To begin this method it is necessary to construct deep beds of organic matter which will provide support and fertility for the crops. Any leafy plant can be used as long as it is not one known to suppress the growth of other plants. Grasses work best, but large leafed plants can be used as long as the leaves are chopped up so as not to mat up in the beds.
The soil does not have to be tilled before the bed is constructed. However, if possible, a shallow tilling of the soil is helpful in getting roots established in the first year. The bed can, in fact, be built right on top of growing sod with good results.
Each bed should be about one meter wide and about half as tall. The length is not important. However, breaks every so often do allow easy access to the other side. The beds need to be kept moist during the growing season, especcialy until the first years crop has a chance to put plenty of roots down into the soil. In following years this will not be as critical because the bed will have decomposed to an extent that it will act like a sponge.
Potatoes are a good choice for the first years crop. But, cassava or another tuberous crop would work also. Begin by making a bed of half the final thickness and place two rows of small, whole seed potatoes on top of this. Each row should be positioned about a third of the way in from the edge and should extend the full length of the bed. Cut seed potatoes will work, but, not as well.as whole pieces that are a little larger than a chicken egg. If cut potatoes are used make sure that each piece contains some of the tiny sprouts and let the cut heal for a few days before planting. Keeping the beds moist until the plants flower will insure a good crop. At flowering, the water should be reduced to only enough to keep the soil from drying out.
Potatoes can be harvested at any time by pulling part of the bed aside to expose the tubers which will mostly form above the ground inside the bed. After harvesting some tubers, the organic matter needs to be pushed back into place. In good years it is a good idea to do some early harvesting of the largest tubers to prevent potatoes from getting too large and developing hollow centers. Once the tops die back, all the tubers should be harvested by pulling the plant to one side and picking all remaining tubers. The vines should be left on the bed to decompose.
The potatoes should be left in a shollow layer to dry in a well ventillated location which is protected from sun and rain. They can then be stored in mesh bags or in airy cribs made of sticks. They should not be washed until used or they will rot. The one dissadvantage to this system is that the potatoe skins retain a musty taste if not peeled and Peeling reduces the nutrient content. I have never tried boiling them to see if it would eliminate the problem.
The beds should be pulled back together into a low mound.
Sweet potatoes or yams can be grown in the second year, especially in the tropics where heat and humidity speed up decomposition of the beds. But, in cooler areas the third year is the best time to plant sweet potatoes, yams or cassava with squash, gourds or cucumbers grown in the second year. Sweet potato slips should be placed in cups of soil made of folded leaves until a root ball is formed. The bed should be formed into a low mound with holes every 3'(1M). Expose the root ball and place the plant into the hole with the roots in contact with the ground. 3-4"(8-10cm) of stem should stick out from the top. Pull the bed in around the stems and keep the beds well watered. Lift the stems often to prevent them from taking root.Delay the harvest as long as possible as the roots put on most of their growth late in the season. The roots may extend into the soil and may require some digging. Leave them in a warm shaded spot for two weeks and then store wrapped in paper or dried leaves in a cool location. Rake the beds back into a mound and leave the vines on top to decompose.
In the third year squash, melons, cucumbers, pumpkins or gourds can be grown by making craters in the beds every 3'(1M) and planting into the soil. Thin them to 1-2 plants per hole and keep them trained onto the top of the bed. When the top of the bed is covered by vines you can prune any branches that grow out into the path. Harvest winter squash and pumpkins when the fruits look ripe and the rind is hard. Be sure to leave a portion of stem attached or it will rot. Store them in a cool airy place with the fruits not touching each other. Harvest gourds after they are hard and as dry as possible. Let them completely dry before using them.