Hi
Eucalyptus belongs to the family Myrtaceae with about 300 species of the genus. The species is one of the fastest growing trees in the world and many species attain great heights. Eucalyptus amygdalin is the tallest known tree with specimens attaining a height of as much as 480 feet.
1.2 Basically, a native of Australia and Tasmania, Eucalyptus was introduced in India, by the British in 1843 in Nilgiri Hills as an experiment to find high yielding species for fuel and timber. It soon became a favoured species for the foresters/ commercial plantations, owing to its fast growth, non exacting, non- browseable and drought resistant nature and adaptability to a variety of agroclimatic conditions.
1.3 Eucalyptus is popularly known as gum tree, red iron tree, nilgiri or safeda. Many fast growing species suitable for commercial cultivation in India have been identified. Eucalyptus tereticornis and E. grandis are important commercial species with a clean straight bole and compact crown. Hybrid eucalyptus (combination to E. tereticornis and E. grandis /E. urphaylla/ E. camaldulensis) has shown greater vigour and drought and insect resistant characters in the field conditions and are preferred planting stock for commercial plantations.
Climate
Altitude range : 0 - 1000 m above sea level.
Mean annual rainfall : 500 - 3000 mm
Rainfall regime : summer, winter, bimodial: uniform
Dry season duration : 0 - 8 months
Mean annual temperature : 10 - 27 0C
Mean maximum temperature of hottest month : 22 - 42 0C
Mean maximum temperature of coldest month : -2 - 19 0C
Absolute minimum temperature : > -80 C ( data for upper limit NA)
Soil and Physiography
Soil texture : light, medium, heavy
Soil drainage : Free, seasonally waterlogged
Soil reaction : acidic, neutral
Special soil tolerances : saline
Soil types : alluvial soils, gravely soils, ferral soils, red soils, sandy soils
4.0 Nursery practices:
4.1 Eucalyptus can be easily propagated from seeds, as well as, through vegetative propagation by cuttings (clonal propagation). On an average, there are about 642,000 viable seeds per kilogram of seed and chaff mix. Dry seeds at 5-8% moisture content, can be stored in air tight containers under refrigerated conditions (3-5 0C) for more than 10 years without losing its viability.
4.2 Under nursery conditions, seeds are sown on raised beds under shade. Addition of mycorrhiza innoculum to the nursery soils by adding soil from natural eucalyptus forest is highly beneficial for establishment and growth of the plants. No pre-sowing treatment is required. Rapid and complete germination is achieved under moist, warm (25 - 35 0C) conditions in presence of light. Seedlings are pricked out and transferred to polybags at the second leaf -pair stage i.e. about 6 weeks from sowing. Seedlings are planted out in the field when they reach a height of about 25 cm i.e. about 3-5 months after sowing. This should coincide with the onset of monsoon season.
4.3 Plants at nursery stage are highly susceptible to damping off and other fungal diseases, which can be limited by strict attention to hygiene, reducing watering and shade and allowing good ventilation.
5.0 Cultivation practices
5.1 Eucalyptus, generally raised for industrial plantations - mainly pulpwood, firewood or poles, are maintained with a shorter rotation of 5-7 years. For commercial plantations, intensive site preparation by ploughing or deep ripping on compact sites, is beneficial. On wet sites moulding should be adopted to improve root aeration and provide well-drained condition that facilitate planting. Spacing adopted is 2m x 2m or 1.5 m x 1.5 m (high density plantations). In case, crops are cultivated between the rows (agroforestry), wider spacing of 4m x 2m ; 6m x 1.5m or 8m x 1m are recommended. Nursery raised seedlings/plantlets in polybags may be planted at the onset of monsoons, in pits of 45 cm x 45 cm x45 cm. Organic manure mixtures along with fertilizers containing 25g of NPK (3:2:1) and 50 g of phosphate should be applied in the planting pit at the time of planting. Protective irrigation is essential, in case of monsoon failure, in the first two years of plantation. Eucalyptus is intolerant to shade and does not compete well with grasses for water and nutrients, thus 2-3 hand weeding and soil working in the initial stages are essential.
5.2 Owing to its fast growth, Eucalyptus is a heavy feeder and requires supplements in form of organic and chemical fertilizers in successive years. Deficiency of Nitrogen in soils is a limiting factor for growth and can reduce the yield by 60%. For maintaining the soil fertility, it is advisable to raise Eucalyptus trees with legumes as an intercrop.
5.3 Harvesting is done by clear felling the stand in 6-7 year. Once the tree is felled, the stump throws many coppice shoots. These should be singled out to keep only one vigorous stem per stump, which will form the second crop. It is advisable to change the planting stock after the second harvest, as there is loss in vigour in coppice from the third coppice onwards.
Regards
Ashwini
