The Viet Namese saying Nhat canh tri, canh vien states that the first profitable activity is aquaculture and the second is agriculture, horticulture or gardening. Integrated farming is a traditional approach to family food production in the poor, rural regions of Viet Nam. The integration of the homelot, garden, livestock and fishpond is called the VAC system (VAC in Viet Namese is vuon, ao, chuong which means garden/pond/livestock pen).
The widespread promotion of the VAC system, referred to as the VAC movement, began in the early 1980s. The importance of small-scale integration was emphasized by the late Pres. Ho Chi Minh in the late 1960s. The objective of the movement was to increase and stabilize the nutritional standard of the rural poor. Because of adoption of the VAC system, the dietary standard of the rural poor significantly improved, particularly in the isolated villages in the high mountainous regions.
This farming system is family-managed, with practically all labour coming from the household. VAC farms can be found in various agroecological conditions, including irrigated lowlands, rainfed uplands and peri-urban areas (Figure 1). Ponds are usually constructed primarily for raising land for the home and garden. Traditionally, the water collected in the de facto pond was used for domestic purposes and to produce aquatic weeds for feeding to pigs. Most pig and other manures are used on field crops, especially rice, although as fish production grows in importance, more is diverted for use there.
It is estimated that 85-90 percent of the rural families maintain a garden and livestock pen, with 30-35 percent of these having fishponds. In many villages, 50-80 percent of families have the full VAC system. Figures show that 30-60 percent of income of most village families may come from the system; in many cases, it may be 100 percent.
The upland VAC system (Figure 2) is usually found in mountainous regions, such as Hoa binh, Son la, Ha giang, Tuyen quang, Thais nguyen and other provinces.
The pond is constructed close to the house so that the domestic and kitchen wastes are drained into the fishpond. The livestock pens and garden are also situated near the pond. The 1 000-5 000 m2 garden includes a variety of vegetables (i.e. green onion, sweet potato, watercress, etc.) and fruits (i.e. banana, orange, peach, apricot, etc.) and other crops, including sugarcane, tea and cassava. This provides a mix of perennial and annual crops.
A portion of the livestock manure is used for manuring the trees and vegetables. Trees are manured once or twice a year; vegetables are manured according to their needs. Pond silt is removed every 3-4 years and used as fertilizer.
Most families keep various animals on the farm, including one or more water buffaloes and cattle, one or more pigs, and several ducks and chickens. The large ruminant animals are allowed to graze or are fed farm by-products. The swine and poultry are usually fed with kitchen wastes, as well as other farm by-products, such as cassava, rice bran, sweet potato, banana trunks and water hyacinth.
The fishpond is usually allocated a more central part of the farm for better management. Pond area ranges from 100-1 500 m2, with a pond depth of about 1 m. Ponds are often drained after the final harvest, usually in February. The pond bottom is kept dry for 1-3 weeks; after which it is cleaned, limed, manured and then filled up with water for restocking. Domestic washings and kitchen wastes are channeled into the pond daily. Animal manure is also applied twice a month at the rate of 0.05-0.15 kg/m2. Three months after stocking, farmers begin to harvest on a weekly basis using small nets and continuously restock and harvest the pond.
Basic features of the integrated VAC system in Northern Viet Nam
The lowland VAC system (Figure 3) is usually found in Ha noi, Hai duong, Hung yen, Ha nam, Nam dinh, Hai phong and other provices.
In the lowland areas of North Viet Nam, the integration of garden, livestock and fish culture is also common. Usually, houses are constructed close to the pond. In sandy regions, the houses are often built at some distance from the pond for hygienic reasons.
The garden is usually small, 400-500 m2. Fruit crops commonly grown include banana, orange, papaya, peach, litchi, longan and apple. In many suburban family gardens, ornamental trees and flowers are planted as a main income source. Vegetables grown include green onion, sweet potato, cress, tomato, cabbage and water spinach. Both perennial and annual crops are planted to provide year-round food to the house and products for the market.
Pond mud is annually removed and used to manure fruit trees; livestock manure is used to fertilize vegetables. Pond water is used for irrigating the garden, especially vegetables.
Most families keep various animals on the farm, including one or more water buffaloes and cattle, one or more pigs, and several ducks and chickens. The large ruminant animals are allowed to graze or are fed farm by-products. The livestock pens for pigs, buffaloes and cows are constructed at the corner of the garden close to the pond. The swine and poultry are usually fed kitchen wastes, as well as other farm products and by-products, such as cassava, rice bran, sweet potato, banana trunks and water hyacinth.
Most families have ponds of 50-400 m2, with different shapes and an average depth of 1.0-1.2 m. Ponds are drained after the final harvest (usually in January/February). The pond is then kept dry for a few days, limed, manured and refilled with rainwater or irrigation water (early rains may start at the end of March.) Domestic washings and kitchen wastes may be channeled into the pond with a small part of the manure coming from the livestock used to manure the pond (according to the farmer's experience). Leaves of legumes, such as peanuts, green beans, etc., are also used for manuring the ponds.
Issues for further consideration
In recent years significant improvements have been made to the VAC system with significant increases in fish yield. In upland areas, farmers have also been able to manage stream flows and make them pass through series of VAC ponds where significantly higher fish yields are achieved. The improved practice has potential for application in several other countries in the region, where farmers have relatively small farm holdings.
Human waste is a critical agricultural input in the VAC systems, aside from on-farm produced livestock feed, particularly rice bran and sweet potato. The complementary linkage of all farm components can best be studied with a cropping calendar that includes fish, rice, livestock and other crops.
The lowland systems are significantly different from the upland systems in terms of resource availability and use. Three systems are distinguished: (a) suburban, (b) intensive (i.e. rice production) and (c) lowland (i.e. floodprone environments).
The VAC systems are traditional and farmers and researchers have developed more intensive approaches over the last decade, since economic changes have taken place. They are less specific in their application requirements than Chinese systems presented in this volume. Recent research efforts should be summarized quantitatively to reflect present levels of benefits.