Contour Hedgerow Technology or Contour Hedgerow Intercropping Technology is a set of agroforestry techniques and practices where food crops are planted between hedges of nitrogen-fixing woody perennials along the contours of sloping upland areas. This technology primarily and in long term focuses on conserving soil from erosion and deterioration of its nutritional quality. When managed properly the otherwise sloppy land used for fodder purposes can provide a valuable source of stable crops, fodders, fuelwood, and even cash crops. This technology also contributes to land productivity improvement and bio-terrace formation.
The technology is highly recommended by the FAO as well as other organizations for mid-hills of Nepal with natural slopes and ridges, prone to landslides and slope instability due to intensive cultivation and cropping without any terraces and bunds. The measurements regarding sedimentation and soil loss of the Himalayan region exceed the world average by almost twice the magnitude (Alford 1992). The technology is still in the phase of study and investigation as to whether the cooler climate in Nepalese hills would be suitable for nitrogen-fixing shrubs which were originally studied in the tropical climate of Hawaii and The Philippines. Detailed research could lead to the discovery of optimum conditions and the suitability of plant species that would be best suited for our climate. However, the ICIMOD, with the support of ADB has released a manual of guidelines and techniques to be used that is suitable for the countries located in the Himalayas like Nepal, India, Bangladesh, Bhutan, and Myanmar. With the use of proper hedgerow plants and care and management of the land, bare slopes otherwise prone to erosion and landslides can be converted into prolific and beautiful terraces. The ultimate users and beneficiaries of these technologies are farmers and for the nationwide implementation, the knowledge has to go through researchers and extension workers. Therefore, all three intended audiences should be well trained about the technology.
Experimental field trials conducted by ICIMOD in Godawari, Nepal indicate improvement in various aspects of soil. As of the findings by ICIMOD in 1998,
| Values, compared as 100% in areas w/o hedgerows |
Soil loss | 2nd year | 14.9 to 54.6 % |
3rd year | 4.7 to 22.5% |
Runoff | 2nd year | 75.3 to 94.4% |
3rd year | 72.9 to 85.9% |
| Percentage increment from 1st year |
N content | 2nd year | 14.3-58.2% |
3rd year | 69.3-133.9% |
Organic matter | 2nd year | 4.8-32.3% |
3rd year | 19.8-55.5% |
| Percentage increment from 1st year |
Maize Yield | 2nd year | 17-51% |
3rd year | 30-60% |
Source: ICIMOD, 1998 |
various aspects of soil. As of the findings by ICIMOD in 1998,
Similarly, Flemingia macrophylla, Leucaena leucocephala, Indigofera dosua, Alnus nepalensis, Albizia lebbeck are found to be potentially suitable hedgerows species recommended for the mid-hill areas of Nepal (Ya. T & Murray, 2004). Reports of successful applications of CHIAT (Contour Hedgerow Intercropping Agroforestry Technology) indicate that the easiest way to establish the technology is to use species that have been used successfully elsewhere in regions with a similar environment and climate. However, these species are likely to be exotic species in the new region, and care should be taken. There are Performance and Selection of Nitrogen-Fixing Hedgerow Species (23) increasing reports of ecological problems caused by exotic species which can turn out to be aggressively invasive (weeds) when introduced to a new environment. Two classical cases are those of Eupatorium adenophorum (eupatorium) and Eichhornia crassipes (ICIMOD 2004).
In order for the technology to achieve its potential, other, possibly more appropriate, hedgerow species need to be tested, and more investigations of different crops and their yield need to be carried out to identify optimum combinations for applications in temperate and subtropical areas of the HKH. Contour hedgerow technology is most suited for hills with large slopes and prone to seasonal erosion where human effects of overgrazing and deforestation have led to reduction of quality as well as quantity of soil. This technology benefits the stakeholders in the following ways:
I. The contour hedgerow technology provides a sustainable use of degraded and neglected lands.
II. The primary purpose of this technology is the conservation of soil’s physical, chemical, and nutritional condition.
III. It provides an additional source of food crops, fodders, firewood, and cash crops to farmers.
IV. It forms a bio-terrace that can sustain flora and fauna for a very long period of time even without anthropogenic inputs.
Establishment and care and management of hedgerows
A barren or underutilized site is preferably selected for this technology, having a slope of 3-8%. The contour lines can be marked by constructing an A-frame. An A-frame is a simple tool that can be made easily by farmers with 3 sticks, with a preferred length of 2 sticks of 2m and 1 of 1m.
After the proper calibration of A-frames, points are marked on the hills in a parallel manner at a distance of approximately 4-6 meters. The points are then joined to mark somewhat smooth contour lines. Some off-site points which follow the zig-zag manner can be neglected. After the marking of contour lines, the 60-80cm strip designated for planting the hedgerow plant following the contour lines is finely prepared to ensure proper germination and root growth. Careless and rough land preparation always results in low germination. Therefore, replanting has to be one and this increases the cost
The well-prepared seeds of proper hedgerow plants are then planted in contour lines either by direct seeding, transplanting, or using cuttings depending on the plants used, the distance between two rows being 30-60cm again depending upon the plant species. Application of root growth promoters and chemical fertilizers can be done to help the hedgerow plants in the initial stage of development. One or two weedings are also essential. Replanting and gap filling are carried out to make double hedgerows dense. The double hedgerows are pruned to a height of 50 cm or knee height when they grow 1 m tall. Side pruning is also important. Hedgerow prunings are used as green manures in the upper part of the alley so as to compensate for the downward movement of nutrients in the soil. The alleys can be a source of staple crops, fruits, vegetables, cash crops like Mulberry, fodder trees, and more. This system can also be specialized according to the need of the farmers. For example, Some cash plants like mulberry can be cultivated within the double hedgerows.
Some species provide good fodder which returns manure to the farmland, increasing production. If the hedgerows are used for fuelwood production or poles, sideways trimming is promoted leaving long stems intact. The side prunings and fallen leaves increase soil fertility, as well as fuelwood, are obtained. In the long term, hedgerows form bio-terraces that will naturally reduce runoff velocity, catch sediments and preserve soil nutrients. In general, when establishing Contour Hedgerows, contour lines should be properly located, double hedgerows should be maintained densely, avoid shades falling on crops and hedgerow pruning should be applied in the alleys and not beside the hedgerows.
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