Intercropping with Paulownia - the "Wonder Tree"

Tags: paulownia, intercropping, wheat, corn, rice, sweet potatoes, timber, green fertilizer, fodderIntroduction

In many Third World countries, the depletion of native forests coupled with the increased demand for timber and fuel is creating serious environmental, economic and social problems. One strategy that deals with this situation is to encourage rural people to integrate trees within existing farming systems. 

In China, the 11 species of Paulownia have been used with great success in agroforestry programs. Some two million hectares of farmland have been planted with Paulownia, helping to alleviate the chronic shortage of timber, fuelwood, and animal fodder, and at the same time increasing agricultural production and improving soil conservation. The lessons learned concerning the successful use of Paulownia in China can benefit many other countries facing similar problems of competing priorities between agriculture and wood production. 

Scientists at the Chinese Academy of Forestry (CAF) have been studying Paulownia since 1959, and have developed and distributed several improved varieties to farmers and organizations in China and in other countries. IDRC began financing CAF research back in 1982. Then, with Centre funding in 1991, the International Farm Forestry Training Centre (INFORTRACE) was established as part of the CAF as a centre of excellence for agroforestry and integrated rural development. Over the years, China has become a global leader in agroforestry research. The benefits of Paulownia trees are numerous: 

• They are adaptable. They grow on flat or mountainous land, in various types of soil, including rich humus soil in temperate areas, dry poor soil, rich forest soil, and light clay soil in the subtropics, laterite soil in the tropics, and dry steppes. In general, Paulownia is suitable for planting in deep soil that is loose, well-aerated, and fed by underground water at a level below two meters;


• Paulownia also adapts to a variety of climates, from warm and temperate to tropical, and can even withstand temperatures as low as -20° C (different species vary in their resistance to the cold). The mean annual temperature for Paulownia is 13-25° C. Precipitation needs also vary greatly, from as low as 500 mm to a maximum of 2 000 or 3 000 mm annually;


• They grow extremely quickly (average growth of two meters per year in height and 4-5 cm around);


• They have a deep root system that, for the most part, does not compete with the roots of crops;


• Their branches and leaves are sparse, allowing plenty of light to come through;


• Intercropping with Paulownia can improve the microclimate by reducing the effects of drying winds (wind speed can be reduced by 20-50% on average) and increasing air moisture, which considerably increases yields of some crops such as winter wheat and millet (provided that suitable crop density is maintained);


• Paulownia produces a beautiful, light wood, which is useful for furniture, plywood, musical instruments, and handicrafts; its sale can considerably increase the income of rural people;


• Its branches can be used for fuelwood (a 10-year-old tree produces 100 kg of dry branches);


• The leaves are rich in protein (16.2%), carbohydrates (9.44%), and minerals, making them ideal for animal fodder and green fertilizer (a 10-year-old tree produces 80 kg of dry leaves per year);


• The leaves, flowers, and bark have medicinal properties. 

If the trees are used primarily to improve agricultural production, approximately 40 to 67 trees are planted per hectare. Intercropping with Paulownia will increase yields of wheat, corn, cotton, and millet. Crops such as sesame and sweet potato are not suitable for this method and their yields may actually decrease. If 50 trees are planted per hectare, they will produce 20-30 cubic meters of timber per hectare in 10 years, a source of important extra income to farmers. 

Paulownia trees can also be planted primarily for timber production, with crops as a secondary activity. In such case, 200 trees are planted per hectare. An initial yield of two crops per year is reduced after four years to one crop per year, but can still amount to some 37.5 tonnes per hectare over 10 years. From 90 to 110 cubic meters of timber per hectare can be produced after 10 years. 

Impact

• Training - The International Farm Forestry Training Centre has trained more than 240 scientists, land-use managers, and policy makers from a variety of countries in Asia, Africa, and the Americas, in Paulownia intercropping since 1991. Training efforts continue with a workshop scheduled for September 1998 on "Genetic Resources and Cultivation of Paulownia". 

• Further research based on successes - Building on a long history of agroforestry practice and Paulownia research in China, the Chinese Academy of Forestry continues its investigation into the taxonomy and distribution, tree improvement and selection, cultivation and afforestation, timber properties, pest control, and molecular biology of Paulownia. Some 10 superior clones have been selected and distributed on a large scale throughout the country. Professor Zhu's farm forestry project has resulted in the planting of 900 000 hectares of land with Paulownia, bamboo, Chinese fir, and other tree varieties, boosting annual rural earning by about US $20 million as of 1995.

Prerequisites

Access to seedlings or root cuttings of appropriate Paulownia species for local conditions; training in planting and managing the trees and intercropping techniques. The International Farm Forest Training Centre of the Chinese Academy of Forestry provides training courses for farmers, researchers, technicians, and extension workers. 

Potential users

Farmers around the world could benefit from intercropping with Paulownia, especially in areas with timber, fuelwood, and fodder shortages. Paulownia seeds have been introduced in more than 30 countries in Africa, the Americas, Asia, Australia, and Europe. Considerable success has been achieved in Australia, India, and Pakistan. 

Cost and availability

Seeds of different Paulownia species are available from the New Era Farms (see below).

Contact

Paulownia Now

www.paulownianow.org

Resources

From the Chinese Academy of Forestry (CAF): 

A 27-minute film in English entitled Paulownia in China has been produced by the Chinese Agricultural Studio.

Agroforestry Systems in China. 1991. Chinese Academy of Forestry and IDRC. 216 pp. Models, development, research, and experiences of agroforestry in tropical, subtropical, temperate, and semi-arid regions in China. 

From the IDRC Web site:

Agroforestry Systems in China. 1991. Published jointly by the Chinese Academy of Forestry and the International Development Research Centre. Available at: http://archive.idrc.ca/library/document/090916/ 

Paulownia in China: Cultivation and Utilization. 1986.  Chinese Academy of Forestry staff, Asian Network for Biological Sciences and IDRC. 65 pp. Available at: http://archive.idrc.ca/library/document/071235/071235a.htm 

Xiong Yao Guo.1990. Final Technical Report of Paulownia Project (Phase II).   The Chinese Academy of Forestry. Available at: http://archive.idrc.ca/library/document/086352/086352a.htm 

Zhu Zhaohua.1995. (http://archive.idrc.ca/books/738/zhu.html) From, In Person: Portraits of researchers in Africa, Asia, and the Americas. IDRC. 190 pp. ISBN 0-88936-738-8. 

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