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Contour line
INTRODUCTION
A central element of soil conservation on sloping land is thecorrect establishment of contour lines. If contour lines are incorrectly established, then they can actually increase the risk of erosion. Therefore, it is very important that farmers understand the concept of contour lines and are initially assisted to correctly establish these.
PRINCIPLE
Contour lines are lines that nun across a (hill) slope such that the line stays at the same height and does not run uphill or downhill. Contour lines are used in the establishment of hedgerows, pasture strips, canals, etc.
DISTANCE APART
Generally, contour lines are established so that the vertical distance between the lines does not vary. For erosion control, the rule of thumb is: vertical fall between contour lines is about 1 meter on steep slopes (above 15 percent), reducing to 0.75 meter on greater slopes (below 15 percent).
The horizontal distance between two
contour lines will vary as the steepness of the slope changes.
The steeper
As contour lines travel across a hillside, they will be close together on the steeper parts of the hill and further apart on the gentle parts of the slope.
Contour lines
HOW TO ESTABLISH CONTOUR LINES
1. Use an A-frame, O-ring or water level to determine the contour lines. (See pages 37-38).
2. Start in the middle of the slope, work down to the bottom of the area, then work upwards to the top. By starting in the middle, you minimize cumulative errors. Some people prefer to start work in the steep section, some at the top.
3. Make sure that the base of the instrument stands as a representative site (not in a hole or on a hill).
4. Ignore small disruptions to the general slope.
5. Place stakes at least every 3-6 meters along the contour line or closer if desired (every first pivot of the A-frame). Make sure that stakes are driven well into the ground. Place the stakes closely (3 meters) if the ground cover is tall or dense and/or if the slope is steep with rapid changes.
6. The vertical spacing (1 meter) between contour lines can be measured by sighting over a "T-stick" of appropriate height (1 meter) back to the previous contour line (working downhill: or from the previous contour line uphill (working uphill).
Working downhill
Working uphill
INSTRUMENTS
1. A-frame (See Making an A-frame on pages 1001 03.)
with carpenter's level
with string plumb bob
2. O-ring
To make:
· Fill one-meter length of clear plastic tube (15 mm diameter) half full with colored water using the extracts from achuete or duhat.· Form the tube into a circle by bending it into a circle and inserting one end into the other end. Heat or hot water may be used to soften the outer end to make it easier to insert the other end into it.
· Attach the ring to the top of a stick. String, tape or nails can be used to attach the ring to the stick. The stick should be about as tall as the person using it. The level of the water in the Oring will then be at eyeheight.
· Make another stick (staff) the height of the water level in the tube. A small bar painted a bright color for visibility can be attached to the top of the stick.
To Use:
One person holds the stick with the ring while another holds the stick with the bright-colored bar. The person with the ring directs the person with the bar who stands 36 meters away to move up or down the hill, using the water levels in the ring and the top of the bar as guides. The site is correctly located when the water in the ring is level with the top of the bar. A stake is placed at the foot of the stick with the bright-colored bar.
O-ring
3. Water Level
To make:
· Purchase eight meters of dear plastic tube (510 mm diameter).· Attach the ends to two sticks of equal height (two meters) with a mark at the eye-level leaving about 50 cm. of tube above the eye level mark.
· Fill the tube with colored water to the level of the top of the two eye-level marks. Then, seal the ends of the tube.
To Use:
· One person holds one stick, another person takes the other stick out along the contour and locates the site where the water level is steady at the eye-level marks. A stake is driven at this spot.· The two people then move so that the first person walks to the site of the second and the second moves to a new site along the contour.
Water level
Helpful hints:
1. Study the land first and visualize where the contour lines will run.
Same level
This may be done best by having one person direct another person in walking to the other side of the area to be contoured such that he/she stays at the same height as the first person.
People
Also try to visualize what the area will look like when terraced -- particularly the height and width of the terraces. This can be assisted by using a "T-stick" and string.
Using a “T-stick”
2. Always look behind at the line of stakes and assess whether you are running level.
3. Get a feel for the main direction of the slope. The contour line will run perpendicular to this direction.
4. Establish your contour lines at a time when labor requirement for other farm operations is low.
However, do not leave the stakes for a long time before cultivating or sowing because the stakes may be displaced by livestock or children.
5. Land that has been cleared but not cultivated best to work on. If the land has been cultivated, the site for placing the staff or leg of the A- frame should be roughly levelled with the foot.
6. Cultivation of the whole area creates problems in establishing seeds or seedlings because heavy rain will wash away seeds and seedlings.
7. Encourage neighboring farmers to work together to plan the contouring and layout of hillsides. In this way, contour lines can be connected and drainage systems protected.
