Khun Lean Hak
Water hyacinth (Eichhornia crassipes) is collected during the monsoon floods, attached to poles on the flooded fields, chopped when the water recedes and used as mulch to plant different crops.
This mulching technique is used at the riverside of the Tonle Sap River. The area is flooded during the late rainy season (September to November), and alluvial mud is deposed on the fields, which enhances the soil fertility. The deposition of sediments depends on the extent of the yearly flood, and is threatened by the construction of hydropower dams on the upper Mekong River (Thomas et al. 2012:49), as well as climate change (floods tend to be smaller or more extreme). During the dry season (approximately from January to June, depending on precipitation patterns) the land dries and due to high temperatures and very low precipitations, crops can be harmed.
At first, the farmer gathers the water hyacinth with his boat during the wet season. He surrounds them with a net and pulls them to his fields, where he prepares fences with bamboo poles and iron wires. He fills the fenced area with the water hyacinth. Once the water recedes, he sprays glyphosate on the water hyacinths and chops them by using a hand tractor. He plants his first crop, watermelon, as soon as the soil is dry enough (start of dry season). The crop residues of the watermelon are left on the fields, and he can plant a crop of corn and a crop of cucumber before the next flood enters.
The analyzed area is flat (slope < 2%), tropic (dry and wet season), and the soils are mostly loamy. The groundwater table is rather high with 1-2 m during the dry season (November to May). The area is flooded during and after the wet season (August-September to November). The floods bring sludge and thus nutrients to the fields.
Due to climate change, the rainfalls are more erratic, temperatures rise and droughts are more recurrent. Chili is the cash crop predominantly grown in the flooded area, with floating rice as second crop.
Agricultural activity in this region is confronted with high migration rates (garment industry, cities, or other countries). This is detrimental for the farmers, since there is less labour force available. Also, the presented technology requires a rather high initial investment (especially when a tractor is bought) and an increase of physically strenuous labour. Therefore, the interviewed land user stated that most farmers are reluctant to do high investments on their farm. This is aggravated due to the fact that taking up credits might increase the dependency of the farmer.
- < 0.1 平方千米（10 公顷）
Total area covered by the SLM Technology is 0.02 km2.
2010 through SOFDEC
年作 - 具体指明作物:
- 谷物类 - 玉米
- 蔬菜 - 香瓜、南瓜、南瓜或葫芦
Longest growing period in days: 225, Longest growing period from month to month: Mid-December to end of July
He plants his first crop, watermelon, as soon as the soil is dry enough (start of dry season). The crop residues of the watermelon are left on the fields, and he can plant a crop of corn and a crop of cucumber before the next flood enters.
Major land use problems (compiler’s opinion): Regular flooding, use of pesticides, low soil organic matter, monocultures.
Major land use problems (land users’ perception): Pumping machines and tubes to irrigate are not easily available. High irrigation need as the soil organic matter content is low.
Type of agronomic measures: mulching, minimum tillage
Main causes of degradation: soil management (Soil is left bare (not covered) in other cultivations), education, access to knowledge and support services (People don’t know about cover crops, or are afraid of the initial costs of machinery)
Secondary causes of degradation: crop management (annual, perennial, tree/shrub) (Only annuals are planted, soil is otherwise left bare. But many perennials cannot grow because of the yearly floods), change in temperature (Climate change causes higher evaporation because of higher temperatures.), labour availability (Innovations are becoming more risky as labour availability is decreasing)
Top Right: during the flooded season, water hyacinths are gathered and attached over the fields.
Bottom right: after the floods, the water hyacinths are killed with herbicides (1) and chopped with a hand tractor (2).
Bottom and top left: Different crops follow each other, in this case water melon (3), corn (4) and cucumber (5). The crop residues are always left on the fields.
Technical knowledge required for field staff / advisors: moderate
Technical knowledge required for land users: moderate
Main technical functions: improvement of ground cover, increase in organic matter, increase / maintain water stored in soil
Secondary technical functions: control of raindrop splash, improvement of surface structure (crusting, sealing), increase in nutrient availability (supply, recycling,…)
Material/ species: Water hyacinths
Quantity/ density: n/a
Remarks: As much as the land user can keep with the bamboo poles and wires.
Quantity/ density: n/a
Remarks: Sometimes, the land user tills before the yearly floods due to time issues.
Stefan Graf, Switzerland
|施工材料||wires and bamboo poles||ha||1.0||30.0||30.0||100.0|
|1.||Collecting water hyacinth and put poles||During the floods each year (Oct-Nov)|
|2.||Spraying herbicide on the water hyacinth||After floods|
|3.||Chopping the sprayed water hyacinth with the hand tractor||After spraying herbicide|
Machinery/ tools: Hand tractor with a chopper
The costs were calculated per ha, in 2014. There is only one farmer (2 ha) next to the Tonle Sap applying this technology.
The factor affecting the costs the most is the availability of cheap equipment. For the recurrent activities the labour costs were calculated as if he hired someone, but he does all by himself. The work is strenuous, as he has to walk in water and trough the water hyacinths.
- < 250毫米
- > 4,000毫米
Thermal climate class: tropics. 27-35°C
- 0-100 m a.s.l.
- 101-500 m a.s.l.
- 501-1,000 m a.s.l.
- 1,001-1,500 m a.s.l.
- 1,501-2,000 m a.s.l.
- 2,001-2,500 m a.s.l.
- 2,501-3,000 m a.s.l.
- 3,001-4,000 m a.s.l.
- > 4,000 m a.s.l.
- 非常深（> 120厘米）
Ground water table: during wet season
Availability of surface water: during wet season
Land users applying the Technology are mainly common / average land users
Difference in the involvement of women and men: The labor is strenuous and is therefore mainly done by males. However, the interviewed land user is so far the only one applying this technology in the area.
Population density: 10-50 persons/km2
Annual population growth: 0.5% - 1%
Off-farm income specification: Wife owns a little coffee shop.
- < 0.5 公顷
- 0.5-1 公顷
- 1-2 公顷
- > 10,000公顷
Many land users have a land title that is not recognized by the state.
According to the farmer the yield doubled.
Grows other cash crops than the other farmers in the area.
However, there is less irrigation work needed.
Herbicide is used in the river.
Problems with insects
Herbicide goes into the river
The mulch would be carried away in case of extreme floods, but the technology is dependent on the yearly flood
A hand tractor could be rented instead of bought
100% of land user families have adopted the Technology with external material support
1 land user families have adopted the Technology with external material support
The land user received the money from banks, micro-finance institutes and NGOs. Farmers are afraid of the investment costs. Farmers are afraid of the investment costs and the increased workload.
|It is easy to keep the water hyacinth on the fields after the floods|
|The soil keeps the water, less loss due to evaporation. He uses less water for irrigation|
|The plants grow better and have higher yields|
|The soil is covered, so it needs less irrigation.|
|The land user needs less fertilizer as the soil fertility, biological activity and carbon content is higher.|
|The profit is not in relation to the work.||Plant more profitable cash crops; share the machines with other farmers.|
|The soil is too wet after the floods because the mulch stops the evaporation.||Grow a water loving plant as first cash crop.|
|Only physically strong people can do the work.||Build simplified water hyacinth harvesting structures.|
|Herbicides are used in an aquatic environment.||Find a chopping device that is sufficient to kill the water hyacinth on its own.|
|The initial investments are high.||Tractor bank could be implemented (share the cost of the machines amongst members.)|
Thomas, T.S., Ponlok, T., Bansok, R., et al. 2012. Cambodian Agriculture: Adaptation to Climate Change Impacts. A Report for USAID.