Dryland techniques and mulches Hillside techniques Intercropping Sustainable systems: resources and training opportunities Poem by Larry Fisher. Dryland techniques and mulches See the Water Resources chapter for an introduction to farming in semi-arid regions. This is a traditional practice of digging a 20x20 cm hole 10 cm deep during the dry season and filling it with mulch such as crop residue or manures. This leads to increased termite activity [note termite tunnels] which, in turn, increases the rate of water infiltration when the rains come [see dotted areas on the diagram]. Soils here are infertile and if farmers have manure at all they just broadcast it on top of their fields. Much of this is baked, blown and washed away.
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Dryland techniques and mulches Hillside techniques Intercropping Sustainable systems: resources and training opportunities Poem by Larry Fisher. Dryland techniques and mulches See the Water Resources chapter for an introduction to farming in semi-arid regions. This is a traditional practice of digging a 20x20 cm hole 10 cm deep during the dry season and filling it with mulch such as crop residue or manures.
This leads to increased termite activity [note termite tunnels] which, in turn, increases the rate of water infiltration when the rains come [see dotted areas on the diagram]. Soils here are infertile and if farmers have manure at all they just broadcast it on top of their fields. Much of this is baked, blown and washed away. If the manure and organic matter are placed in a zai hole, losses are minimized and nutrients are concentrated where the plant can use them. Crop plants have a competitive advantage over weeds that are not in the zai hole.
The technique was originally used for hard pan soils which are uncultivatable using traditional farming methods. We convinced one farmer to try zais on a small plot of barren land.
He did and harvested kgs of corn and 15 kgs of sorghum. The next year farmers in 20 villages dug over 50, zai holes! We urged farmers to also try zai holes in their sandy soils.
The results were so convincing that many are now digging holes on their own initiative. Farmers in 87 villages dug almost two million zai holes for their millet. There have been more failures than successes because of the harsh climate and poor soils. Even in good years we have never had such a high success rate using other planting practices. I believe these trees will be very important in semi-arid to arid subsistence agriculture in the future.
Last year farmers here planted over 4, trees with a view to food production. They did this with no promise of food or money payments from us. The following is a summary taken from an article sent to ECHO. The zai or planting pockets are generally cm across and cm deep, spaced 80 cm or so apart.
They are often dug on land so badly degraded that water cannot infiltrate, so the holes collect and concentrate runoff. Organic matter added in the hole provides nutrients for the plants and stimulates termite activity, which can improve the hole. Tree seeds have also been successfully established in zai holes. A major advantage of these planting pockets is their ability to efficiently harvest rainfall and reduce runoff, thus improving overall soil moisture and fertility.
Farmers in Burkina Faso also spread straw on their fields to achieve the same benefits. Note that different species of termites behave differently, so a technique you read about in EDN may not work where you live. Victor Sanders showed me termite nests high up in trees in Haiti. He tried painting the trunk with neem leaf tea, which was reported to stop termite damage in Mali.
It had no effect in keeping this kind of termite from nesting in the tree. The zai hole technology described above is used where the "composting" species of termites is present, able to convert and enrich organic matter into good soil for the seedlings. However, the water harvesting and other benefits of this idea could be helpful even where there are no such termites. When I visited Jamaica, I learned that farmers in south St. Elizabeth Parish were growing a good crop of scallions.
What was unique is that they relied on rainfall in an area that is normally too dry for intensive vegetable production without irrigation. In fact, they were growing tomatoes, cucumbers, carrots, green beans etc. Working with the Jamaica Agricultural Foundation and the University of Florida, Mac and Pat Davis set out to study this indigenous system of growing vegetables in a guinea grass mulch. The following is based on their two-part study of scallion production.
Rainfall averages cm 50 inches annually during two brief periods in the spring and fall. In addition warm temperatures and high winds combine to rapidly dry the soil after the rains. Farmers have found that mulching with guinea grass Panicum maximum not only conserves moisture, but offers other benefits as well. In the study, all critical steps i. Replicated plots were all treated identically weeded, mulched with a layer of guinea grass and planted except that after planting the mulch cover was removed from half the plots.
Undisturbed fallow plots were left adjacent to each replication for comparison purposes. Plots mulched with Guinea grass were found to have significantly lower soil temperatures than the unmulched plots. Guinea grass mulch also greatly reduced the amount of weeds weed counts being up to five times as great in the unmulched plots.
Plots were harvested five times. Total yields, marketable yields, and mean bulb diameters were all greater in the mulched plots than the unmulched. According to Mac, the mulch system is used by all the farmers in the area and no vegetable production is attempted without it.