8. If stakes are close together when plowing or seeding, do not follow the exact contour line from peg to peg (Doing so will create a zigzag line), but look ahead and smooth out the line by taking a line of "best fit" between the stakes.
Smooth out the zig-zag
line
Land lines
SALT-1 is a one-hectare model of agroforestry technology with agricultural and forestry crops at a percentage of 75:25. Based on the experience of the Mindanao Baptist Rural Life Center (MBRLC) in Bansalan, Davao del Sur, this technology decreases erosion by 50 percent, as compared to the traditional upland farming system. In addition, it increases com yield by about five times and income by six times.
This information material will guide you on how to establish SALT-1.
SALT is a simple, applicable, low-cost and timely method of farming the uplands. This technology was developed for farmers with few tools, small capital and little knowledge in agriculture. A farmer can continue his traditional farming practices in the SALT system.
If farmers leave the SALT farm, like some tribals in Mindanao do, the nitrogen-fixing trees and shrubs (NFT/S) will continue to grow and overshadow the crop area. By the time the land is again cultivated, the soil has already been enriched by the large amount of leaves from the NFT/S, which also prevents erosion. In addition, the NFT/S, particularly the woody species, may be harvested for firewood or charcoal as additional source of income. Findings of MBRLC show that a hectare of SALT farm can provide an income of P1,3001ha/mo as against the P200/ha/mo in upland farms of corn cultivated the traditional way. Another benefit of SALT-1 is that it is less laborious than the traditional method of upland farming.
Here's how to put SALT-1 in your hillyland:
Step 1: Make an A-Frame. The A-frame is a simple device for laying out contour lines across the slope. It is made of a carpenter's level and three wooden poles nailed together in the shape of a capital letter A with a base of about 90 cm. The carpenter's level is mounted on the crossbar. (Other methods of making an A-frame are discussed in Making an Aframe, pages 100-103.)
A-stick
Step 2: Locate the contour lines using the A-Frame. One leg of the A-frame is planted on the ground; then, the other leg is swung until the carpenter's level shows that both legs are touching the ground on the same level. A helper drives a stake beside the A-frame's rear (first) leg. The same level-finding process is repeated with stakes every five-meter distance until one complete line is laid out. The distance of contour lines is three to five meters apart.
Locating
Step 3: Prepare the contour lines. After finding and marking the contour lines, prepare them until ready for planting. The width of each area to be prepared should be one meter. The stakes will serve as guide during plowing
Preparing
Step 4: Plant seeds of nitrogen-fixing trees and shrubs (NFTS/S). On each prepared contour line, two furrows are laid out. Plant two to three seeds per hill at a distance of one-fourth inch between hills. Cover the seeds firmly with soil. When fully grown the hedgerows bank the soil and serve as source of fertilizer. Examples of hedgerow species are Flemingia macrophylla (syn. congests), Desmodium renzonli, Calliandra calothyrsus, Gliricidia septum, Leucaena diversifolia and L. Ieucocephala.
Planting seeds
Step 5: Cultivate alternate strips. The space of land between the thick rows of nitrogen-fixing trees and shrubs where the crops are to be planted is called a strip or alley. Cultivation is best done on alternate strips. Altemate cultivation will prevent erosion because the unplowed strips will hold the soil in place.
Strips
Step 6: Plant crops. The permanent crops like coffee, cacao, banana, citrus and others of the same height may be planted at the same time the nitrogenfixing species are sown., In areas which are not cultivated, only the spots for planting are cleared and dug and, later, only ring weeding is employed until the hedgerows are large enough to hold the soil in place. Plant permanent crops in every third strip. Tall crops should be planted at the bottom of the farm to avoid shading.
Citrus + Banana
Step 7: Plant short-term crops. Plant short and mediumterm income-producing crops (pineapple, ginger, taro, potato, peanut, mung bean, melon, sorghum, corn upland rice, etc.) between the strips of permanent crops as a source of food and regular income while waiting for the permanent crops to bear fruits. To avoid shading short plants are planted swan from tall ones
Short term planting
Step 8: Trim the contour hedgerows regularly. One year after planting the hedgerows, cut the hedgerows at a height of 40 centimeters from the ground every 30 to 45 days. Always pile the cut leaves and twigs at the base of the crops. These cuttings serve as an excellent organic fertilizer for the crops.
Trim the contour
Step 9: Rotate your food and cash crops. A good way of rotating is to plant cereals corn, upland rice, sorghum, etc.), tubers (sweet potato, cassava, gabi, etc.) and other crops (pineapple, castor bean, etc.) on strips where legumes (mung bean, bush sitao, peanut, etc.) were planted previously and vice versa. This practice will help maintain the fertility and good condition of the soil. Other management practices in crop growing like weeding and pest management should be done regularly.
