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Wright, N.A. 1990. Screening of herbaceous species for energy crops on wet soils in Ohio. p. 263-267. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

Screening of Herbaceous Species for Energy Crops on Wet Soils in Ohio*

N.A. Wright


  1. INTRODUCTION
  2. EXPERIMENTAL METHODS
  3. CROP ESTABLISHMENT
  4. YIELDS
    1. 1986
    2. 1987
    3. Harvest Frequency
  5. CONCLUSIONS
  6. REFERENCES
  7. Table 1
  8. Table 2
  9. Table 3

INTRODUCTION

Utilization of lignocellulosic crops for energy is rooted in the need for the United States to become less dependent on non-renewable sources of energy when such commodities become scarce. With a limited supply of fossil fuels, it becomes imperative to search for renewable energy sources. Such a source exists in grass and legume herbage for direct combustion or possible conversion to ethanol. This need was recognized by the U.S. Department of Energy (USDOE) with the beginning of the Herbaceous Energy Crops Program (HECP). The objective of the HECP is to screen herbaceous species under various crop production management practices on marginal land.

The Office of Technology Assessment (1980) stated in Energy from Biological Processes that grasses could contribute 29% of the potential bioenergy supply with the use of existing technology. They also suggested key research and development needs for utilization of energy crops. One such need was the selection of the most promising high yielding grasses and legumes, the first objective of the USDOE (1978) Fuels from Biomass Program for agricultural and nonwoody plants in 1978. Identification of potential species was initiated by Benson et al. (1978) but screening species on marginal land remains to be accomplished. For example, selection of high yielding grasses on very poorly drained land has not been explored. Marginal land utilization for energy, crops is in accordance with views that biomass species should be energy conserving by requiring little fertilizer, thriving on poor soil, and tolerating both wet and dry soils. The problem is that marginal soils often have many, production limitations. Growing cost effective energy crops on such soils will require exact matching of species, management levels, and soil type.

Bungay (1981) pointed out the costliness of getting high productivity on marginal land where ",water is the yield limiting factor. Crops selection must be geared also toward tolerance to wet, poorly drained soils. Of the nine possible forage grasses mentioned by Wedin and Helsel (1980) as suited for the north central region of the United States, only four have characteristics that show promise for maintaining prolonged productivity on wet, poorly drained soils. Birdsfoot trefoil (Lotus corniculatus L.) will grow on poorly drained, infertile soil (Seaney, 1973) and tall fescue (Festuca arundinacea Schreb.) shows good tolerance to poorly drained soils vet is also drought tolerant (Buckner and Cowan 1973). Probably the most flood tolerant grass currently in use is reed canarygrass (Phalaris arundinacea L.); tolerance to spring flooding of 49 or more days has been reported for mature plants (Martin and Heath 1973). Establishment practices for low fertility soils have been described by Kroth et al. (1976). Perennials with these characteristics are the most likely to survive on very poorly drained soils of low fertility. Fertilization along with weed control will be the most important and expensive management inputs for energy crop production. The objective of this project is to screen herbaceous species that appear promising for energy uses on soils which are marginal due to wetness.

EXPERIMENTAL METHODS

Three sites were selected to screen ten crops under two levels of weed control management and two fertility levels in a randomized complete block design with three replications of each treatment combination. Species being screened include alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), timothy, (Phleum pratense L.), tall fescue (Festuca arundinacea Schreb.), reed canarygrass (Phalaris arundinacea L.) switchgrass (Panicum virgatum L.), rye (Secale cereale L.), sorghum x sudangrass(Sorghum bicolor L. Moench),and two forage sorghum (Sorghum bicolor L. Moench) varieties. Rye and sorghum x sudangrass are used in a double cropping system. All three sites are located on Mollic Haplaquept silty clays with varying degrees of internal drainage, slope, and initial fertility. Site one contains subsurface drainage file, adequate soil pH, high fertility, and 0-2% slope. Site two has no tile, adequate soil pH and fertility, and 2-6% slope. Site three has no file, low, soil pH, low available phosphorus, and 0-2% slope. These three sites span the range from best to worst for a Toledo silty, clay of lacustrine origin. Management treatments for all sites include two weed control and two fertility levels. Level zero weed control involves no control measures. Level one weed control consists of chemical control used in normal production of these species. Level zero fertility represents adequate fertilizer additions to maintain initial soil nutrient levels and allowing nitrogen deficiency symptoms to develop just before harvest. Level one fertility represents an excess of fertilizer additions to eliminate fertility as a yield limiting factor during screening. All species at all sites are harvested once at the end of each growing season. An additional treatment at site one involves harvest of certain species twice each season.

