Applied Geography formerly Rural Training Center, Thailand

2010 Jan 19 RTC-TH Programs: W.O.R.M.S.

Jan 19, 2010

W.O.R.M.S. (Working On Restoring and Making Soil) integrates basic low tech/no tech soil testing methods and strategies to managing the productivity of soil. Soil is a very precious resource for small family farms. S.O.S. focuses on soil erosion and strategies to limit its negative impacts. S.O.W. includes soil moisture retention as a water conservancy method.

In nature, soil making begins with heat and moisture breaking down solid rocks into smaller and smaller pieces. Soil is not ?“dirt?”; soil supports life. Soil is a mixture of mostly broken down (weathered or decomposed) rocks (about 50% of the bulk of a soil sample) and nearly equal parts of air and water (about 48%) and the remainder (~2% or less) made up of decomposed organic materials (humus). In a soil making recipie, the humus might be the ?“pinch?” of seasoning that makes all the difference.

Nature can take from one year or more to make ~24-25 mm of soil a year. It depends on the climate and the rocks on your farm. The worldwide average would be about 12-13 mm per year. For a farm, soil is like money. If the soil stays on the farm, that?’s like having money in the bank. Nature can remove soil from the farm (erosion). And nature can also put soil on a farm (deposition).

Soil studies begin with the most obvious soil characteristic: color. Color is a subjective characteristic. There are many methods used, but a simple low cost/low tech approach is to make a local comparative sample set. In this approach, soils are grouped as being light, medium or dark. Soil samples from your farm are glued to white cards. When compared/contrasted side by side, they are arrayed ranging from light to medium to dark.

Soil color can be a general indicator of soil quality, but it can also be misleading. For example, generally a darker soil might mean it has a high organic composition. But recent burning or oil contamination can also make a soil appear dark. To get more information, other less subjective

The particle size is measured as soil texture. The particle size is important for a number of reasons. Smaller particles, in a given quantity of rock, will have more exposure surface area than a larger block of an equal quantity of rock. Larger particles cannot be packed as closely together as smaller particles. The spaces between the particles affects how easily air, water, and plant roots can move through the soil. Measurement of soil particles can be done by gravity using the sedimentation bottle method. This will take about 24-48 hours or longer. Hand sampling and testing methods are faster, but may not give as consistent results as the sedimentation bottle.

Soil particles can be clumped together and measured in terms of structural characteristics. Soil structure also affects the movement of air, water, and roots in soil. It also affects the ability of soils to be easily eroded or to resist erosion. Simple test equipment can be made from discarded plastic water bottles or using simple tools (e.g. tape measure, shovel, and plastic tarp). Soil crumb bottle tests, soil percolation tests, and relative compaction measurements give farmers low cost methods to monitor soil structure and changes in structure over time.

Soil chemistry is very complex. It is usually measured by special and expensive laboratory procedures. We do some simple tests. One requires buying some test paper to estimate the soil pH (a measure of the acidic levels in the soil). A very simple test is to dig several sample holes around the farm and count the number of earthworms present. [Note: The RTC-TH soil testing training tries to minimize the work by performing multiple tests when sampling. For example, when digging a hole for the earthworm census, tests can also be done for texture and structure.]

The first time soil testing is done on a farm, the ?“base line?” is established. This is the starting point for the recordkeeping. It is important to keep good records to detect changes in soil characteristics over time. Any soil tests after the base line will help to show any changes over time. This will help farmers to know if their soil is improving or deteriorating.

Restoring efforts apply to soils in reasonable condition (indicated especially by a moderate earthworm count). Mulching and composting are the primary activities. These methods add organic matter to the soil with the aim of increasing earthworm populations. Worm composting is especially useful. The worms speed up the breakdown of the compost materials. At the same time, worm eggs are in the compost being applied to the garden beds and fields.

It is difficult to imagine how a small rural family farm can be treated all at once using our methods. It will take time. So we advocate starting in garden beds near the home. This approach makes it easier for the young and the elderly to do the work. Also, the produce from the garden is easy to get and use in the home. Well-composted gardens can often produce 3-5 times the yield of traditional field planted crops. This helps get the family closer to a degree of food self-sufficiency. Also, a garden planted with a variety of typical food crops (e.g. Thai egg plant, chilis, cucumbers, pumpkin, tomatoes, cabbage, lettuce, cilantro, chives, onions, corn, guava, star fruit, jack fruit, mango, longan, wood apple, neem, an array of Thai herbs, etc.) is diverse. This biodiversity is a stark contrast to the mono-cultured cash crop on many farms.