Rotating
Step 10: Maintain your SALT-1 farm. Apart from providing you with adequate food and sufficient income, an even more important benefit of using SALT-1 is the control of soil erosion. This is done by the double thick rows of NFT/S and the natural terraces being formed along the contour lines of the hill. To enrich the soil and effectively control erosion, always pile straws, stalks, twigs, branches, leaves, rocks and stones at the base of the thick rows of nitrogen-fixing species. As the years go by, strong, permanent and naturally green terraces will be formed which reliably anchor the precious soil.
Maintaining
SALT-1 can be adapted throughout the country, particularly in the uplands. SALT-1 is now being adopted in several Asian countries, among them Indonesia, India, Thailand, Sri Lanka, Nepal, Cambodia, Vietnam, Nigeria and Congo. But even then, MBRLC believes SALT-1 is not a perfect farming system despite its popularity. No system can bring depleted, eroded soil back into production in a short span of time. But land can be restored, upgraded and sustained to a reasonable level of productivity by using SAL Tel.
Table 1. ADVANTAGES OF SALT-1 OVER THE TRADITIONAL UPLAND FARMING SYSTEM.
| |
TRADITIONAL FARMING |
SALT-1 |
|
Soil erosion |
194.3 m.tJyr |
3 4. m.t./yr |
|
Crop productivity |
less productive |
more productive |
|
Net income |
P300.00 |
P1,300.00 |
|
Labor |
High Labor |
Low labor |
|
Hedgerows |
None |
Two strips |
|
Organic fertilization |
None |
Free 3,000 kls. biomass/ha/yr |
During its establishment, SALT-1 is more laborious (planing of hedgerows and permanent crops) than the traditional farming In the subsequent years, SALT-1 decreases its labor requirements (cultivation and weeding is lessened; only pruning is practiced); whereas, in traditional farming, constant cultivation, regular planing of crops and regular weeding are still required.
Source: MBRLC Editorial Staff (1990). How to Farm your Hilly Land Without Losing Your Soil. MBRLC, Kinuskusan, Bansalan Davao del Sur. 24 pp. How to Serbs No.1
Nob: The crops mentioned earlier are just suggestions. Farmers can use other crops suitable to their areas.
Contour rock walls are soil conservation structures which are generally constructed where there is an abundance of rocks. The technology is very labor intensive and is generally accomplished through labor exchange groups (i.e., bayanihan, alayon) rather than individually. The structure is more permanent than other soil erosion barriers. Several steps are involved in rockwall construction.
Steps
1. Starting from the upper side of the farm lot, excavate a drainage canal which gently slopes (1121%) towards a nearby gully. The canal will prevent water from flowing onto the farm from the land above.
2. Use an A-frame to mark a contour line on the hillside and below the drainage canal. Smooth the curve of the contour line.
Excavate
3. Excavate a base for the rockwall between 50-100 cm wide, 10-25 cm deep, and with a reverse slope to the base (i.e., slopes downward from the edge of the slope onto the hill.)
4. Begin construction by using large rocks for the base. The flatter, heavier sides should be placed outward. Smaller stones are used to fill in spaces between larger stones. Do not use small rocks for the base and place large rocks on top. This is unstable. Build one layer at a time. Tamp the stones to make the layer firm before starting another layer.
Constructing
5. The height of the rockwall will vary but, if possible, should reach the vertical height of the mid-line between the contour lines. If a shorter wall is initially constructed, it should be raised if the soil caught behind it reaches the top.
6. The sides of the rockwall should be gently angled for stability. The top should have a smaller width than the bottom. Generally, the top width of 50-70 cm is used for a onemeter-wide base. Walls shorter than one meter have narrower tops.
7. Rock walls should be constructed 3-5 meters apart for steep slopes, 5-10 meters apart for medium slopes and up to 20 meters apart for very gentle slopes.
8. During heavy rains, soil will erode from the base of the downhill side. The depression created will eventually enlarge, creating an unstable situation. The wall may eventually fall. Regular maintenance and suggestions listed below will help solve this problem.
Scouring
9. To further stabilize the rock wall and reduce the chance of a washout, Glincidia or other fast-growing legume trees can be planted 10 cm from the wall and 15 to 30 cm apart within the row on the downhill side. The legume trees below the wall will help hold it in place. It can provide firewood, forage fertilizer and windbreakers.
Wall
10. Napier or other forage grasses can be planted on the upper side of the wall. Newly eroded soil will wash down the hill and be caught behind the wall. This will help fertilize the grasses. The grasses can, be used as forage or fertilizer (i.e., green manure, mulch).