CROP ESTABLISHMENT

The difficult nature of crop production on marginal soil was fully expressed during perennial establishment by conventional tillage. Three failed attempts at establishment of smooth bromegrass at all sites resulted in its elimination from the species fist. Tall fescue at site two and reed canarygrass at site three were deleted after three seeding failures. Tall fescue at site three was established on the third attempt. All sorghum species during each year exhibited the same problem but not to the extent of the perennials. The difficulty in establishment was due to soil crusting and later by winter freeze and thaw upheaval of young plants seeded during late summer. Soil crusting is one of the hazards of conventional tillage establishment of crops on silty clays. The necessity of pulverizing the soil for proper soil to seed contact always leaves the soil vulnerable to crusting. A no-till seeding study is underway to determine if these difficulties can be reduced by the presence of a residue mulch. Also, fall and spring seeding will be compared to determine if winter survival of seedlings can be increased by spring establishment.

YIELDS

1986

Yield differences in 1986 due to species were significant at all three sites (Table 1). The two leaders in dry matter production were forage sorghum at 14-22 t/ha and the rye and sorghum x sudangrass double crop system at 22-24 t/ha. Switchgrass was the third highest producer with only 4-6 t/ha. Increased fertilization resulted in overall yield increases at all sites. At site one, yield differences between the high and low fertility levels was solely a response to nitrogen for the grasses. The two legumes (alfalfa and birdsfoot trefoil) did not respond to nitrogen. A 2.0 t/ha forage sorghum yield response to higher fertility at site two was due to additions of nitrogen, phosphorus, and potassium. Lime, nitrogen, phosphorus, and potassium additions were responsible for 1.6-5.8 t/ha yield increases for timothy, switchgrass, forage sorghum, and rye-sorghum x sudangrass at site three. Weed control did not increase biomass yields in the first year with the exception of metolachlor to sorghum species where yield increases of 4.1-11.9 t/ha resulted.

1987

Dry matter yields for 1987 were higher for most of the perennials and similar for the annuals compared to 1986 (Table 2). Two forage sorghum cultivars, yielded 18-26 t/ha, and the rye-sorghum x sudangrass double crop system, yielded 19-24 t/ha. Significant yield responses to increased fertility were detected in the second year for most species at one or more sites. Benefits of weed control were more apparent in year two. For example, application of atrazine doubled yield of switchgrass from 3 to 6 t/ha.

Harvest Frequency

Table 3 is a breakdown of site one yields according to the number of cuttings removed per season in 1987. Both alfalfa and timothy under a one harvest per year plan suffered loss of dry matter when compared to the first of two harvests under the two cut system. Timothy dry matter losses were due to loss of the seed head upon drying and some lower leaf decay. Tall fescue, reed canarygrass, switchgrass, and birdsfoot trefoil all exhibited higher yields for the first harvest under both systems. These species were able to continue accumulation of dry matter even after seed maturity and did not lose as many leaves from decay as alfalfa and timothy. The only species to yield more under a one harvest system than the sum of two cuttings was birdsfoot trefoil. Whether increased yields from two harvests per season are enough to merit the expense of an extra trip over the field remains to be determined. Since forage quality in terms of livestock use is not a factor, it may be more economical to harvest only once at the end of a growing season.

CONCLUSIONS

Two years of data concerning the screening of herbaceous species for energy crops has led to some preliminary suggestions for the best species and management for lignocellulose production on wet, marginal land. Establishment has proven very difficult on the silty clay soils in this study. Problems of establishment must be considered when performing any economic analysis. A new study underway will compare conventional tillage to no-tillage establishment methods on the same soil type used for yield screening. No-till methods of seeding may increase the chance of successful establishment and reduce costs of production. Annual species showed a yield response to weed control additions. For all grass species, higher fertility resulted in higher yield. Additional yield was also achieved by harvesting twice each season compared to one harvest at the end of the growing season. An economic evaluation will determine if the additional dry matter gained from two harvests offsets the additional cost of the second trip over the field. These preliminary findings indicate that the most desirable perennials for energy crops on seasonally wet soils in Ohio would be reed canarygrass and birdsfoot trefoil, both yielding 6-7 t/ha. Annuals with the most promise include forage sorghum and a rye-sorghum sudangrass doublecropping system, yielding 18-24 t/ha.

REFERENCES


*This research is supported by the United States Department of Energy. Biofuels and Municipal Waste Technology Division Herbaceous Energy, Crops Program, through subcontract # 15X-27114V between Martin Marietta Energy Systems, Inc. and Geophyta.
Table 1. Yields under one harvest per season management in 1986.

