Written by Doug Crouch
With the constant downpours that never cease to amaze us how loud the pings can be on the tin roofs, the rains of the tropics are both a blessing and curse. The rains are one of the main leaching forces that limit the tropical soils depth and subsequent fertility. They are very seasonal in most places and form the moisture that creates the abundant soil and atmospheric humidity for constant microbial breakdown of organic material. With these rains, the intense tropical sun, intense microbial breakdown, and swift winds from times, the humus content and fertility is limited in the tropics. On this page and the others called soil building techniques we will pay particular attention to a combination of techniques that can bring fertility to the soil. Without it, they quickly become exhausted and the collapse of the soils brings infertility, disease, and insects. This is the common reason for so much slash and burn agriculture in the tropics and other natural capital degrading agricultural practices such as the use of synthetic fertilizer and pesticides. Thus we must use techniques for water harvesting to lessen this erosive force. Earthworks are the first technique that Bill Mollison laid out in his tropical chapter of the Designer’s Manual that forms the skeleton of this “blook”. They have been employed for millennia to deal with this flow and can be seen in the following major forms in the tropics:
- Pond Edge Manipulation
- Sponges including Banana Circles
Creating spaces for waters infiltration is our main objective for creating swales. These ditches and mounds that lie on contour, aid in slowing, spreading, and sinking water. The use of contour asks a force to conserve water rather than the traditional method of sending water away. The infiltration of water into the ground is extremely important for building soil in the tropics because without it the erosion picks up our hard work of building soil. Remember to start at the top of your hillside and in the tropics we often need successive earthworks to deal with the tremendous potential of the water. They are spaced much closer together than ones in the drylands and often are large in size.
Trees should always accompany the earthwork to stabilize the soil and cycle the energy of the infiltrating water. Plants can be staked in space and time with the use of biological resources conveniently used to build natural capital. Swales can be created by hand or with machines and can connect to other earthworks such as ponds.
Terracing has long been used by humans to create access and planting space on hillsides that would normally be nearly impossible to cultivate. The technique requires a skill we often lack these days which is to build with dry stacked stones. Some of the existing terraces of complete territories like those in the Minho Valley in the North of Portugal should be revered just as much as any modern skyscraper or famous building of antiquity such as the Parthenon. The leveling process requires a good eye and muscles but is not impossible. It just takes time and the skill to stack stones with no mortar hence our needs for rural skills centers as the traditional fails to be passed on. The walls continue to deteriorate as well and the work of centuries is failing in places like Northern Italy. This truly is a loss of natural capital that our European forefathers created but in one generation has been lost.
The tradition of terracing hillsides to create level areas for cultivating rice is an impressive use of contour. With waters undeniable ability to show this facet of nature, contoured hillsides have long been used to produce staple foods. Here the photo shows different times of planting and draining with the red earth exposed while others are flooded and others have the green growth of rice.
Pond Edge Manipulation
After a pond is constructed one can also crenelate the edges of the pond for increased interaction between land and water. This edge is abundant and allows for added growth of wetlands plants that can be cycled to the surrounding earth. Lowland soil rich in organic material was also cycled into nearby beds.
Sponges facilitate the development of nuclei to merge in small scale intensive systems as system succession progresses. The system uses ditches and mounds to create a diverse space thats edge creates numerous niches and
subsequent functions. The depression acts as a space for the never ending flow of organic material that stems from life in the humid tropics. It creates a safe haven for the organic material that is often discarded or burned in accordance with long standing traditions about cleanly spot around the house. The copious amounts of tropical food waste may also be processed by the sponge as the outflow is compounded by subsistent agriculture movement. The depression hold constant water and fertility aiding the associated plant tapping downward from the perched bed space. The cycle is filled completely with good design.
The sponges can also be a greywater system in the humid tropics. Often piping simply is out the back of the house and not necessarily designed for its maximum use. This can be altered with some extra piping and proper placement of the sponge. The carbon material will happily feed on the soaps and organic material while the plants will also never get dry. Reportedly in reforestation in the drier regions of Haiti this technique has worked great fro establishing banana’s. This is a great testament since that area of Haiti has no soil and very little rainwater distributed evenly over the year.
Mollison, B. (1981) Permaculture: A Designers Manual. Sisters Creek, Tasmania, Australia. Tagari.
Written by Doug Crouch
Header Art Anita Tirone