilage loss oftall 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 oflarge round bales and then subsequently store these bales outside. Dry matter losses during storage ofmature 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 offiber in dry matter (Cherney et al., 1987). Ifmoisture content ofthe crop is too high at baling without the addition ofan effective preservative, heating will occur and result in an inferior product. Composition ofweathered 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 matteryield was reduced so significantly that this was not a viable cropping option. Alternative cultural practices deserve consideration for their influence upon reducing the number oflodged plants.

Caravetta et a1.(1990) noted significant tiller habit differences among four sorghum genotypes when grown undervaried within-row spacings. A linear decrease in dry matteryield was reported when within-row spacing increased from 5em to 60

em. Increased within-row spacing decreased plant height and leaf:stem ratio in three ofthe 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 ofCave-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 ofglyphosate used to kill the cool-season grasses. Broadleafweeds were controlled with an application ofdicamba in the

summer of 1989. Following burning ofresidue in early spring 1990, reed canarygrass
was controlled with an application ofatrazine. 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 oftall 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 ofsome switchgrass treatments. Number ofswitchgrass baleswas 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 oftall fescue would be expected. Baleswere 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 ofthe 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 ofunweathered dry matter,recoverable weathered dry matter and total recovered dry matter as a percent ofthe 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 ofweathered hay and the probed composite and unweathered samples were weighed, dried at 60° C , weighed again for a measure ofdry 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 ofprediction 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 switchgrass) 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-PAC and SIPAC) was a nested split-split plot design with replications nested within site, surface (crushed rock versus sod) being the first split andwrap (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 ofvariance procedures were used to analyze data and statistical differences presumed when probability ofa 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 SIPAC 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. Genotypewas the main plot and plant population was the split plot. The late date ofplanting at SIP ACwas unavoidable because ofwet 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 10 4 and 2.58x 105 plants ha-l for sorghum and 8.6x 10 4 plants ha- 1 for corn. Rowwidth 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 SIPAC, respectively. Tiller count, height and lodging score measurements were taken at harvest. Datawere analyzed using analysis ofvariance procedures and significance considered when probabilitity ofa larger F statistic was less than 0.05.

RESULTS AND DISCUSSION
Objective 1

- Dry MatterLoss. Table 1 provides complete detail ofdry
matter losses. Storage oflarge 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 ofrecoverable unweathered and total dry mattervalues. The black plastic sleeve (ends open) and netting were superior to twine for the amount ofunweathered and total dry matter recovered as a percent of the original bale dry matter.

Amount ofweathered material associated with the black plastic sleeve storage treatment was not as great as other treatments, butwas greater than hypothesized. The moisture content ofthis weathered material was very high and was6

predominantly at the lower portion ofthe sleeved bale. From a practical standpoint, loss ofbales bound together by twine and stored on sod presented the greatest problem in terms ofgathering 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 ofthe bale and ground. A question that needs to be addressed is whether the presence ofweathered material is deleterious to the conversion ofthe feedstock to energy. Ifweathered material has undesirable characteristics for the conversion to energy, then method ofprotecting the feedstock will be potentially different than ifweathered material has a similar fuel value as unweathered material.

When comparing results ofstoring large round bales outside as compared to inside, total amount ofdry matter recovered is similar, except when bales are stored

on sod with twine. Cost ofstoring 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 ofstudy (August 1990-May 1991). While the two-way interaction ofwrap (twine versus net) and storage surface (sod versus rock) is not statistically significant (P 

### > 0.05), possibly because of a poor power oftest (one degree offreedom in the
numerator and fifteen in the denominator), the results suggest a measure ofpractical importance. Total recoverable amount ofswitchgrass is similar when netted bales

are stored on sod orrock (Table 2); however, there is a greater differential in favor ofthe 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.Table1.Percentageoriginaldrymatterofswitchgrassortallfescuelargeroundbalesrecoveredwhenstoredonsod,crushedrockorinsideandboundtogetherwithtwine,nettingorblackplasticsleeve.UnweatheredStorageSurfaceTwineNetSleeveSwitchgrassRecoverableWeatheredTwineNetSleeveTotalTwineNetSleeveUnweatheredTwineNetSleeveTallFescueRecoverableWeatheredTwineNetSleeveTotalTwineNetSleeve----------------------------------------------------------------------------------------------%ofOriginalDryMatter---------------------------------------------------------------Sod87.491.3 91.5Rock93.795.494.3Inside99.2Maineffectof"StorageSurface(Sodvs.Rock)"P<.01UnweatheredP=0.1RecoverableWeatheredP<.01Total4.35.13.02.8Maineffectof"GrassSpecies(Switchgrassvs.Tallfescue)"P<.01UnweatheredP<.01Total5.091.75.396.796.496.579.486.989.44.35.14.698.299.688.189.393.23.4 3.94.392.6Maineffectof"Wrap(Twinevs.Netvs.Sleeve)"P<.01Unweathered;BLSD(k=100,Papprox.=.05)=2.7P<.01Total;BLSD(k=100,Papprox.=.05)=2.483.792.091.593.2194.0197.5Table2.Percentageoriginaldrymatterofswitchgrasslargeroundbalesrecoveredwhenstoredonsodorcrushedrockandboundtogetherwithtwineornetting.TwineNetStorageSurfaceUnweatheredRecoverableWeatheredTotalUnweatheredRecoverableWeatheredTotal-----------------------------------------------------%ofOriginalDryMatter-----------------------------------------------------SodRock80.792.54.53.7Maineffectof"StorageSurface(Sodvs.Rock)"UnweatheredP=.03RecoverableWeatheredP=.03TotalP=.04Maineffectof'Wrap(Twinevs.Net)"UnweatheredTotalP=.04P=.0385.2%.292.395.54.42.696.798.1009