In addition to providing mulch for the principle crops, the grass is also an important part of the crop rotation, serving as a cover crop and sometimes as food for animals. While most farmers keep part of their land in grass and part in vegetable production, farmers with very small farms purchase the grass needed for mulch while those with larger farms grow extra for sale.
The second study focused more on soils, which in the area are well-structured, red or brown bauxitic loams with high aluminum content and near neutral pH.
In addition to the benefits mentioned above, this study showed a strong correlation between mulching practices and extractable soil phosphorus. This finely tuned system appears to be well adapted to growing scallions and other vegetables in that climate. The Davises believe that similar grass-mulch systems could be adapted to other dry areas. Guinea grass seems to be a particularly good mulch because it easily reseeds itself, produces a lot of biomass, dries down quickly and decomposes slowly.
While preparing mulch requires extra labor, less time is spent in weeding, watering etc. Might such a system allow farmers in other dry areas to intensively produce certain vegetables where they may not otherwise be grown?
The author believes so. Such a system would not only increase the farmers' profit potential over traditional crops in a region, but also provide a means for improving the nutritional status of a community.
Mac suggests "the best approach would be to begin on a small scale with subsistence garden plots until farmers become familiar with the technique and some marketing infrastructure can be developed. Gene Purvis, now working in Costa Rica, says that he used a grass mulch system in Panama. Normally his garden took daily watering. He reduced the time of each watering AND reduced the frequency to two times a week by running poly pipe with small holes drilled in it under a cover of chopped paragua grass.
He said that any tough, slow decomposing grass, when cut dry, would work well. Rice hulls worked well. Chopping the grass had several advantages. Martin Gingerich in Haiti learned about a traditional system using Guinea grass in Haiti. This is in an area near La Valee Jacmel at about meters and 2, mm 80 inches of rainfall. He wrote, "Just like the example from Jamaica, the system is used by all farmers in the area and no planting is attempted without it.
We couldn't find anyone who remembers when people started using the system. It is older than those using it today. There are plots that have only Guinea grass, often owned by larger landholders. Once a year the grass is harvested.
A farmer wanting to plant a grain crop in the coming months will purchase and harvest a plot of Guinea grass, which he spreads over the entire field that he intends to plant. These are not large fields. The next step is to tie an animal in the plot to eat and trample the grass. They use horses, burros, mules, cattle and goats. Pigs are tied near the house and their refuse is carried to the field.
After the farmer removes the animal from the field he lets it set weeks. He then deeply tills the field with a pickaxe, incorporating some of the Guinea grass and leaving some on the surface. Planting is soon after tillage. Black plastic mulches reduce weeds, conserve soil moisture, and warm the soil in cold climates. Colored mulches provide these benefits while also reflecting light up to the plants, giving yield benefits such as larger fruit or earlier maturity.
Michael Kasperbauer, who studies plant response to the light spectrum. He explained that not all shades of color have the same effect on yields.
The key factors are the amount of reflected far-red and the ratio of far-red to red light, which can only be measured with a spectroradiometer.
A high FR:R ratio of the reflected light stimulates above-ground growth, so many fruit crops respond favorably on certain red mulches. Cotton plants produce more bolls with longer fibers. Pigments which reflect a low FR:R ratio, in contrast, stimulate root growth.
Some colors such as yellow attract insects, and growers can use this factor in pest management. In one trial, cucumber beetles infested yellow-mulched rows first; it may be possible to attract pests to one area of a field for spot treatment. Colored mulches tend to cost more than black plastic, and manufacturers have yet to standardize the color intensity in the mulches for best production.
This idea may be worth some experimentation in your fields. Research in this area began by painting black plastic with different colors. Let us know your results. I MLP first read of this method of gardening in Organic Gardening where it was referred to as permanent mulch gardening. My reaction was that there must be something wrong with anything so easy or everyone would be using it.
Amaranth to Zai Holes: Ideas for Growing Food Under Difficult Conditions
I made a special trip to Haiti about a year ago to meet Victor Wynne and to see his interesting small farm in the mountains. After walking through eroded hillsides and unimpressive "fields," we suddenly came to a beautiful productive area that seemed like the Garden of Eden by contrast. Victor has experimented with better methods of terracing for some time, combining his training as an engineer and his love of plants. He has at least three distinct systems. He has written a description of one to share with our network, which follows. Protective measures to conserve soil must come first.
Amaranth to Zai Holes, Ideas for Growing Food under Difficult Conditions
This is a book of practical ideas. It is written for people who help those who live and make their living under difficult conditions in the tropics and subtropics. What should a development worker do to assist a community? There are no simple answers, but there are many possibilities--plants, techniques, and technologies--which hold potential.