Dry matter yield (t/ha)
Weed controlFertility level
Site and speciesOverallWithoutWith LowHigh
Site #1:
Alfalfa2.63.41.92.72.6
Timothy3.84.03.62.94.8
switchgrass5.35.05.64.75.8
Tall fescue5.15.25.04.35.9
Birdsfoot trefoil3.33.82.83.23.4
Reed canarygrass5.15.35.04.45.8
Forage sorghum-FS25E22.019.924.119.524.4
Rye + Sorghum x Sudan23.624.123.022.624.6
LSD (0.05)0.6- 1.0 -- 1.0 -
Site #2:
Alfalfa1.72.01.41.71.7
Timothy3.63.63.63.04.2
Switchgrass5.75.85.65.26.2
Birdsfoot trefoil2.63.12.02.22.9
Reed canarygrass5.04.85.24.45.7
Forage sorghum-FS25E16.214.517.915.217.2
Rye + Sorghum x Sudan22.221.922.521.522.8
LSD (0.05)1.1- 1.6 -- 1.6 -
Site #3:
Alfalfa2.02.31.62.02.0
Timothy3.23.23.32.44.1
Switchgrass3.73.44.12.94.5
Birdsfoot trefoil1.82.21.51.42.3
Forage sorghum-FS25E13.97.919.811.016.8
Rye + Sorghum x Sudan22.220.224.320.324.2
LSD (0.05)0.9- 1.3 -- 1.3 -


Table 2. Yields under one harvest per season management in 1987

Dry matter yield (t/ha)
Weed controlFertility level
Site and speciesOverallWithoutWith LowHigh
Site # 1:
Alfalfa 4.2 4.2 4.2 4.2 4.2
Timothy 4.7 5.1 4.4 4.3 5.2
Switchgrass 4.7 3.0 6.4 4.1 5.4
Tall fescue 5.1 4.7 5.4 4.4 5.7
Birdsfoot trefoil 6.7 6.6 6.7 7.0 6.4
Reed canarygrass 7.1 7.3 7.0 5.7 8.6
Forage sorghum-FS25E 17.9 15.5 20.2 15.6 20.1
Forage sorghum-S214 20.7 20.5 21.0 20.6 20.9
Rye + Sorghum x Sudan 24.3 24.2 24.4 20.8 27.8
LSD (0.05) 1.3 - 2.0 - - 2.0 -
Site #2:
Alfalfa 3.8 3.8 3.7 3.8 3.8
Timothy 3.8 4.2 3.5 3.2 4.5
Switchgrass 4.1 2.3 5.8 3.4 4.7
Birdsfoot trefoil 6.7 6.4 6.9 6.6 6.7
Reed canarygrass 6.0 5.9 6.2 5.4 6.6
Forage sorghum-FS25E 21.0 18.9 23.1 22.0 20.0
Forage sorghum-S214 20.2 19.8 20.5 18.6 21.8
Rye + Sorghum x Sudan 21.0 20.9 21.1 18.3 23.7
LSD (0.05) 1.6 - 1.2 - - 1.2 -
Site #3:
Alfalfa 3.8 3.7 3.9 3.8 3.9
Timothy 3.2 3.6 2.9 2.8 3.6
Switchgrass 3.0 1.9 4.1 2.5 3.5
Tall fescue 3.6 3.6 3.5 2.8 4.3
Birdsfoot trefoil 5.9 5.5 6.3 5.2 6.6
Forage sorghum-FS25E 17.1 15.3 18.8 19.0 15.0
Forage sorghum-S214 25.7 28.8 22.7 24.3 27.1
Rye + Sorghum x Sudan 19.0 18.1 19.9 17.5 20.5
LSD (0.05) 1.4 - 1.0 - - 1.0 -


Table 3. Yields separated by harvest frequency at site one in 1987.

Dry matter yield (t/ha)
Harvests/season
Species 1 2
Alfalfa 4.6
2.7
4.2 7.3
Timothy 5.7
1.5
4.7 7.2
Switchgrass 3.9
3.0
4.7 6.9
Tall fescue 4.7
3.0
5.1 7.7
Birdsfoot trefoil 4.3
2.0
6.7 6.3
Reed canarygrass 6.1
3.2
7.1 9.3
Rye 3.5 3.5
Sorghum x sudangrass 5.1
Sorghum x sudangrass 20.8 18.2
24.3 26.8
LSD (0.05)-Totals 1.3 1.3


Last update March 6, 1997 by aw