Terracing (traditional ways of controlling soil erosion)

The traditional farming practices employed on steepy sloping land in mid-hills led to soil and water erosion and low crop and fodder yields. The People started work to identify and test an integrated approach for addressing these constraints. The approach taken was an improved hill terrace for rainfed conditions consisting of structural and vegetative measures.

In Nepal, we see the hills and mountains carved into terraces all throughout right from the ancient past. Our ancestors learned the necessity of saving soil from erosion long before modern agriculture developed such practices. They learned this as an art and it became part of our culture. The people of Nepal truly love their land, where families have held fast to the land for generations.

Terraces are level or gently sloping platforms constructed across the slope and supported either by mechanical (such as retaining walls) or vegetative barriers and designed to make the land suitable for cultivation and prevent accelerated erosion. 

The objective of terracing is:

·         To reduce run-off and retard soil erosion.

·         To make sloping operations possible and safe on slope land.

Thus, the objective of terracing is to use sloping lands more intensively without causing soil erosion that would otherwise be possible. The objective is achieved by: ·

·         Decreasing the length of slope over which the surface water runs,

·         Intercepting the run-off before much of it can accumulate and carry it to the safe outlet.

Types of Terraces

Bench Terrace

Bench Terrace is the oldest terrace. For several thousand years, bench terraces have been widely adopted over the world, particularly in Europe and Asia. The bench terrace is built by placing a wall of earth or stone along the contour and either filling the space above this wall or allowing it to be filled by erosion. They are in a series of level or nearly level strips across the slope supported by steep risers. The risers are usually protected by grasses. Erosion remains a serious problem, especially if the risers are not stabilized and run-off water is allowed to concentrate. The risers should be planted with deep-rooted grass to hold it in and prevent erosion. The bench or floor of the reverse sloped terrace (inward sloped terrace) should be placed inward towards the toe. The excess rainfall will flow towards the toe and be carried off in a small ditch to a safe outlet. 

Sloping Agricultural Land Technology (SALT)(Modern ways of controlling soil erosion)

A common problem in sloping agricultural land 

Degradation of land 

Topsoil erosion leading to nutrient loss

Decreasing crop yield 

Increasing food insecurity 

History

This technology originated in the Philippines as a result of problems faced by upland farmers of Davao del Sur, Mindanao Island. The major problem faced by these farmers was low and gradually declining farm income. Studies suggest that in just 10 years, the maize yield declined from 3.5 t/ha to 0.5 t/ha. The same scenario was observed among other crops. The yield of many crops has declined by 60 to 80 percent within a short period of time. Due to this low and declining farm income, farmers have to search for efficient alternatives. So, some farmers started to cultivate permanent crops. However, in these crops yield was also low. Later after several studies, it was known that the loss of soil and nutrients from the soil was the major reason behind the declining yield of the crops. Also, farmers were in search of better distribution of crops that would supply produce and income throughout the year as their traditional farming is able to supply yield and income in seasons only. They have to face the problem of hunger and money during the off-season.

The Asian Rural Life Development Foundation (ARLDF) working for the holistic development of farming communities in hilly areas felt the problems faced by the farmers and worked several years to develop technology that could minimize the soil loss and increase productivity by improving soil fertility. Later in 1971, they conceptualised the new farming technology which is named Sloping Agricultural Land Technology (SALT).

INTRODUCTION OF SALT

Sloping agricultural land technology (SALT), otherwise known as contour hedgerow intercropping (agroforestry) technology (CHIAT), is a system in which dense hedgerows of fast-growing perennial nitrogen-fixing tree or shrub species are planted along contour lines thus creating a living barrier that traps sediments and gradually transforms the sloping land to terraced land. The nitrogen-fixing hedgerows lining the terrace help improve soil fertility through nitrogen fixation at the roots and incorporation of the hedgerow trimmings into the soil. The hedgerows both markedly reduce soil erosion and contribute to improving and/or maintaining soil fertility The Mindanao Baptist Rural Life Center (MBRLC) is a small, Church-related non-government organization with a 19-hectare demonstration farm located in the rolling foothills of Mt. Apo, the highest mountain in the Philippines internationally known by the name of its sister affiliate Asian Rural Life Development Foundation (ARLDF). It has emphasized upland development since it began in 1971. The technology was verified in 1978, on a marginal site in Kinua Kusan Mindanao Island, in the Philippines. In Nepal, it was introduced in the Himalayan region by ICIMOD in 1992.