Wall
CONSIDERATIONS
1. In many places, rockwall construction is a continuous process. Because of the labor input, only a portion of the wall may be constructed at any one time. The wall gradually increases in height as rocks are cleared from the field and as more time is devoted to the activity.
2. There are examples of rockwalls combined with other soil conservation technologies. One example is the combination of a canal, hedgerow and rockwall. The hedgerow is planted directly above the canal while the rockwall is built along the upperside of the hedgerow. Bench terraces are often combined with rockwalls. In this case, the rockwall stabilizes the terrace riser. (See Terraced Agricultural Land Technology, page 81.)
3. Sometimes, grasses are placed below the wall. If this is done, Vetiver grass (Vebvera zizanioides) is recommended. The planting distance is 10-15 cm from the wall and 30 cm between clumps.
4. If napier grass is planted on the upper side of the wall, care must be taken to manage the grass. Napier tends to spread out and will invade the cropping area if not regularly cut. This is not so much a problem if a clump grass, such as Guinea grass, is used. Napier or other grasses can serve as homes to rats and other pests if not regularly inspected and harvested.
5. Rockwall systems should be tied up to the overall soil conservation system in the farm. This is critical if there is excess water accumulating behind the rockwall and must be safely removed from the area.
6. Rockwalls have many empty spaces in between rocks which can become the home of agricultural pests such as rats and snails. Successful local methods to solve these pest problems are: (a) regular inspection while using a dog to locate and chase the rats and (b) regular hand-picking of larger snails while employing one or more ducks to eat the baby snails.
7. Farmers have used legume trees planted below the rockwalls in different ways. Among these are: (a) allowing one tree to grow taller at 5 m spacing and cutting it as firewood when thick enough; (b) cutting the hedgerow at 1 meter height for forage and/or green manure fertilizer; and, (c) allowing the tree to grow two meters and keeping it pruned at that height so it acts as a windbreak for the area behind the rockwall.
Legumes trees as windbreakers
One practice made by IIRR to prevent leguminous trees (i.e., ipil-ipil) from jumping lice (psyllid) attack is to pollard them higher than normal (above 2 meters). In this manner, the birds could easily pick on the psyllids, thus, putting them under control and lessening the threat of damage or of drying up during drought periods.
Vetiveria zizanioides L. Nash, also known as Vetiver grass, Khus, Moras or Mura is densely tufted, perennial clump grass, with stiff leaf blades. The foliage is mostly basal with the leaf sheaths closely overlapping, strongly compressed and keeled which creates a physical barrier of great density at the ground surface.
Vetiver grass
VETIVER GRASS:
THE RECOMMENDED PLANT
Vetiver grass has the following characteristics that make it ideal for permanent, effective and simple to establish and maintain soil and water conservation measures:
1. It is easy to propagate and establish as a hedge.2. It is adapted to a wide range of soil and climatic condition.
3. When planted correctly, vetiver grass will form a dense permanent hedge in less than one year.
4. It has a strong root system that penetrates and binds the soil.
5. It is perennial and requires minimal maintenance.
6. It will not spread to the alleys since it does not spread by rhizomes nor from seeds.
7. Its crown is below the ground surface which helps protect the plant againts fire and overgrazing.
8. Its sharp leaves and aromatic roots are reported to repel rats, snakes and other pests. However, if leaves are not pruned, maya birds (Lonchura ma/acca) have been found to build nest among its dense leaves attracting snakes and rats.
9. Its leaves and roots have demonstrated a resistance to most insects and diseases.
10. It is generally unpalatable to livestock. The young leaves, however, can be used as fodder, especially during drought.
11. It can withstand drought, flood and long periods of waterlogging.
12. Vetiver hedgerows have minimal space requirements.
13. It does not compete as much with the crop plants it is protecting compared with other grasses.
14. It is compatible with any crop (e.g.' com, sweet potato, vegetables) or other hedgerow grass and legume species (e.g., rapier, ipil-ipil, madre do cacao, etc.).
15. It is abundant in many places in the country.
STEPS IN ESTABLISHING VETIVER HEDGES
1. Locate the contour lines using an A-frame and make the furrows.
2. Prepare the planting materials:
· Dig the vetiver clumps with a digging flat bar.
· Tear a handful of the vetiver grass from the clump and further sever the root divisions or slips.
· Cut the leaves 15-20 cm from the base.
· Trim the roots 8-10 cm below the base.
Trim the roots
3. Just like planting rice seedlings, plant one or more slips in single rows along the contour furrows 10-15 cm apart at the start of the the rainy season
Planting the roots
4. Replant dead vetiver slips for gap filling.
5. Trim the vetiver hedges 40-50 cm from the ground after they have properly established to encourage tillerino and avoid shading of adjacent cross.
