Rice production practices in Viet Nam

RICE PRODUCTION PRACTICES IN VIETNAM

Nguyễn Văn Ngưu

Người ta đi cấy lấy công

Riêng tôi đi cấy còn trông nhiều bề

Trông trời, trông đất, trông mây

Trông mưa, trông gió, trông ngày trông đêm

Trông cho chân cứng đá mềm

Trời yên biển lặng mới yên tấm lòng

Or

Other people transplant to earn a salary

I transplant with much anxiety

Looking at the sun, the land, the cloud

Asking for rain, searching for sign of strong winds, day and night

Wishing that leg be strong, and rock be soft

I will be at peace only if the sky is calm and the ocean peaceful

Vietnamese rice farmers have worked hard and have good experience in rice farming, but farmers know that their work and effort still depend on several factors and they always wish that they would be strong to perform the hard work in rice farming and the weather be favorable for good rice growth and production. Transplanting is one of the activities in lowland rice production, which has been the principal activities of rice production in Vietnam for more than 4,000 years. Although formal schools on farming were established only in early 20th century, Vietnamese farmers have rich experience and knowledge in carrying out these rice farming activities. The following pages describe the different activities in producing lowland rice in Vietnam.

I. The Selection of Time for the Establishment of Rice Crop

It is well established that growth, development and production of rice crop are highly influenced by weather conditions. Timely establishment of a rice crop, therefore, would allow the crop to grow and develop under favorable weather conditions. Under rainfed conditions, the timely crop establishment permits the crop to grow and develop during the period with good rainfall for adequate water supply. Many lowland rice areas in Vietnam are susceptible to annual flooding. Deep and prolonged flood could kill a whole rice crop. In many central coastal provinces, the severe and destructive floods are most likely to take place in October and November (Tran Trong Thuy, 1977). Farmers, therefore, knew that the planting of monsoon rice crop should be made before the 13th solar term or Lập Thu phenomenon that takes place in August and this was expressed in the following Ca Dao.

Lập thu* mới cấy lúa Mùa

Khác nào hương khói lên chùa cầu con

Or

To transplant monsoon (lua Mua) at Lap thu

Is similar to going to pagoda to pray for having a child

* It begins when the Sun reaches the celestial longitude of 135° and ends when it reaches the longitude of 150°. It usually occurs in August.

In the old time, farmer in northern provinces of the country had the habit to look up to the moon and stars in the sky in order to select the date of planting the monsoon rice crop. Through experience, they found out that the period between the first and last appearance of the Tua rua (or Pleiades or Seven Sisters) is best for transplanting the monsoon rice crop.

Tua rua một tháng mười ngày

Cấy tróc vùng cày cũng được lúa xơi

Bao giờ nắng rữa bàng trôi

Tua rua quắt lại thì thôi cấy mùa

Or

Tua rua appears and lasts for a month and 10 days

Transplanting rice would provide rice to eat

When the sun is washed with drift

Tua rua reappears then stop the transplanting of monsoon rice

Farmers in the Red River Delta in the past had the experience that transplanting the Chiem rice crop in January (or tháng Chạp in Vietnamese calendar) produces high yield and they expressed this knowledge as following.

Cấy mạ tháng Chạp chân đạp không ra

Transplanting rice in January feet are tired of threshing*

* tháng Chạp or December in Vietnamese calendar or January in Solar calendar. In the very old times, farmers used their feet to thresh the harvested rice.

In Nghệ An and Hà Tĩnh provinces, the following saying indicates the right time for transplanting rice crop during Chiêm season

Cấy trước Đông Chí vội gì mà lo

Or

Do not worry, you could transplant just before winter solstice*

*  Winter solstice happens on December 22nd in Northern Hemisphere

II. The Selection of a Variety/or Seed to Plant

Farmers recognized that the success in rice production is closely linked to the selection of a variety for planting. Rice variety with erect leaves, short culms and responsive to nitrogen fertilizer would yield high in areas with adequate water supply and high solar radiation. However, in area where water would be available for only 4 months, a rice variety with five months growth duration would produce nothing. Similarly, a non-salt tolerant variety would yield very low if planted in a saline affected field.

