Proc., BIOENERGY '96 - The Seventh National Bioenergy Conference: Partnerships to Develop and Apply Biomass Technologies, September 15-20, 1996, Nashville, Tennessee.
The Minnesota Wood Energy Scale-Up Project planning began in late 1993. Cooperators include the WesMin Resource Conservation and Development Council, the U.S. Depart- ment of Energy's Biofuels Feedstock Development Program at Oak Ridge National Laboratory, the Electric Power Research Institute, the U.S. Forest Service at Rhinelander, Wisconsin, and the Minnesota Department of Natural Resources-Forestry. In spring 1994, Phase I, established 1,000 acres of trees. Phase II, documented here, includes plantings established on 870 acres by June 1995. The purpose is to track and monitor economic costs of planting, maintaining, and monitoring larger-scale commercial plantings. Accurate descriptive mapping of the soil classes and specific soil types, combined with specific site maps of hybrid poplar clones, and subsequent annual growth measurements during the first rotation will help researchers develop reliable site productivity functions. These functions will provide valuable information to support continued basic research on genetic enhancement and species screening to help assure producers reliable yields across representative soils in a production region. Major findings are per-farm costs of establishment and maintenance for establishment year, machinery complements used, and methods of management. In addition, an average cost of establishment across 1,000 and 2,000 acres is profiled. These costs assist potential growers and purchasers of this resource to determine ways supply and demand may be secured through developing markets. Average production costs are documented, and the management scenario is presented for establishment for Phase II planting. For Phase I documentation, refer to Downing, et al. (1996).
Keywords: hybrid poplar, production economics, wood energy
For 15 years, only smaller-scale research and experimental plantings of hybrid poplar have been used to screen for promising high-yielding candidate species. Currently, 1,870 acres of hybrid poplar trees have been planted on Conservation Reserve Program (CRP) land within a 50-mile radius of Alexandria, Minnesota. Phase I of the project involved planting 1,000 acres in 1994. Phase II began in 1995 and nearly 870 acres were planted. The project is beginning a third phase in 1996. At the end of 1995, 19 landowners had obtained 5-year extensions of their CRP contracts by planting hardwood trees. The CRP contracts will expire in 2001 when the plantings are 7 years old.
The purpose of this project is to track and document the economic costs of planting, maintaining, monitoring, and harvesting large-scale commercial agricultural plantings of hybrid poplar. It will also educate the public about short-rotation woody crops and be an important source of information for vendors, technical advisors, and others to learn about cultural practices that involve hybrid poplar or woody biomass production. The plantings are also an invaluable research facility for studying clonal performance, plantation growth and production, soil relations, wildlife use, and climatic effects, all at the larger scale.
Fall site preparation continued to be the primary concern for proper establishment of hybrid poplar cuttings. There are two methods for beginning fall site preparation. Ideally, operations should begin in June; however, late August should suffice. These can still ensure establishment success. First, producers may choose to cut the Conservation Reserve Program cover by mowing. After some regrowth, Round-Up is applied at the 1 to 1.5 quarts per acre rate. A second method simply involves spraying the fields with the same rate of Round-up without mowing.
One to 2 weeks following the herbicide application, moldboard plowing or either offset or plowing disks are used to break up the sod. Two or 3 days later, fields are worked very intensively with a tandem disk. Usually, based on weather or other operational delays, tandem disking operations could continue into early or mid-September.
By mid-October, the following operations should take place to complete proper fall site preparation. The field must be smoothed and groomed before marking the field for spring planting. This will ensure demonstrative markings to last through snow cover, and spring thawing. Using a field cultivator or a smoothing harrow will ready the field for marking operations. After marking, and preferably before the ground freezes, a fall Oust application is desirable. In addition, if erosion is considered to be a problem, producers can sow 0.5 bu of oats per acre to prevent erosion. Oats are not winter hardy in this location. Rye is not considered a desirable cover crop because it will begin to grow again in the spring.
In spring, fields treated with Oust in the fall may simply be planted. Sites not sprayed with Oust may need field cultivation and harrowing. Following cultivation and harvesting, fields need to be marked for planting so trees can be planted accurately. An Oust application is then necessary followed by a 10 to 14 day waiting period before planting.