Characteristics Of SALT

The SALT system must;

•Adequately control soil erosion,

•Help restore soil structure and fertility

• Be efficient in food crop production,

• Be applicable to at least 50 percent of hillside farms,

•Be easily duplicated by upland farmers with the use of local resources and preferably without making loans,

•It must be culturally acceptable,

•Have the small farmer as the focus and food production as the top priority,

•Be workable in a relatively short time,

•Require minimal labor, and be economically feasible

•It is easily replicable.

•It is ecologically sound

•Fast-growing nitrogen-fixing trees are grown along the contour line to form the hedgerows that serve as the barrier and entrap the sediment and by the time it converts sloping land to terrace land.

•It is a proven technology for controlling soil erosion in the mountainous region.

•Timely pruning of contour hedgerows is practiced. Pruned foliage, branches, and other parts are used as fodder for livestock and as fertilizer for field and forage crops.

Ten Steps of Salt

SALT is an improvement over existing technologies. It is a simple, effective method of farming uplands, without losing topsoil to erosion (MBRLC 1988). It consists of the following ten basic steps:

1. Making the A-frame: The A-frame is a simple device for laying out contour lines across the slope. It is made of a carpenter level and three wooden or bamboo poles nailed or tied together in the shape of a capital letter A with a base about 90 centimeters wide. A carpenter's level is mounted on the crossbar.

2. Determining the contour lines: One leg of the A-frame is planted on the ground, and 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 frame's rear (first) leg. The process is repeated across the field. The contour lines should be spaced 4 5 m apart.

3. Cultivating the contour lines: One-meter strips along the contour lines should be plowed and harrowed to prepare for planting. The stakes serve as a guide during plowing.

4. Planting seeds of different nitrogen-fixing trees and shrubs: Along each prepared contour line, two furrows should be laid out. Two to three seeds are planted per hill, with a distance of 12 centimeters between hills. The seeds should be covered firmly with soil. When the hedgerows are fully grown, they hold the soil and serve as a source of fertilizer. Examples of suitable hedgerow species are Flemingia macrophylla (syn. congesta), Desmodium rensonii, Calliandra calothyrsus, Gliricidia sepium, Leucaena diversifolia, and L. leucocephala (see Appendix).

5. Cultivating alternate strips: The space between the rows of nitrogen-fixing trees on which the crops are to be planted is called a strip or alley. Cultivation is done on alternate strips (strips 2, 4, 6, and so on). Alternate cultivation prevents erosion because the unplowed strips will hold the soil in place.

6. Planting permanent crops: Permanent crops such as coffee, cacao, banana, citrus, and others of the same height may be planted when the nitrogen-fixing species are sown. Only the spots for planting, however, are cleared and dug, and later only ring weeding is employed until the hedgerows are large enough to hold the soil in place. Permanent crops are planted in every third strip. Tall crops should be planted at the bottom of the farm while short ones are planted at the top.

7. Planting short-term crops: Short and medium-term income-producing crops (pineapple, ginger, taro, sweet potato, peanut, mungbean, melon, sorghum, corn, upland rice, etc.) should be planted between the strips of permanent crops as a source of food and regular income while farmers are waiting for the permanent crops to bear fruit.

8. Trimming of nitrogen-fixing trees: Every 30 to 45 days, the growing hedgerows are cut to a height of 1.0 to 1.5 m from the ground. The cut leaves and twigs should be piled on the soil around the crops, where they serve as an excellent organic fertilizer. In this way, only a minimal amount of commercial fertilizer (about 1/4 of the total fertilizer requirements) is necessary.

9. Practicing crop rotation: A good way of rotating is to plant cereals such as corn or upland rice, tubers, and other crops on strips where legumes 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, such as weeding and pest control should be carried out regularly.

10. Building green terraces: To enrich the soil and effectively control erosion, organic materials such as straw, stalks, twigs, branches and leaves, and also rocks and stones, are piled at the base of the rows of nitrogen-fixing trees. As the years go by, strong, permanent terraces will be formed which will anchor the precious soil in its right place.

Different systems/types of SALT technology

1.SALT-1: (Sloping Agriculture Land Technology) This model focuses mainly on food crop production; it is simple, applicable, low cost, but effective agroforestry in a ratio of 75:25. Based on the experiences of MBRLC/ARLDF, this technology decreases erosion substantially compared to the traditional, upland farming management practices. In addition, it increases crop yield 5-6 fold.