In the 16th century, the scholar Nguyen Binh Khiem advised farmers of his plantation that

The last crop has been lost because of bad seeds; for next crop you must pick the old strain”. Vietnamese farmers in general understand the importance of the selection of good variety for planting and they expressed this in the following proverb.

Tốt giống tốt mạ, tốt mạ tốt lúa

Or

Good variety produces healthy seedlings, healthy seedlings produce good rice crop

The Tich Dien Festival (Toan Anh 1997) has been a popular festival since the reign of King Le Dai Hanh (980-1005). The seeds, which were harvested from the fields used in the Festival, were distributed to farmers for planting in the next rice crops. These seeds were normally of high quality because the variety planted in Tich Dien Festival were selected by scientists and experienced farmers and the Tich Dien fields/crops were managed by best farmers with full support in-terms of inputs and water supply from government. The seeds harvested from Tich Dien Festival, however, were of limited quantity for providing to all farmers. In the past, therefore, majority of farmers had to rely on themselves and their neighbors for good seeds. Experienced farmers would select and harvest panilces of heavy seeds a few days before the general harvest of the whole crop. These panicles were separately threshed, cleaned, dried and stored for seeds.

The following ca dao describes the selection of rice variety for planting by farmers in the past.

Tháng Năm cho chí tháng Mười

Năm Mười hai tháng em ngồi em suy

Mùa Chiêm thì cấy lúa Di

Mùa Mùa lúa Dé sớm thì Ba trăng

Thú quê rau cá đã từng

Gạo thơm cơm trắng chi bằng Tám Xoan

Or

In June as in November*

June November the two months I sit and think

For Chiem crop I transplant Di rice

For Monsoon crop the De rice for early rice crop the Ba trang rice

It has been the popular habit of food in the village

Best scented white rice is Tám Xoan

In the present days, majority of farmers selected high yielding or hybrid rice varieties to plant and consequently the area planted to traditional rice varieties has been significantly reduced to about 3.6 to 21.4% depending on locations (Table 1). Today, traditional rice varieties are generally planted to upland area and rainfed areas running along the seashore.

Table 1 Number of varieties and planted areas of High Yielding and Traditional Rice Varieties during Winter-Spring and Summer-Autumn seasons in Vietnam in 2000-2001 (UNEP, 2005)

Winter-Spring Season

High Yielding Varieties

Traditional Varieties

No. of varieties

Planted area (%)

No. of varieties

Planted area (%)

Northern Region

160

96.4

38

3.6

Central Region

116

95.8

13

4.2

Southern Region

167

91.6

21

8.4

Summer Autumn Season

High Yielding Varieties

Traditional Varieties

No. of varieties

Planted area (%)

No. of varieties

Planted area (%)

Northern Region

145

88.5

73

11.5

Central Region

126

78.6

41

21.4

Southern Region

147

95.3

27

4.7

III. The Preparation of Land for Rice Production

Land preparation is a key operation in rice production. A well-prepared field controls weeds, recycles plant nutrients, and provides a soft soil mass for transplanting or suitable soil surface for direct seeding. The conventional method of land preparation in lowland rice production involves (1) plowing to “till” or dig-up, mix, and overturn the soil; (2) harrowing to break the soil clods into smaller mass and incorporate plant residue, and (3) leveling the field. Vietnamese farmers understand that deep plowing provides rice plants with more rooms for growth and development of their root systems and they expressed their knowledge as following:

Cày sâu tốt lúa

Or

Deep plowing produces good rice crop

Farmers also know that good land preparation for rice production requires not only deep plowing, but also thorough harrowing and they said.

