The off-site effect of soil erosion is siltation of dams, rivers and flat lands.
Natural vegetative strips (NVS) are narrow live barriers comprising naturally occurring grasses and herbs. Contour lines are laid out with an A-frame or through the ‘cow's back method’ (a cow is used to walk across the slope: it tends to follow the contour and this is confirmed when its back is seen to be level). The contours are then pegged to serve as an initial guide to ploughing. The 0.3-0.5 m wide strips are left unploughed to allow vegetation to establish. Runoff flowing down the slope during intense rain is slowed, and infiltrates when it reaches the vegetative strips. Eroded soil collects on and above the strips and natural terraces form over time. This levelling is assisted by ploughing along the contour between the NVS - through ‘tillage erosion’ - which also moves soil downslope.
The vegetation on the established NVS needs to be cut back to a height of 5-10 cm: once before planting a crop, and once or twice during the cropping period. The cut material can be incorporated during land preparation, applied to the cropping area as mulch, or used as fodder. This depends on whether the farmer has livestock or not, on personal preference, and on the time of cutting. If the grass is applied as mulch or incorporated, the technology can be considered to be an agronomic, as well as a vegetative, measure.
NVS constitutes a low-cost technique because no planting material is required and only minimal labour is necessary for establishment and maintenance. Some farmers had already practiced the technology for several years before the intervention of the ICRAF (The World Agroforestry Centre) in 1993. ICRAF came to realise that farmers here preferred NVS to the recommended ‘contour barrier hedgerows’ of multipurpose trees- which land users viewed as being too labour intensive. When farmers became organised into ‘Landcare’ groups, NVS began to gain wide acceptance.
Land users appreciate the technique because it effectively controls soil erosion and prevents loss (through surface runoff) of fertilizers applied to the crop. As an option, some farmers plant fruit and timber trees, bananas or pineapples on or above the NVS. This may be during establishment of the contour lines, or later. The trees and other cash perennials provide an additional source of income, at the cost of some shading of the adjacent annual crops.
ទីតាំង: Bukidnon, Misamis Oriental, ប្រទេសហ្វីលីពីន
ចំនួនទីកន្លែងបច្ចេកទេស ដែលវិភាគ:
ការសាយភាយនៃបច្ចេកទេស: ត្រូវបានផ្សព្វផ្សាយត្រឹមតំបន់មួយ (110.0 km²)
តើស្ថិតក្នុងតំបន់ការពារអចិន្ត្រៃយ៍?:
កាលបរិច្ឆេទនៃការអនុវត្ត: 1993; តិចជាង 10ឆ្នាំមុន (ថ្មី)
ប្រភេទនៃការណែនាំឱ្យអនុវត្តន៍៖
| បញ្ជាក់ពីធាតុចូល | ឯកតា | បរិមាណ | ថ្លៃដើមក្នុងមួយឯកតា (ដុល្លារ) | ថ្លៃធាតុចូលសរុប (ដុល្លារ) | % នៃថ្លៃដើមដែលចំណាយដោយអ្នកប្រើប្រាស់ដី |
| កម្លាំងពលកម្ម | |||||
| labour | 1,0 | 15,0 | 15,0 | 100,0 | |
| សម្ភារៈ | |||||
| animal traction | 1,0 | 40,0 | 40,0 | 100,0 | |
| tools | 1,0 | 25,0 | 25,0 | 100,0 | |
| stakes (pegs) | 1,0 | 4,0 | 4,0 | 100,0 | |
| ថ្លៃដើមសរុបក្នុងការបង្កើតបច្ចេកទេស | 84.0 | ||||
| ថ្លៃដើមសរុបក្នុងការបង្កើតបច្ចេកទេសគិតជាដុល្លារ | 84.0 | ||||
| បញ្ជាក់ពីធាតុចូល | ឯកតា | បរិមាណ | ថ្លៃដើមក្នុងមួយឯកតា (ដុល្លារ) | ថ្លៃធាតុចូលសរុប (ដុល្លារ) | % នៃថ្លៃដើមដែលចំណាយដោយអ្នកប្រើប្រាស់ដី |
| កម្លាំងពលកម្ម | |||||
| labour | 1,0 | 36,0 | 36,0 | 100,0 | |
| សម្ភារៈ | |||||
| animal traction | 1,0 | 40,0 | 40,0 | 100,0 | |
| tools | 1,0 | 2,0 | 2,0 | 100,0 | |
| ថ្លៃដើមសរុបសម្រាប់ការថែទាំដំណាំតាមបច្ចេកទេស | 78.0 | ||||
| ថ្លៃដើមសរុបសម្រាប់ការថែទាំដំណាំតាមបច្ចេកទេសគិតជាដុល្លារ | 78.0 | ||||
area competition
biomass as fertilizer (or biomass as mulch)
biomass as fertilizer (or biomass as mulch)
crop area loss, before NVS evolved to cash perennials or fodder grasses
during establishment
biomass was given value
regular pruning
government line agencies and educational institutions
negligible socio-cultural conflicts
គុណភាពមុន SLM: 45
គុណភាពក្រោយ SLM: 8
partly increased water-logging (negligible)
គុណភាពមុន SLM: 40
គុណភាពក្រោយ SLM: 2
important for sustainability
pest sanctuary
spreading from the NVS to nearby areas (especially with cogon grass: Imperata cylindrica)
no actual measurement
