Modern fertilizers improve plant growth with less nitrogen leached into the environment.

Modern fertilizers improve plant growth with less nitrogen leached into the environment.

Traditional fertilizers contain inorganic nitrate or ammonia ions as a source of the nitrogen that all plants require for healthy growth. But the nitrate ions’ negative charge allows them to leach into the soil, eventually reaching local streams and lakes. The rapid expansion of oxygen-consuming organisms can eventually lead to an ecosystem dominated by anaerobic bacteria that are deadly to both flora and fauna.

Together with three Swedish forestry companies, the biotechnology company SweTree Technologies has developed a new type of plant nutrient that releases significantly less nitrogen into the environment while actually improving plant morphology. Partners in the project are Holmen Skog, Sveaskog and Bergvik Skog.

The venture’s genesis came from research by Professor Torgny Näslund at the Swedish University of Agricultural Sciences looking at the direct uptake of organic materials by plants. Näslund discovered that plants directly absorb nitrogen-rich substances such as the amino acid arginine. Further research, including a doctoral thesis, shed more light on the role of arginine as a plant fertilizer. Holmen Skog initiated a commercial project aimed at confirming the results.

Holmen Skog sold a patent for the new fertilizer to SweTree Technologies in 2005. Together with its partners, SweTree developed a new product which is now marketed under the name arGrow®.

Bound nitrogen

Arginine is a basic amino acid that contains high levels of nitrogen. Part of the molecule is positively charged, which causes the substance to bind tightly to the soil, reducing run-off from rainfall or artificial irrigation. This in turn reduces over-fertilization of waterways.

Another positive effect from the new nutrient involves changes in plant morphology, specifically increases in the diameter of roots. This helps to achieve optimal nitrogen levels for plant growth as well as encouraging development of “fine roots” that aid in the uptake of water and nutrients. Plants nourished with arginine are more drought-tolerant and grow faster than those on traditional fertilizers. This increase in growth lasts for several years; the longest-running tests show that the effects persist for at least seven years.

The trials also show that young plants fertilized with arginine are better able to survive extreme weather conditions and parasite infestation during their most vulnerable years—an important consideration in commercial forestry since more seedlings are able to reach adulthood and yields are improved.

Millions of plants tested

The first Swedish tests with arginine took place at Holmen’s nursery in Gideå. By 2008, the nursery was fertilizing more than 9 million plants with arginine—nearly half of its total production. The nutrient is now under evaluation by four of the five largest forest owners in Sweden, and at least one company is using arginine fertilizer commercially.

SweTree has chosen to focus on potential applications of biotechnology in the forestry sector. The business concept is to develop trees that are better able to survive, grow faster and produce more high-quality timber. The company’s agenda also encompasses development of new technologies for modification of wood fibers. In addition to the nutrient arGrow®, SweTree’s portfolio includes several other projects:

  • Utilization of somatic embryogenesis to produce fast-growing fir trees. This project aims to identify individual trees that best meet commercial requirements and then use cells from those trees to make copies. This is essentially traditional plant breeding, a technique that has been used successfully in the United States to produce fast-growing loblolly pines (Pinus taeda). SweTree expects to have a production process online in 2012.
  • Production of “tailor-made” trees for the forest industry by analyzing which genes result in particular traits. For example, pulp and paper manufacturers may be interested in certain characteristics, while others are in demand for energy production. Both industries are particularly interested in increasing biomass.
  • The use of trees in the genus Populus (which includes poplar, aspen, and cottonwood) is being tested for fiber and energy production in the Baltic Sea region. Early results show promising growth rates, indicating that these species may well prove to be excellent alternatives in production of biomass for a future energy mix with a higher share of renewable raw materials.
  • Several projects are studying the potential for fiber modification. Six technology platforms are under development with the aim of adjusting cellulose fibers so that can be more widely used as replacements for oil-based polymers.
Article published in August 2009