Trim the vetiver
6. Plant fast-growing leguminous trees/shrubs every 2 m just above the vetiver furrow lines and prune no less then 1.5 m 1 m high
Pruning
7. Vetiver can be planted below contour bunds It can also be paired with leguminous tree and shrub species planted on the upper side of the bund.
Vetiver grass is used extensively in India for control of sheet erosion on vertical soils or flat lands. It also serves the purpose of a fire break.
Figure
The leaves are sometimes used for mulching and rooking.
References:
Vetiver Grass (Vetiveria zizanioldes): A Method of Vegetative Soil and Moisture Conservation. 2nd Edition. J.C. Greenfield, Works Bank. New Delhi. April 1 988.
MURA Ang Tanom nga Mopugong sa Pagkeanas sa Yuta. Basahon I, FARMI, ViSCA, Baybay, Leyte. 1991. OnFamn Research Notes. Issue No. 5, FARMI, VISCA, Baybay, Leyte, Febnuary 1991.
Grasses play an important role in stabilizing sloping areas. Species like rapier/elephant grass (Pennisetum pupereum), Guinea grass (Panicum maximum) and NB21 (rapier crossed with pear' millet) grow vigorously and are ideal for their soil-binding properties. They are also good sources of fodder for livestock. However, if the farmer is more interested in essential oils rather than livestock, he can plant citronella (Cymbopogon nardus Jowitt) and lemon grass (Cymbopogon citratus Stapt). Grasses have the advantage of establishing easily although they could compete for moisture in waterlimited situations.
GRASSES AS SOIL BARRIERS
Plant the grasses along the contour lines to minimize surface runoff/erosion in cultivated sloping farms Soil will begin to collect behind the grass barrier even within the first year of establishment.
Soil barriers
Where feasible, contour earth bunds may be constructed and then planted with grass to stabilize the structure against breakages or breaches. Grasses must be regularly trimmed and used as feed for livestock or as mulch for the crops. Trimming of stems and clumps reduces shading and controls growth. Otherwise, the untrimmed grass may become a problem (i.e., it may later be considered a weed).
Soil barriers
GRASSES AS SOIL BINDERS
Stabilizing grass species have also been proven effective in firming up the riser of terrace structures. They prevent soil erosion and the collapse of the terraces.
The space between the drop structures, the bed and the sides of the waterways should be well-sodded with guinea grass to protect it from erosive water. In addition, rows of napier grass 40 cm apart can be planted along the lip/edge of the terrace. This will increase the protection of the risers, discourage farmers from cultivating the edge and provide an additional source of forage.
Note: The limitation of this grass-based technology is the lack of nitrogen-rich green leaf manure that fast-growing leguminous trees could provide.
Napier grass and guinea
grass
The adoption of alley cropping or contour farming using living hedgerow barriers continues to gain popularity with farmers in the Philippines. The initial success.with ipil-ipil (Leucaena leucocephala) was followed by a devastating infestation of the jumping plant lice (Heteropsylla cabana). This pest eliminated much of the ipil-ipil in the country and caused farmers, technicians and scientists to reconsider the use of a single species in alley cropping hedgerows. This experience has stimulated trials with a wide range of plant species and had reinforced the need for diversification in hedgerow planting.
It is important to select carefully the hedgerow species which are suitable to local conditions and the needs of individual farmers in discrete locations. The range of useful species offers many options for farmers; however, they must consider carefully the objectives and constraints they are working under. Selection of species for hedgerows should include the following consideration:
1. Main objectives
- erosion control
- legume or fixes nitrogen from the
air
- fuelwood
- green manure
- livestock fodder
- herbage
production
2. Rainfall
- amount and distribution (number of dry months)
- drought
tolerance
3. Type of soil
- textural characteristics
- depth
- pH; acidJalkaline -
fertility 4. Elevation 5. Others
- pruning tolerance
- deep-rooted or
tap-rooted propagation
- germination ability/livability of planting materials
nitrogen-protein content
- availability of planting materials/seeds -
origin
- pest resistance
The main hedgerow species are perennial members of the legume family. In addition, several types of grasses have been used. The list of the key plant species which are currently being utilized as hedgerow species in the Philippines, with information on their suitability under the various conditions described earlier is shown in Table 2.
