Land and cassava crop in Vietnam
1.1 Land cassava
The largest area of alluvium group deltas (Inceptisols) are found mainly in the Mekong Delta and the Red River. Entisols land is found mainly along the river and the coastal plain, on the different areas of land in nature. In Vietnam, about 66% of cassava is grown on Utisols, 17% on Inceptisols, 7% on Oxisols, 4% on Alfisols, 3% and 2% on Vertisols Entisols (Howeler, 1992).
Land and cassava crop in Vietnam
Cassava is grown in Africa for cassava plant is capable to withstand harsh conditions such as poor soil, acidic soil, arid land, land with aluminum content, high manganese crops More difficult to grow and harvest. Good conditions for cassava growth and development is the average light soil, good drainage, pH 4.5 to 7.5. Cassava plant is adapted to semi-arid conditions, cassava need adequate soil moisture during the growing mainly, after germination can withstand drought for months. Cassava has the ability to adapt to very acidic soil with a high level of Al exchange, adapt to low levels of phosphorus but requires K is high, especially when planting cassava for many years in the soil K levels are depleted masterpiece. Cassava hypersensitive reaction when Zn deficiency symptoms usually appear and Zn deficiency in the early stages of development.Optimal requirements for the development of cassava are: Al exchange of <80%, phosphorus> 5 ppm; Ca exchanger> 0,25 me / 100 g of dry soil; K exchange> 12:17 me / 100 g of dry soil; Na exchange <2.5% saturation, (R. Howeler, 1981).
In northern Vietnam about 68% of the land rocky hills for cassava, Approximately 12% - 18% clay and sand. Popular hilly land in Hebei Province, Ha Son Binh, Phu Tho, Yen Bai and Lao Cai. Cassava is grown mainly in areas where the terrain is mountainous and midland. Approximately 89% of cassava in northern Vietnam are grown on soils above (Pham Van Bien etal, 1996).
In southern Vietnam, most cassava is grown on sandy soils in coastal areas of Central and Southeast regions, while dominant in Gia Lai - Kon Turn and Dak Lak. Cassava growing areas in the Central Highlands provinces have similar topography. Central Coast region and Southeast region, cassava is grown mainly in the gray soil, a handful of red basalt soil or sandy soil. The flat areas, poor soil nutrients and is not suitable for rice cultivation. Cassava planting area of land above categories accounted for over 70% of the total floor area of the South. In the Mekong Delta, cassava is not a major crop. However, cassava grows well in acidic soil in the Mekong Delta in the conditions of high nitrogen (N), potassium (K) and organic matter (OM) average. Cassava is not seriously affected by the toxicity of aluminum (A1) when grown in this soil. With the significant differences of soil properties of cassava, the research in the North should focus on issues of erosion and improve soil fertility, while studies on the south to land reclamation and protection cassava N using intercropping systems is the highest priority
1.2 Time for planting cassava in Vietnam
In our country, cassava is cultivated in all the ecological zones with the natural conditions are very different.Differences in natural conditions also led to a change in the seasonality of cassava appropriate for each region.
In the northern provinces (plains and midlands Tonkin), cassava is grown in February to March and harvested in December to January the following year.
North Central region, cassava is grown in January,
South Central region, cassava can be grown in about 1-3 months, 1-2 months, but earlier planted along harvested in September, in October before the flood season.
Central Highlands, Southeast and some high ground pins of the Mekong Delta (MD), cassava grown mainly in the late dry season and the rainy season (April-May) in conditions of high temperature stability and there are rains. Some places farmers continue to grow cassava for 6 months to March 7. The conditions where the water in the Delta initiative, cassava is often grown up from the beginning in order to harvest before the flood season. Cassava planting season varies according to the specific conditions of each locality but harvest time can start to be 8-10 months after planting. Planted to cassava flour production are usually harvested after 10-12 months. The sweet cassava varieties grown for fresh eating, you can harvest scattered from 6-9 months.
2. Some properties of soil capable of growing cassava in Vietnam
Vietnam's land closely associated with the terrain. The mountainous regions of Northern and Central mainly Ultisols with some Oxisols in the southern provinces.
Vietnam has a tropical climate, located between latitudes 8.5 0 and 23.5 0 North; 102 0 110 0 east longitude.Narrowest place is only 40 km wide (Quang Binh). East Sea to the east, the west of Truong Son mountain range. Varied terrain and sloping down toward the sea to the west - north - east - south. This leads to significant differences in soil and climate conditions across regions. According to the terrain and climate the country was divided into seven regions different agroecological:
Midlands and Northern Mountains;
Red River Delta;
North Central Region;
South Central Coast,
Highland;
Southeast region;
Mekong Delta region;
Howeler (1992) suggests that 66% of Vietnam's cassava is grown on land Utisols, 17% in land Inceptisol, 7% in Oxisols land, land Alfisols 4% in the rest of the earth and Entisols and Vertusols. Much land Inceptisols Ultisols and is characterized by light mechanical composition, pH acidity and organic matter content and low nutrient. According to the survey results of Pham Van Bien, Hoang Kim, Howeler (1996) over 1078 farmers in 45 districts of cassava in the region's main cassava in Vietnam in 1990-1991, with 59% of cassava is grown in sandy soil , 25.3% on rocky land, 11.7% on heavy loams and 3.9% on the soil. About 45% of the cassava was planted on slopes.
Cong Doan and Deturk Iron (1998) compare the physical properties and chemical properties of soil Haplic Agrisosl (Utisols) in the Southeast region under the forest canopy and rubber crops, sugarcane, cashew, cassava for years. They found that planting cassava for years with clay components, structural durability and low water holding capacity, low permeability in the second and third high bulk density. This shows a degradation of soil physical properties due to continuous cropping. On the other hand, cassava land degradation are also about to be calculated is represented by organic matter content, total N, CEC, K, and Mg low exchange. Cassava phosphorus in higher land and forest land under cultivation, but lower than in the land of rubber and sugar cane land. This was due to phosphate fertilizers for cassava, rubber and sugarcane.Nguyen Tu Siem and Thai Version (1993) reported a similar decline in the land of OM, N, Ca and Mg, but no significant reduction in phosphorus cassava over two years when compared to the original forest land Phu Quy in 1994.
3. The area under cassava agro-ecological region of Vietnam.
Cassava has a high adaptability in Vietnam and is grown across 7 regional focus agroecological Vietnam, but concentrated mainly in five major areas are shown in Table 1.
Total floor area of the ecoregion 5 accounted for approximately 97% of the national cassava, (Table 1) is equivalent to 483 thousand hectares, the corresponding output is 8330 thousand tons, accounting for 98% of total national production of cassava. Among them, the most concentrated cassava is grown in the North Central, South Central Coast and Highlands, an area corresponding to 31% and 27% of the total area of the national cassava production reached 2607 thousand tons respectively (31 %) and 2,180 thousand tonnes (26%).
In the South East region has an area of cassava No. 4 of the 5 largest cassava-growing areas throughout the country but the region has the highest yield averaged 25.3 tons / ha, 2nd cassava production, with a total output of 2.28 million tons in 2010, equivalent to 27% of national cassava. Highlands is an area with growth highest cassava growing area in the period of 10 years from 2001 to 2010, up to 14% per year, the second is the North Central region and Central Coast with growth the annual average growth of 6% this period. The province has the largest area of the country cassava Order today include Gia Lai (63.4 thousand ha), Xining (45.7 thousand ha), Kon Tum (41.7 thousand ha), Dak Lak ( 31.8 thousand ha).
Vietnamese
English
