Credit: Amy Yee
The resulting decline in cultivable land is a pressing concern for Bangladesh, one of the world’s most densely populated countries. (Imagine half the U.S. population living in a space about the size of Iowa.) Bangladesh’s population will likely increase from about 156 million today to around 250 million by 2050. Vertical gardens are one simple way that the rural poor can adapt to climate change and increase food supply using scarce resources. They could complement other, more sophisticated solutions, such as the cultivation of salt-tolerant rice and other hardy crops such as sunflowers.
“There is no country with such population density where natural resources are stretched to their very limits,” says Craig Meisner, south Asia regional director and country director for Bangladesh at WorldFish, an international nonprofit organization headquartered in Malaysia. WorldFish implemented the vertical gardens in southern Bangladesh, along with other means of coping with climate change. If adaptation “fails here, it will certainly fail in many other countries,” Meisner remarks. “However, if it succeeds here, it gives hope for the world’s future.”
Vertical gardens work because soil salinity actually fluctuates. Salinity decreases during Bangladesh’s monsoon season from roughly July to October, when about 1.5 meters of rain flushes and dilutes salt from soil. During the hot, dry months, however, the soil loses moisture and the salinity returns, explains Meisner, an agricultural scientist by background. So far, WorldFish is implementing vertical gardens only in Bangladesh, although examples of similar, local designs exist in other parts of the world. In theory, vertical gardens can work in salty soil in any area that gets heavy rainfall.
Working with local nonprofits WorldFish trained about 200 villagers in four districts in saline-affected areas of southwestern Bangladesh to make vertical gardens. Others not in the program have copied their neighbors’ designs after seeing how well they worked. WorldFish plans to expand the program to include 5,000 people over the next two years.
Growing the vertical gardens is a relatively straightforward process. Villagers harvest soil after the rains, around November, and use it later during planting season. They put the soil into containers and mix it with fertilizer made of dried water hyacinth, soil, coconut husks and cow manure. The containers range from plastic rice and concrete sacks to large, specially constructed “towers” made of simple plastic sheets encased by bamboo rings.
To prevent waterlogging, the containers are raised off the ground on bricks and filled with brick chips that improve water circulation and drainage. Small holes are cut into the sides where short-rooted vegetables such as Indian spinach and tomatoes can grow. Long-rooted vegetables such as gourds grow on top. These sacks can produce up to eight kilograms of vegetables in one season with an investment of 100 to 150 taka (about $1.30 to $2) per bag. The tower variety of container measures more than 1.2 meters across and can produce more than 100 kilograms of vegetables. One tower requires an investment of about 900 to 1,000 taka (around $11.50 to $13.00) to buy materials and seeds. WorldFish provides seeds and some materials to villagers in the first year.
stands in front of her vegetable garden, which is growing
out of sacks and onto her roof. Credit: Amy Yee
The result is a garden like the one that belongs to Shobitha Debna, a 35-year-old mother in Chandipur. The garden occupies just a corner of Debna’s dirt yard, yet it yields hundreds of kilograms of pumpkins, gourds, green beans, eggplants, red amaranth, beets, carrots, cauliflower, coriander, cabbage, green chili peppers and spinach each season. In addition the tin roof of Debna’s home harbors a lush tangle of leaves and vines that sprout fat bottle gourds. The vines grow from just a few large, plastic sacks that once held animal feed. Extra food like this goes a long way for the rural poor in Bangladesh, who eke out a living on a few dollars a day.
Debna says she used to grow just one or two kinds of vegetables but now her vertical garden yields a cornucopia that feeds her family. Finding enough fresh water for her garden can be a challenge, she admits. But so far that hasn’t stopped a bounty of vegetables from flourishing in soil that lay fallow not so long ago.
http://www.scientificamerican.com/article/vertical-gardens-beat-soil-made-salty-by-climate-change/
Amy Yee 