Peasant
TABLE 2. HEDGEROW SPECIES
|
SCIENTIFIC NAME |
COMMON NAME |
USES' |
ELEVATION (meters) |
DROUGHT TOLERANCE |
pH TOLERANCE |
|
A. LEGUME SPECIES | |||||
|
Acacia confuse |
|
GM/FW | | | |
|
Acacia villosa |
Villosa |
GM/FW | | | |
|
Calliandra calothyrsus |
Red Calliandra |
EC/GM/FW/AF |
0-2000 |
Mode rate |
AcT |
|
Calliandra tetragona |
White Calliandra |
EC/GM/FW/AF |
0-2000 |
Moderate |
AcT |
|
Calliandra |
Fireball |
EC | | | |
|
haematocephala |
| | |
| |
|
Cassia siamea |
Thailand shower |
EC/GM/FW |
0-t500 |
Excellent |
WT |
|
Cassia spectabilis |
Antsoan dilao |
EC/GM/FW |
0-1500 |
Moderate |
AcT |
|
De/onix regia |
Fire tree |
EC/GM/FW |
0-2000 |
Very good | |
|
Desmodium rensonii |
Rensonii |
EC/GM/AF |
0-1000 |
Moderate | |
TABLE 2. HEDGEROW SPECIES
|
SCIENTIFIC NAME |
COMMON NAME |
USES' |
ELEVATION (meters) |
DROUGHT TOLERANCE |
pH TOLERANCE |
|
Erythrina posppioiana |
Dapdap |
EC/FW/GM |
0-1900 |
Good | |
|
Flemingia macrophylla |
Flemingia |
ECIGM/AF |
0-2000 |
Moderate |
WT |
|
Gliricidia sepium |
Kakawate |
EC/GM/FW/AF |
0-1500 |
Good |
WT |
|
Leucaena diversifolia |
Acid ipil-ipil |
EC/GM/FW |
0-2000 |
Moderate |
AcT |
|
Leucaena bucocephala |
Ipil-ipil |
EC/GM/FW/AF |
0-2000 |
Very good |
NAc |
|
Parkia noxburghn |
Kupang |
EC/FW |
0-2000 |
Good |
WT |
|
Piliosbqma ma/abancum |
Butterny |
EC/AF/FW/GM |
0-1500 |
Good |
WT |
B. GRASSES
|
Pannicum maximum |
Guinea grass |
EC/AF |
0-2000 |
Good |
WT |
|
Pennisetum purpureum |
L Napier grass |
EC/AF |
0-2000 |
Moderate |
WT |
|
P. purpureum (hybrid) |
NB-21 grass |
EC/AF |
0-2000 |
Moderate |
WT |
TABLE 2. HEDGEROW SPECIES
|
SCIENTIFIC NAME |
COMMON NAME |
USES |
ELEVATION (meters) |
DROUGHT TOLERANCE |
pH TOLERANCE |
| | | | |
2 |
3 |
|
Setaria so. |
Setaria |
EC/AF |
0-2000 |
Good |
WT |
|
Vetiveria zizanoides |
Vetiver grass |
EC |
0-2000 |
Excellent |
wT |
C. OTHER PLANTS
|
Ananas comosus Pineapple |
AcT |
EC/F |
0-1500 |
Moderate |
|
Hibiscus rosa-sinensis Gumamela |
EC/GM/AF |
0-1500 |
Moderate |
WT |
'Uses: Erosion control (EC), green manure (GM), fuelwood (FW), animal fodder (AF), source of food (F)
'Drought tolerance: Excellent (withstands long drought periods), moderate (moderately tolerant of extended dry periods, poor (requires high, evenly distributed rainfall
'Son conditions: AcT (tolerance to acidic conditions), WT (wide tolerance to soil conditions), NAc (not tolerant of acid soils)
Nob: A variety of additional plants is currently being tested for suitability as hedgerow species. These are not listed until they have been proven appropriate
Contour Canals
In sloping farmlands where soil is relatively deep, a system of canals and other physical structures built can effectively minimize soil erosion and conserve water. These structures are the drainage/diversion canal, contour canal, contour-drainagecanal, contour bund, check dam and soil trap
FUNCTION OF THE STRUCTURE AND ITS CONSTRUCTION
1. Drainage/Diversion Canal This is the first structure to be built on the farm. The purpose of a drainage or diversion canal is to catch the water coming from above the farm or from other canals and divert its flow towards a nearby gully, thus, preventing damage to the farm
· It is recommended to build the drainage/diversion canal first before the other structures.
· Start digging from the uppermost portion of the farm. The canal should be sloping gradually across the farm at about one percent drop towards a gully. Size of drainage canal depends upon volume of water and slope
1% drop
· Place the excavated soil on the lower portion of the canal to form a bund or mound.
· Tamp to make bund farm.
· Stabilize bund by planting grasses and leguminous hedgerow.
· Plant creeping grasses along the sides of the canal to help slow down water current and to prevent sides from scouring.
· It is suggested that farmers agree on a Common drainage outlet, if necessary.