2. SALT 2: (Simple Agro-Livestock Land Technology) is a small, livestock-based agroforestry system (preferably with dairy goats) and has a land use of 40% for agriculture, 20% for forestry, and 40% for livestock. As in a conventional SALT project, hedgerows of different nitrogen-fixing trees and shrubs are established on the contour lines. The manure from the animals is utilized as fertilizer both for food and forage crops.

3. SALT : (Sustainable Agro-forest Land Technology) is a cropping system in which a farmer can incorporate food production, fruit production, and forest trees that can be marketed. The farmer first develops a conventional SALT project to produce food for his family and possibly for livestock. On another portion of land, he can plant fruit trees such as rambutan, durian, and lanzones between the contour lines. The plants in the hedgerows should be cut and piled around the fruit trees for fertilizer and soil conservation purposes. A small forest of about 1 ha will be developed in which trees of different species are grown for short-range production of firewood and charcoal. Other species that would produce wood and building materials may be grown for medium and long-range production. In some areas where the soil is too steep for row crops, contour lines may be established two or three meters apart and planted with Flemingia or some other suitable hedgerow species. In between the hedgerows, coffee, cacao, calamansi or other permanent crops could be planted.

SALT 4: (Small Agro Fruit Livelihood Technology) is based on a half-hectare piece of sloping land with two-thirds of it developed in fruit trees and one-third intended for food crops. Hedgerows of different nitrogen-fixing trees and shrubs are planted along the contours of the farm.

 

Table: Land use characteristics of different SALT systems

Sloping Agriculture Land Technology Benefits

SALT is the proven technology of upland farming. It has many advantages over the conventional farming practices. The following are the main benefits of Sloping Agricultural Land Technology:

• Sloping Agriculture Land Technology is a simple technology. There is no need for expertise. Any farmer can easily learn to make a contour line by using A frame.

• Low cost method of upland farming.

• It technology helps to maintain the soil structure.

• This technology is best suited for resource poor farmers. Farmers with few tools, little capital and with little formal education in agriculture can easily adopt this technology.

• By preventing soil erosion and retaining moisture, contour farming boosts productivity.

• Planting of Nitrogen fixing trees helps to replenish soil nutrients and ultimately boost up productivity.

• Since we cultivate permanent crops, short and medium term crops in the strips, so crop produce can be obtained year round.

• This technology enables farmers to cultivate varieties of crop at a time.

• The trees and shrubs can be harvested to obtain firewood.

• It can easily revert back to forest land if left unfarmed.

• This technology is applicable to at least 50 percent of hillside farms.

• As the farming technologies adopted by this method are in harmony with the Asian beliefs, it is a culturally accepted method of farming.

• This technology gives priority to food production.

• It is economically feasible.

• It is ecologically sound.

• This technology is efficient for food crop production.

Sloping Agriculture Land Technology Disadvantages

In addition to its many advantages, this technology also has a few disadvantages. The following are the few disadvantages of Sloping Agricultural Land Technology:

• It is a labour-intensive technology. Activities like contour preparation, plantation etc. require much labor.

• SALT hedgerows occupy significant cropping areas.

• Hedgerows need to be protected from grazing. It too requires maintenance.

• Hedgerows may act as hosts to many pests.

Conclusion

Sloping Agricultural Land Technology is a proven technology for hill farming. SALT incorporates soil conservation measures and food production in just one setting. This technology is based on growing the fast-growing perennial nitrogen-fixing trees and the stripes between them were used to cultivate many short and medium-duration food crops or forage crops. The original SALT technology originated in the Philippines in 1971. This was developed by the Asian Rural Life Development Foundation. However, the original idea has been modified as per requirement and different types of Soping Agriculture Land Technology have been developed. There will not be one system for all the farmers. Based on the requirement of farmers, till now four types of of this technique have been developed. There are four types of land. This technology adopts ten steps for developing sustainable farming methods. These steps include making an A-frame, locating and marking the contour line, contour line preparation, planting nitrogen fixing trees and shrubs, cultivating alternate strips, planting permanent crops, planting short and medium-term crops, trimming nitrogen fixing trees, practicing crop rotation, and building green terraces. This technology is ecologically sound, economically viable, culturally acceptable, and easier to adopt and is gaining popularity in hill farming.

source :

https://guide2agriculture.com/sloping-agriculture-land-technology-salt/