Material and labor costs expended to store the herbaceous feedstock and value ofthe feedstock will dictate what storage procedure is most economical. Current cost ofnetting is two to three times the needed amount oftwine used to bind large round bales. Price is dependent upon the size oflarge 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 tobe bound with netting and only $0.37 to be bound with twine. A factor in favor ofthe use ofnetting, however, is that capacity (number ofbales packaged perhour) 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 ofcrushed limestone laid 15-cm thick is $1.09 per m2

. Assuming that a large round bale requires 3.3 m2 ofsurface rock and that the rock will provide an effective surface for four years without further addition ofrock suggests that prorated cost will be $0.90 eachyear. Also, when rock is added again, it will be in a smaller amount than the amount initially needed.

ConstituentResults. No differences were apparent between the two locations (SIPAC and Feldun-P AC) for quality constituents ofswitchgrass. Quality analyses

on samples taken at the completion ofthe 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


# - 20 0**~** 

### 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 ofunweathered, 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 ofthe bales and do not include weathered material from the interface ofsoil and bale. With the exception ofNDF, composite samples had similar values to unweathered switchgrass (Figure 1). Composite samples ofswitchgrass 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 

### 60 0 :::::::!!
>-, 

### 40

..... 0



# - 20 0**~** 

### 0 75.8 75.7

1
NDF ADF 0 Aug-90 11 Dec-90 Iii May-91

1 1.1


### N Figure 2. Composition ofswitchgrass 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 ornet) 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,_:' 

### 40 0 < 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 ofswitchgrass hay stored on sod or crushed rock andbound with twine or netting. Values are means of2locations 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 ofswitchgrass hay stored on sod or crushed rock and bound with twine or netting. Values are means of2locations and 3 replicates. 

### P 

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

The study at SIP AC permitted comparison oftwo herbaceous biomass species, switchgrass and tall fescue, when stored as large round bales. As one would predict based upon previous comparisons ofswitchgrass 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 ofspecies and wrap type for NDF, ADF and N. Switchgrass composite samples had similar NDF, ADF and N values regardless ofwrap, whereas tall fescue boundwith 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 ofswitchgrass and tall fescue hay bound by netting, twine or plastic sleeve. Values are means of3 replicates, 3 sampling dates and 2 storage surfaces. 

### P < 0.01 for Species x Wrap interaction.



### 50

..._ 45.6 45.4 45.3 (l) 

# lo Net BD Sleeve! ........ 11 Twine __. 0 ::::::!: 2:" 40 a 

### 40


# - 0 N 

### w.: a <( 

### 30 Switchgrass Tall Fescue Figure 6. Acid detergent fiber composition ofswitchgrass and tall fescue haybound by netting, twine or plastic sleeve. Values are means of3 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 ofswitchgrass and tall fescue hay bound by netting, twine or plastic sleeve. Values are means of3 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 ofhay stored on sod, crushed rock and inside. Values are means of3 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 ofthe trial, indicating again that greatest concern is the interface ofthe bale surface and soil and not the portion ofthe 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 ofthe reduced yield at SIPACwas due to late planting14

because ofwet 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% ofthe total dry matter prodl!ction at TPAC and SIPAC, 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 l=flat, --Mgha

-- -m- 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 ofpopulation 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 oftotal recoverable dry matter as compared to storage on sod. Total recoverable dry matter was greatest with the use ofa 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 ofdry matter recovered suggests that inside storage is notjustified. 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 oftime similar to the studies conducted in Indiana. When considering the extra amount offeedstock not able to be picked up by mechanical means without aid ofmanual labor when large round bales are stored on sod with twine, this method ofstorage appears to be least satisfactory.

The importance storage surface andwrap has on feedstock constituency is overshadowed by their effects on dry matter losses. Greatest concern about deterioration offeedstock quality is not the surface ofthe 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 ofwrap, 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 andyield 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



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