Bund
2. Contour Canal. This canal is built on a contour to hold the water and allow it to seep into the ground, thus increasing soil moisture and replenishing the aquifer. This structure is suitable on porous soils.
Drainage canal
· Using an A-frame, determine a contour line 3m-5m below the drainage canal and at every 3m-5m interval down the slope until the whole canal system is finished. Smoothe curves of the contour line.
· Dig a canal at least 50cm wide × 30cm deep following the contour.
· Place the excavated soil from the canal on either side of the canal.
Figure
· Tamp the soil to make a firm mound.
· Plant grasses and leguminous spp. on the mound.
3. Contour-Drainage Canal. This is a contour canal built with a gradual slope towards a drainage canal. At the point where this canal is about to join the drainage canal, it is blocked by a mound of soil 112 the height of the canal. This will prevent water from flowing out. Only during excessive rain is the block removed to allow water to flow into the drainage canal. The contour-drainage canal serves two purposes: a) to hold water when rainfall is minimal and b) to remove excess water to prevent flooding and waterlogging. This structure is recommended in heavy soils.
· Contour-drainage canal is constructed similar to a contour canal except that it gradually slopes at one percent droo into the drainage canal.
· Place excavated soil on the lower side of the canal.
· Place a mound of soil at the lower end of the canal.
· Tamp the soil to make firm mound.
· Plant grasses and leguminous spp.
Contour drainage canal
Soil block
4. Contour bund is the firm mound of soil formed during the construction of the canals. During rain, water and the soil carried by it are initially collected at the depression at the. base of the mound and the strip. The excess water and the soil canted by it collect at the canal before the mound or bund, in case canal is below the bund or by the canal in case the bund is below the canal.
Before and after
5. Check Dams Moving water dislodges soil particles and carry these particles away, thus causing erosion. A check dam slows down water flow and allows heavier soil particles to settle down.
Check dams
· In a drainage system, drive
stakes into the ground, perpendicular to the water flow.
Gliricildia makes an
ideal "live" peg if it is available. The cuttings will grow and form a permanent
living barrier. Arrow root and vetiver grass planted across the canal will serve
as good check dam.
· Weave split bamboo strips between the pegs but not very closely. The aim is not to stop the water but to slow down its flow. Periodically clean the area above the dam.
· Begin constructing dams from the top portion of the drainage canal or gully. The steeper the slope, the closer together the dam should be.
6. Soil traps. The purpose of this structure is to catch soil carried by water in a drainage system and to slow water flow. It is placed about 1/2 m above a check dam.
Soil trap
· In a drainage system (drainage diversion canal, contour-drainage canal or gully), dig a pit at least 0.8 m. deep × 1.00 m long and 0.5 m wide.
· Clean the pit periodically and spread the soil on the farm.
The process of levelling the land for agricultural or other purposes is called bench terracing. It is generally done where there is deep heavy clay soil rather than in very sandy soil. The most direct method is called the cut and fill procedure and requires several steps These are:
Area
1. Using an A-frame, mark at least two contour lines on a hillside. The vertical distance should not be more than 1.5 meters. Generally, the vertical distance will be about 1.0 meter. The distance along the slope will vary. The more gentle the slope. the further apart the contour lines.
Find the midline
2. Find the midline between the two contour lines.
3. Using draft animals or hand tools such as shovels, begin removing the soil from the upper half of the strip, i.e., midline to upper contour line (the cut) and place it on the lower half (the fill).
4. Continue the process until the area above the midline and the soil piled below the midline are levelled.
5. The front of the level area called the riser should be constructed so it slants back toward the hillside. The angle of the riser should be between 15° and 45° depending upon the type of soil and the riser height. The angling of the riser will give it more stability. Further riser stabilization is done by planting the riser with grasses.
6. A small canal is excavated at the base of the terrace. This canal is used to carry off excess rain water during heavy rains and saves the terrace below from being washed away. Care must be taken to integrate the drainage of the bench terrace into the overall drainage system of the farm
7. Slope the new front area of the terrace slightly upwards. At the front of the terrace and on the top of the riser, construct a small mound or lip. This will prevent water from washing over the front and eroding the riser
Cross section showing riser lip
CONSIDERATIONS:
1. Bench terracing is the most labor intensive and the most expensive of the land-levelling processes and often requires draft animal power.
2. A scraper/scoop can be used to help in moving soil. The scraper consists of blade made of a solid plank of wood or metal with a handle attached and a strong rope (4 m. length) attached to the top of the blade (base of the handle). The scraper is operated by two men. One places the blade into cultivated soil. The other, guided by the man with the handle, pulls the scraper towards the fill area. If draft animals are available, the area can be plowed first to facilitate soil movement. The blade can be attached to and pulled by draft animals.
