A NEW APPROACH IN WATER USE FOR CULTIVATION ON SLOPING LAND – CASE STUDY IN HOA BINH PROVINCE
11:53 - 15/03/2018
Vietnam is known as the country with three-quarters of the land is hilly, mostly sloping land. In which, the areas with slope over 25% making up 50% of the total sloping land (Figure 1). Although there is a large area and the unique advantage of the natural conditions for the production of specialty crops with high economic value, this kind of land is difficult to exploit and use. Due to lack of productive land, farmers in mountainous re
Traditional perspective of farming on slopes
Source: National Institute of Agricultural Planning and Projection, 2013
Vietnam is known as the country with three-quarters of the land is hilly, mostly sloping land. In which, the areas with slope over 25% making up 50% of the total sloping land (Figure 1). Although there is a large area and the unique advantage of the natural conditions for the production of specialty crops with high economic value, this kind of land is difficult to exploit and use. Due to lack of productive land, farmers in mountainous region have cultivated on soils with slope greater than 10o which is highly eroded and cultivation period is shortened. The farmers can cultivate in 1-2 seasons of short-term food crops or cassava and be deserted (Doanh, 2006). Cultivation mode mainly depends on rain and therefore there is greater risk for agricultural production and people's lives. Agricultural production on sloping land is mostly characterized by fully exploit land and natural resources, self-supply, unstable and unsustainable.
Relations between the slope of the ground and irrigation methods
Because of the complex mountainous terrain, irregular rainfall, large amount of evaporation, strong permeability soils, low flow coefficient, uneven and scattered cultivation areas, the water resources is very limited and it is difficult to allocate water resources and arrangement of on-farm irrigation systems.
Slope relates to selection of irrigation methods and techniques. Flow irrigation techniques such as furrow irrigation, earth ditch irrigation in steep slope terrain are
Table 1: Relation between ground slope and irrigation methods
Furrow irrigation with portable pipeline
Sprinkler, drip irrigation
0 – 0.015
0.015 – 0.01
Source: Khang & Anh, 2009
unsuitable, but sprinklers and drip irrigation is possible to apply. In case of large ground slope, it should not use large irrigation level because it may cause erosion and uneven distribution of moisture.
Collecting and storing water at site combined with drip irrigation - a sustainable development solution to increase value of oranges cultivation on slopes in Hoa Binh province
Cao Phong Town, Cao Phong district, Hoa Binh province is well known with famous brand of Cao Phong oranges, depicted geographical indications. Located on an average altitude of 399m above the sea level with a strongly divided terrain, average terrain slope of 10-15%, geological conditions are favorable for orange cultivation but water holding capacity of soil is poor.
Water sources to irrigate 1,200 hectares of oranges in the town relies on water from Dac Tra reservoir and some natural streams in the area when the irrigation demand has exceeded the capacity of Dak Tra reservoir. On-farm irrigation systems mostly use pipes and pumps from the reservoir to supply water with high cost of investment and 1-2km of distance by farmers. Common irrigation measures for orange now are providing water to the trees by pipes manually and high pressure sprinklers. These two irrigation solutions not only waste water but also require more labor to water, low ability to proactively provide water for trees, causing land erosion and loss of fertilizer, affecting to productivity and quality of oranges.
To overcome these limitations while taking advantage of resources in a reasonable manner, the rainwater harvesting solutions at site have been applied.
Figure 2: Layout of water collection and storage system at site
Source: Thao, 2016
The basic principle of the technology is to take advantage of topography of hilly lands to avoid soil erosion by water collecting ditch systems arranged by contourlines in the garden, to build rainwater collection tanks for initiative irrigation at site and gravity fed irrigation for each orange tree.
Source: Thao, 2016
To supply water to orange trees, drip irrigation system has been used. The basic principle of the system is via the central control system and pressurized water sprinklers, water is supplied to every trees with the same flow, not affected by slope. Users can fully control amount of water to the orange tree from a few liters per tree to thousands liters per tree in one time of irrigation. At the same time, through the irrigation systems, fertilizer and plant protection products can be injected which supports to manage nutrition proactively and efficiently for orange tree.
Mr. Ly Dinh Hung, a farmer in Zone 7, Cao Phong town, was very satisfied after one year applied drip irrigation system for 2.5 ha of oranges and constructed one water collection storage tank of 80 m3, he quoted that: “Previously, it cost much every time I watered the orange because of pumping costs. It was most difficult to bring pipeline to every trees for irrigating, so that I could not manage time to water frequently. It was the same with fertilizing, I can only wait until it rains to give fertilizer to each tree. Many times, after fertilizing, it did not rain, manure was melted and it wasted and it could not be absorbed by plants. Now, I mix fertilizer in tank with water and just switch on the pump. Done! Only about 2 hours, the whole gardens is irrigated. The amount of water to every plants is all the same.”
The potential of a large part of hilly land in Vietnam is not currently exploited to develop specialty crops due to limitations of both investment and technology applying. Thanks to advantage of sloping land area such as large rainfall, seasonal distribution water is favorable to be collected. In other hands, application of drip irrigation system helps to prevent soil erosion, save water and control fertilizer for orange in Cao Phong. Result from combination of the technology indicates this is a new direction in approaching irrigation solutions for agricultural production in sloping land. The results have confirmed that the application of these solutions not only effectively help to solve water scarcity problem but also is a new cultivation solution to help reduce production costs, increase productivity and quality in terms of nutrition composition and aesthetic of Cao Phong orange products.
Khang, T. D. & Anh, N. T., 2009. Irrigation measures for hilly regions. Hanoi: Agricultural publishing house.
Doanh, L. Q., 2006. Sustainable farming on sloping land. Hanoi: Agricultural publishing house