Table 1 outlines 1994 establishment average cost per acre (Downing et al. 1996). Table 2 contains the 1995 establishment costs. The 1996 report on Phase III (commencing late 1995) of the project will document the cost of labor and time spent performing different establishment and maintenance functions. A more comprehensive and detailed machinery complement documentation will be forthcoming.
| Table 1. 1994 Hybrid Poplar Average Per-Acre Establishment Cost (13 sites, 1,000 acres total). | |
| Operation | 1994 $/acre |
| offset disk and plow | 15.00 |
| tandem disk | 8.00 |
| disk/chisel | 15.00 |
| Round- up application | 19.00 |
| tandem disk cultivate/harrow | 8.00 |
| burn down and herbicide as needed | 10.00 |
| apply Linuron/Lorox | 34.00 |
| tree stock/ship/store | 73.00 |
| planting cost (8X8) spacing | 49.00 |
| first cultivation | 10.00 |
| second cultivation | 10.00 |
| third cultivation | 10.00 |
| herbicide application | 15.00 |
| AVERAGE COST PER ACRE | 276.00 |
During the 1994 establishment period, many trees were machine planted. As a result, some placement of cuttings was not accurate. Cuttings were too deep, too shallow, or not "firmed" into the soil. Air spaces, for example, cause desiccation of cuttings as a result.
Fields alternatively planted by hand, using a planting hook, were planted accurately, which afforded cross-cultivation for better weed control. To ensure proper planting, several supervisory personnel count cuttings planted, randomly check depth of planting, and spot check cutting planting direction. Although cuttings are commonly painted on the "up" end, additional quality control checks proved invaluable. Overall survivability increases as a result of hand planting, and the cost of planting only increases marginally.
| Table 2. 1995 Hybrid Poplar Average Per-Acre Establishment Cost (5 sites, 870 acres total). | |
| Operation | 1995 $/acre |
| fall site preparation complete | 35.00 |
| Round-up application | 18.00 |
| tandem disk cultivate/harrow | 10.00 |
| apply herbicide | 20.00 |
| tree stock/ship/store/soak | 82.00 |
| planting cost (8 x 8) | 38.00 |
| 4 cultivations | 40.00 |
| AVERAGE COST PER ACRE | 243.00 |
After planting, two field supervisors are assigned each of the 18 planted sites or a total of 1,870 acres. They cruise every field once each week to check for general condition, extent and type of weed growth, obvious pest problems, disease, and moisture levels. In this way, fields can be monitored to prevent problems from getting ahead of the landowner, cultivator or herbicide applicators. A Forest Service advisor also makes a monthly tour through all the fields. Fields notes taken assist all decision-makers in delegation of tasks to be performed. These field notes will also assist in determining the reasons why relative yields differ across different soils with different clones 2 or 3 years after establishment.
Rainfall in 1995 was variable within fields and across fields. Although fall and spring site preparation were completed, early initial after-planting site maintenance was difficult. Some maintenance was delayed in the western and southern areas of the region as a result.
Some interplanting was completed on a few Phase II sites in the spring of 1996. One site will be replanted because the landowner used inappropriate tillage equipment for cultiva- tion. Oust was applied successfully across all sites prior to trees breaking dormancy. This application will assist weed control throughout the growing season.
Continued research on weed control is critical to the success of planting establishment. Research on a plastic mulch test will provide economic and production data about the benefits and costs of nonchemical weed control. Herbicide trials continue across a wide range of clones and chemicals. Many herbicides are not labeled for use on hybrid poplar. Resistance to herbicide damage as a result of breeding efforts continues. For example, the Oust label was re-issued based on work completed on the sites in 1994 and 1995.
Plantings established during the 1996 planting season on CRP land along the Minnesota River Basin southeast of Alexandria will provide initial data about economic and environmental effects as a result of growing larger scale agricultural plots.
The average cost of establishment in 1995 was $243 per acre. This is a reduction of $33 over 1994 establishment costs of $276. There are several reasons for this. The cost of tree planting was reduced in 1995 over 1994 costs saving $11. This was a result of hiring different tree planting crews and a change of oversight management during planting operations. There were no fields burned in 1995 which saved an additional $10. No Linuron was applied in 1995, which saved an additional $35.
Several per acre average costs did increase. The average number of cultivations in the first year increased to four from three. This resulted in an increase of $10 per acre aver- age cost. Additional herbicide application increased across all sites by an average of $5 per acre. This was true even with a reduction in purchase price of Oust to producers due to relabeling. Cost of handling trees increased $10 because the soaking operation was included in a category called tree stock, ship, store and soak rather than including soaking in the cost of planting. Overall, the net reduction was $33 per acre average.
Four major accomplishments highlight 1995 over 1994 production. Much better site preparation was completed across all sites. All of the sites were hand planted instead of machine planted. Planting was much more uniform as a result of hand planting, and coordination of crews and soaking of cuttings was better organized. Finally, written specification of planting material was provided to all nursery stock suppliers. Additional gains in understanding are expected to made as the project continues.