Two-man scraper
3. Frequently, top soil from the proposed terracing areas is removed and stock piled on the side. The base of the bench terrace is constructed using subsoil from the cut area and then the top soil is placed back on the surface. The process is time consuming but ensures good will remains on the surface.
4. Several different materials may be used to stabilize the riser. These include Bermuda grass Cynodon sp.,Napier grass Pennisetum purpureum, "Hetero", Desmodium heterophyla.
5. In some areas of the country, legume hedgerows are placed at the top of the riser and constantly pruned to generate green manure or animal feeds. vetiYer grass may also be planted on the lip.
Legume hedgerow on terraces
6. Rockwalls are frequently used to create a more permanent riser. (See Terraced Land Agncultural Technology, page 81.)
7. To protect the above newly terraced area, a drainage canal can be constructed across the top of the farm and excess water from land above the farm can be diverted around the farm. Care must be taken to stabilize the canal and the gully into which the water flows. This is especially true on steep slopes.
8. Care should be taken that a finished riser height is not too tall. When one terrace is linked to the one below it, the riser height is the same as the vertical distance between contours. Riser heights of over one meter are difficult to climb. For example, if the vertical distance between contour lines is 20 meters, the riser height of one terrace is 10 meter.
This is fine until another bench terrace is built above or below. If the new riser also has a 2.0 m vertical height between contours, the common riser between the two benches will be 2.0 m. A farmer would need a ladder to climb over the riser. It would ' he more unstable because of its height.
A riser is too high
9. The bench terrace requires maintenance. The canal at the back should be constantly cleaned, the riser checked and its cover maintained, If hedgerows are present, they should be regularly pruned.
10. Comparison of bench terracing with other soil conservation structures:
Figure
11. Rockwalls are sometimes used to stabilize the riser and the terrace used for both wet land and dry land crops. (See Terraced Agricultural Land Technology)
TERRACED AGRICULTURAL LAND TECHNOLOGY (TALT)
This farm technology was observed in Patlabawon. Patnongon, Antique, and dates back to the early 1900s. In some parts of Cebu, this practice has likewise been observed. A more extensive proof of this technology is the irrigated rice paddies of the Cordillera, particularly the Banaue rice terraces.
Materials include stones or rocks, A-frame, carabao or cow, plow, flat bar, pick mattock, hoe, spade or shovel, wooden plank.
Procedure:
1. Locate a site with good soil and where stones/boulders are abundant
Plow line on hillside at soil height
2. Establish the contour using an
A-frame
3. Collect stones/rocks and prepare
them below the identified contour line
4. Plow and dig the identified contour deep enough to accomodate the initial foundation of big stones. Set the initial stones on angle towards the slope.
5. Pile rocks stones gradually in a manner that they fit and lock each other. Fill in the gaps with smaller stones and clayey soil to minimize leakage. The heavier end of the rock or boulder must be piled facing the hill for greater stability. The base of the rockwall must be always wider than the top. The inclination of the rockwall should be between 5-10 degrees from the vertical axis.
6. Plow to loosen the upper portion of the slope and move the soil using a harrow mounted with a wooden plank towards the rockwalls if soils are deep.
7. After attaining the desired level of the soil, construct a dike on the soil surface adjacent to the top of the rockwall. This will create a holding area for water.
8. Terrace building starts from the bottom and proceeds uphill. In severely eroded areas like Cebu, the farmers start building from the upper slope.
9. Prepare the field for planting of rice during rainy months and corn/tobacco/vegetables during summer.
10. Plant forest and fruit trees on the upper portion of the hill and some leguminous species around the terraced area to minimize soil erosion and enhance water accumulation.
CONSIDERATIONS:
1. The distance between contour lines depends on the farm plan and the farm situation.2. The height of the rockwalls depend on the availability of stones/rocks in the area, farm situation and farm plan.
3. This labor intensive technology is best done through alayon or dagyaw (bayanihan) or mutual labor sharing (man and animal).
4. To break big stones, heat and pour tap water over the rock before breaking with pick mattock.
ESTIMATED COST OF CONSTRUCTION OF TERRACED RICE PADDY
1. Construction of Rock walls (Gathering and Piling of Rocks) Rockwall Dimension:
1.0 meter base
1.0 meter high
0.5 meter top
Rate: 2 linear meters per person day2. Diversion of Soil a. Average of 2 cubic meters per person day b. Average of 8 cubic per person/animal day at P15 00/cubic meter
3. Leveling the Rice Paddy 112 Hectare per person/animal day
4. Construction of Paddy Dikes (Dimension 30 × 60 cu m)
Average of 9 linear meters per person day
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