Composting ?“in place?” is used in orchard situations. When orchards are pruned, we advocate the creation of many smaller cold compost piles in between the trees. Over time the leaves separate from the cut branches. The wood can then be easily separated for use as firewood or making biochar (a valuable soil amendment to boost soil moisture and nutrient retention). The smaller cold compost piles can be ?“seeded?” with earthworms. As time goes by, these smaller compost piles are ?“pre-distributed?” throughout the orchard. So the farmer does not have to lift and haul compost. And the earthworms also do their part to move the compost into the soil. The space between the trees in the orchard are also closer to the drip line of the tree (the outer circumference of the branches) which is also closer to the root system of the tree and the rainwater dripping off the leaves. So having compost added here has a better chance of helping to ?“feed?” the trees.

For poor soil or areas not previously planted soil making efforts range from no diging, single digging (~30 cm deep) to double digging (~60 cm deep). No digging consists of clearing the garden bed surface of all vegetation, and cold composting in place. Spread a layer of compost materials and manure on the surface. Add some compost from a worm compost pile or add earthworms. Cover the area with thick layer of mulch (15-20 cm). As time goes by, the worms work the compost into the soil and the mulch breaks down. Do all of this well in advance (3 months or more works for us on our farm) before you expect to plant.

Changes in landuse may call for restoring compacted soils from foot paths, farm roads, or parking areas to productive use. Cold composting or sheet composting of the affected areas is a good approache. We try to avoid plowing as it damages or destroys soil structure making soils more easy to erode.

Single digging requires some work. Dig the garden bed down to a depth of 30 cm. We suggest starting by putting down some compost fortified with worm eggs and some manure. When you dig, simply turn over the excavated soil in place. This takes the surface soil layer with the overlying compost / manure and turns in down into the soil. [Note: If you have a soil with a high clay content, do not dig when the soil is wet. Wait until it is dry to do any digging.]

Double digging is used for areas not previously planted or for soils needing improved structure. This method is labor intensive. Start by laying out a system of 3 adjacent garden beds to be worked sequentially over time. As you proceed, you will have 3 parallel trenches. The trenches are 30 cm wide. The digging will proceed in 2 layers (top 30 cm and bottom 30 cm) to a depth of 60 cm. Make the length suitable for your site and strength do to do the work. You need to organize the work so you keep the soil from each layer separate. Have finished compost ready in sufficient quantity for 2 layers (each ~15 cm) per trench.

?• Dig out the first trench to a depth of ~30 cm. Put the soil in a separate pile. Dig out the bottom layer of soil to a depth of 30 cm. Put it in a separate pile.
?• Dig out the second trench. Put the top layer of soil (~30 cm) into the first trench to be the ?“new?” bottom layer. Add a layer of compost (~15 cm) and thoroughly mix it into the ?“new?” bottom layer of the firsst trench. When done, lightly water it with a sprinkling can. Then dig out the bottom layer of soil (~30 cm) in the second trench and put it into the first trench. Add a layer of compost ~15 cm and mix it thoroughly into the ?“new?” top layer of the first trench.
?• Dig out the third trench. Put the top layer of soil (~30 cm) into the bottom of the second trench. Add a layer of compost (~15 cm) and thoroughly mix it into the ?“new?” bottom layer of the second trench. When done, lightly water it with a sprinkling can. Then dig out the bottom layer of soil (~30 cm) in the third trench and put it into the second trench. Add a layer of compost ~15 cm and mix it thoroughly into the ?“new?” top layer of the second trench.
?• Put the soil from the top of the first trench into the bottom of the third trench. Add a layer of ~15 cm of compost and thoroughly mix it into the ?“new?” bottom layer of the third trench. When done, lightly water it with a sprinkling can. Then add the bottom layer of soil from the first trench to the top of the third. Add a layer of compost ~15 cm and mix it thoroughly into the ?“new?” top layer of the third trench.

In following years, maintenance of these beds should require composting the top layers. Subsequent soil testing gives you information to compare/contrast with the baseline soil data. Changes can reveal improvements or changes that require additional enhancement may be needed.

Regular crop rotation is a good practice to help maintain soil health. This also helps to avoid and reduce the potential for soil conditions making plants susceptible to various crop diseases. Biodiversity via intercropping and beneficial plantings of plants supporting pollinators and beneficial insects is also encouraged (more about this topic is covered in the BUGS?—Biodiversity Ultimately Gives Sustainability--- program).

[Note: This was a brief description of WORMS. For the lessons to be meaningful, they are all adapted to local site conditions prior to training. A typical scenario for off-farm training involves time to pre-view the area for the training (about ?½ to 1 day prior to the training). This lets us tailor the lessons to be as site specific as possible. Relevance is critical to making the lessons useful. Thus, there isn?’t a ?“standard?” lesson booklet as such. Included with the training is the ?“teach back?” model. This encourages the participants to share the knowledge with others, just as we are freely sharing our knowledge with them. Payment for the training consists of covering our costs to get to and from the training site, and room/board for the duration of the training. Although we are not a formal / legal non-profit organization, we conduct ourselves in that manner. We are not doing this to make a profit. This is primarily a ?“give back to the community?” activity.