Nitrogen fixing trees are unique natural gifts that can solve the problem of nitrogen deficiency, one of the major problems of present world’s agriculture, without any potential ecological or environmental hazard. Apart from nitrogen addition to the soil, they are also capable of improving the quality of soils to a great extent; e.g. they can turn a disturbed soil into a good one. To facilitate their use in all types of environments, nature has a wide range of nitrogen fixing varieties those can grow even in the most unfavourable climatic conditions including extremely low temperatures. Here are three nitrogen fixing trees to be introduced in snowy areas which are tolerant to very low temperatures and can withstand a low temperature of even -40°C.
Caragana arborescens
Caragana arborescens is a medium to fast growing perennial shrub or small tree. These Deciduous shrubs can grow to 6m by 4m. They are good nitrogen fixers and very good soil companions in snowy regions as they can tolerate extremely low temperatures.
Common names: Siberian pea tree, Ross caragana, pea-tree.
Family: Fabaceae
Low temperature tolerance: Withstand even -40° C temperature.
Nitrogen Fixation: 85-160lbs/acre
Hardiness Zone: 2-7
Native Range: A native species to Siberia, some parts of China and Mongolia.
Leaf: 3-5 inches long alternate leaves. Each leaf contains 8-12 oval leaflets.
Flower: Flowers are small, yellow in color, fragrant and generally bloom in May or June.
Fruit: Pod fruits that contain many edible seeds inside. Fruits ripen in July.
Why it is a great soil companion in Snowy regions: This species is capable of growing in snowy regions and fixing nitrogen for its own nutrition as well as for neighboring plants. They are very good in soil reclamation, erosion control and drought tolerance. They also provide windbreak, wildlife food, wildlife shelter, fodder, medicines, fiber, dye etc.
Elaeagnus angustfolia
Elaeagnus angustfolia is thorny shrub or small tree which is deciduous and grows to 7m by 7m at a medium growth rate. This species is hardy to zone 2 and can withstand a minimum temperature of -40 C; therefore an excellent species for nitrogen fixation and soil reclamation in snowy areas.
Common names: Russian olive, Oleaster, Silver berry, Persian olive, wild olive.
Family: Elaeagnaceae
Low temperature tolerance: Withstand even -40° C temperature.
Nitrogen Fixation: 160 lbs/acre or even more.
Hardiness Zone: 2-7
Native Range: Europe to West Asia.
Leaf: 1-4 inches long simple leaves having silver scales on both sides.
Flower: Outside color of the flowers is silver while inside is yellow. The sweetly fragrant flowers bloom in May to June.
Fruit: The 1cm long fruits are yellow in color and covered by densely silver scales. Each fruit contain one large seed within.
Why it is a great soil companion in Snowy regions: This species is very good in tolerating very low temperature of snowy regions and fixing nitrogen to the soil for its own use as well as for surrounding plants. It produces edible fruit that can be consumed raw or cooked. This tree provides seed oil, leaves and flowers to produce medicines. This tree can work as a hedge in exposed positions. It also provides fodder, quality hard and fine-grained wood, excellent fuel etc. This species must be used wisely with caution as it may become invasive if used unwisely.
Elaeagnus commutate
Elaeagnus commutata plants are deciduous shrubs or small trees that grow to 4m or 12ft in height and 2m or 6ft in width. They are rapid-growing, long-lived and very hardy for cold climates. They are also resistant to drought, diseases and insect problems. Due to their nitrogen fixing capacity and many other beneficial characteristics to the soil they are recommended as a great soil companion in snowy regions.
Common names: Silverberry, Wolf-willow, American silverberry, Wild olive.
Family: Elaeagnaceae
Low temperature tolerance: Withstand even -40° C temperature.
Nitrogen Fixation: Medium nitrogen fixer; estimated yield- 85-160lbs/acre
Hardiness Zone: Hardy to zone 2
Native Range: A native variety to North America (Quebec to Alaska and south to Utah), South Dakota and Minnesota.
Leaf: The leaves are 2-7 cm long, broad lanceolate, silvery on both sides with white scales.
Flower: The yellow colored showy flowers are fragrant, bloom usually in June to July.
Fruit: 9-12 mm long fruits are ovoid drupes. The fruits are edible with high quantity of vitamins and minerals.
Why it is a great soil companion in Snowy regions: This extremely cold tolerant variety is an excellent nitrogen fixer and soil restorer. Apart from adding nitrogen to the soil, it is useful in many other ways such as- it gives edible fruits and seeds, its fruits have medicinal value and are effective to reduce the incidence of cancer, it can be used as hedge, it also provides beads, fibre etc.
Russian Olive *is* a good nitrogen fixing tree. However, it is also considered an invasive species in much of the western US. Be cautious when introducing it into a new region as it might be aggressive or illegal to plant.