Restoration of natural habitats and natural landscaping are important parts of nearly all natural resource development plans, road building projects, mine reclamation and oil field restorations. Because of this, there is a high demand for native plant materials. Agencies and companies charged with restoring previously developed lands must go outside Alaska for much of the needed plant materials. However, there are advantages to using native plants over sources from outside the area. First, using native species enables restoration to mesh with the natural vegetation, which is beneficial both aesthetically and ecologically. Second, native Alaskan species will survive our climate and conditions better than non-native or ornamental species.
There are enterprises producing native plants and seeds in Alaska, but they focus on replenishing the south-central and southeast part of the state. ABR Inc., an environmental consulting firm in Fairbanks, researches the effectiveness of using native legumes for revegetating gravel oil pads. Most revegetation is done using a mixture of native grass cultivars because they are readily available and relatively inexpensive. For long-term productivity and sustainability, however, it is critical to include nitrogen-fixing species such as legumes.
Because there are no commercial producers of native legumes, ABR Inc. has hand-collected seeds on-site at the approximate cost of $1000/lb. An agricultural operation in the Kenai Peninsula has estimated that these seeds can be produced for $100 to $300/lb. There are approximately 7,000 acres of gravel roads and pads on the North Slope oil fields that will need to be reclaimed after decommissioning. To do this, approximately 2½ lb/acre of seed is needed, costing $2 million to $5.5 million. Having the seed-producing capabilities in place for oil field restoration would open other markets, such as landscape companies, the State Department of Transportation, Army Corps of Engineers and Natural Resource Conservation Service. Presently, they use non-Alaskan sources for plant materials.
SARE funding granted in 2000 to Rosie Creek Farm gave us important results for solving propagation problems and developing a protocol for germination requirements and container production. Seeds from each legume species were given three seed treatments (acid scarification, physical abrasion and control) and then germinated in two different germination media. Data were collected on germination success determined by survival after 20 days.
Our results after one year of growth in the field showed differential survival and growth rates by species or in different areas of the farm (well drained vs. more saturated conditions). Based on these observations, it was our hypothesis that optimal growth of these species will benefit from both better drainage than our current soil (almost pure glacial silt) and using a low N fertilizer to cut down on competition from weeds and reduce insect outbreaks.
We realize we needed a longer-term project to determine the time (in years) necessary for maximum production. We needed further research specifically geared to field production of these species.
1) Assess methods to improve field survival
2) Evaluate cost effectiveness of varying soil pH and amendments
3) Determine seed production rates per plant and per unit area
4) Assess insect infestation problems
5) Evaluate extent of weed problems and weed control methods
6) Determine costs of small-scale production and develop cost estimates for larger scale production
Seeds were started in the spring of 2000. The plants used are slow growing and weed competition is intense, so the seedlings were transplanted into 2.75” containers and allowed to grow for a season before setting the plants out in the field. Four hundred seedlings of each species (Hedysarum mackenzii, Astragalus alpinis, Hedysarum alpines, Oxytropis deflexa, O. campestris and O. viscid) were grown in containers and over-wintered. The following spring (2001) beds were set and fertilized. Beds were 3 feet wide and 100 feet long. There were two rows to a bed with 12 inches between plants. Plants were fertilized with fishbone meal at 1000 lbs. per acre. Greensand was also added to the beds at 1000 lbs. per acre to add potassium and trace elements. Plants were hand weeded through the summer and evaluated prior to counting leaflets and flowers.
The following spring and summer (2002) beds were weeded, evaluated for growth and seeds were harvested in August. Seeds were collected by hand into paper bags, dried, cleaned, and weighed at the University of Alaska research farm.
RESULTS AND DISCUSSION
The plants were transferred to the field in 2001 and evaluation of flowering and field production and field monitoring began in 2002. Early results were encouraging. Oxytropis deflexa and Astragalus alpine greened up quickly and were soon in flower. O. campestris, O. maydelliana and O. viscid greened up slower but still flowered. Hedysarum alpinum did not survive well after planting in 2001 and those that did survive the winter grew slowly if at all.
Although some plants grew fast, they were still relatively small after two growing seasons (2-5 cm tall) and competition with weeds soon became an important factor. We began hand weeding the plot almost immediately (mid-May) and were soon spending 30 person-hours per week weeding the ¼ acre plot. When resources were taken away from the experimental plot, weeds took over rapidly. Because of the intense competition from weeds and limited person-hours to concentrate on the project, no data were collected on field growth rates of flowering.
Despite the weeds, we were able to harvest seeds from all the species except H. alpinum. O. deflexa produced particularly well, yielding 200g of seed from the 200 original plants. Given the space allotted to the plants O. viscid and O. campestris produced roughly 10% the rate of O. deflexa yielding 20 and 22 grams respectively. Although Astragalus alpines grew rapidly at first, it was soon weakened by disease and almost all the plants died by mid-summer. Hedysarum alpinum did not compete well with the weeds or grow well in the silt soils, those that did survive did not flower. All species were infested by aphids.
Some plants, particularly O. viscida, flowered a second time after seeds were harvested. Though hand weeding continued, by August the experimental plot was so engulfed that it was obvious the project was failing. As soon as green-up started in 2003, the plants that survived the aphids and weeds were less vigorous and we decided to till in the plot.
We started 4000 plants in the spring of 2002 with the purpose of starting the main experimental plot in 2003. By the end of 2002 and early 2003, we needed to abandon the project. We had limited field space on the farm and needed the space for cash crops. The amount of labor it took for weeding the experimental plants took resources away from crops that were making money for the farm.
BENEFITS AND IMPACTS ON AGRICULTURE
We started the experiment thinking that since these were native species, they would require less care to grow. This was far from the case. Our soil is pure silt-to-silt loam and most of these species are adapted to well-drained sands and gravels often found along rivers.
Despite the problems we encountered with this project, the results on seeds collected, particularly with O. deflexa, were encouraging. We harvested seeds of O. deflexa at the rate of 31 lbs/acre. The cost to produce the seeds was exaggerated because it was a pioneering effort. In a production setting where the plants would be another crop in a farm plan, it would be less expensive.
RECOMMENDATIONS AND CONCLUSIONS
Growing these plants and harvesting seed at a profit is possible for the right grower and situation. The fact that we were able to harvest as many seeds as we did from O. deflexa in less than favorable growing conditions was encouraging. One should start with a more sandy or gravelly soil and then plant through a wood barrier. Also, consider growing plants in containers and then planting them directly in their intended setting. The plants we started in containers in 2002 for the main body of this experiment were donated to ABR in 2003. They planted them directly in the ground at their restoration sites, and from incidental reports, they were growing well in 2006. Container growing is much easier in the short term since it is simple to provide the right growing medium in small containers rather than recreate it in a farm setting.
This project’s findings have been shared at the following venues: the Statewide sustainable agriculture newsletter published at the University of Alaska Cooperative extension in Fairbanks, the Alaska Greenhouse and Nursery conference in 2003, the Alaska Native Plant Conference in 2002 and 2004, farm tours from 2001 to 2005, and contact with other farmers at the Alaska Sustainable Agriculture conference in 2005 and 2006.