Muốn cho lúa nảy bông to

Cày sâu, bừa kỹ, phân tro cho nhiều

Or

If you want rice plant to have large panicles

Plow deep, harrow well, apply good quantity of fertilizers

In the past Vietnamese farmers had experiences the selection of the right wood for fabricating the ploughs and harrowing tools and they expressed as following

Gỗ Kiền anh để đóng cày

Gỗ Lim gỗ Sến anh nay đóng bừa

Or

I use Kiền wood for making the plough

I use Lim wood Sến wood for making the harrow

Farmers also had good knowledge on the appropriate size for fabrication of these tools

Răng bừa tám cái còn thưa

Lưỡi cày tám tấc* đã vừa luống to

Or

Tooth harrow having 8 teeth is still sparse

An eight “tấc” plough is good enough for good tilth

* Tấc is a measuring unit in Vietnam in the past, 1 tấc = 4.7 centimetres

Some farmers in the past practiced Cày Ải or to plow the rice field right after the harvest of the monsoon (or Main) season crop to expose rice soil to the sun during dry season to expedite the oxidation of organic matter and minerals in the soil for improving soil fertility.

Cày Ải còn hơn rãi phân

Or

Cày Ải is better than fertilizer application

The Cày Ải also helps in saving time and water used in the land preparation for the succeeding crop. The amount of water for soaking the soils for plowing is normally large and in rainfed conditions the time to wait for enough rain to soak the soil for plowing is quite long.

Good land preparation and land levelling help in keeping water from rain or irrigation and the layer of water on the field helps to suppress weed germination and growth. Good land preparation also helps in minimizing the vertical loss of water in rice field. The flat lowland rice fields seen throughout the country indicate the farmer’s knowledge and recognition of the importance of good land preparation and levelling in rice production.

In the recent past, in order to strengthen and speed up land preparation for intensification of rice production, Vietnam government has introduced and popularized the use of tractors, both 2-wheels and 4-wheels, in land preparation. In 2001 for example, about 3,012 large tractors (> 12 CV) and 4,566 small tractors (< 12 CV) were used in land preparation for rice production and the total area of rice land prepared with tractors was about 2,526,000 hectares or 63.5% of the total rice land (GSO, 2002).

IV. The Establishment of the Rice Crop

Most of rice fields in Vietnam have been lowland rice fields and in the past transplanting was the popular method of rice crop establishment and farmers had to prepare the nursery beds for grow rice seedlings, pulling the rice seedlings when they are old enough and bring them to the main field for transplanting. During the rainy season, farmers built the nursery bed for monsoon rice crops in June-July at elevated areas to avoid flooding. On the other hand, during dry season, they constructed the nursery bed for Chiem crop in November-December in low lying area near to water ponds, channels and river in order to have irrigation water. Farmers shared this knowledge as following.

Mạ mùa nương cao, mạ Chiêm ao thấp

Or

Seedlings of monsoon crop be at elevated place, seedlings of Chiêm crop be near to a pond

Farmers soak and incubate the selected seeds before seeding them to the nursery beds and they noticed that during Winter (for Chiem crop) the incubated seeds had to germinate well before seeding in order to have subsequent good seedling growth, while during Summer (for monsoon crop) incubated seeds that crack the hull/husk is enough for seeding and subsequent good seedling growth and they expressed this experience as following.

Mùa nứt nanh Chiêm xanh đầu

Or

Monsoon seeds need only to crack the hulls,

While Chiem seeds have to have green heads

During Mua or monsoon season, transplanting takes place in June and July when temperature is generally high the use of young seedlings is generally recommended for good crop growth and development after transplanting. However, during winter-spring or Chiem season when transplanting takes place in January when temperature is low during transplanting, seedling age has little effect on the performance of rice crop. Farmers had the following observations.

Mạ Chiêm ba tháng chưa già

Mạ Mùa tháng rưỡi ắt là chẳng non

Or

3-months-old seedlings are not old for Chiêm crop

45-days-old seedlings are not young for monsoon or Mùa crop

In soils which are clayey or loamy, young and healthy seedlings normally recover quickly after transplanting. However, in sandy soils the loss of water in the fields is rather quick, old and partially wilted seedlings perform better as they are more seasoned to withstand the stress of limited moisture. This observation was described as following.

Mạ úa cây lúa chóng xanh

Gái đồng chóng đẻ sao anh hững hờ

Or

Partially wilted seedlings become green faster

Farm ladies bear child fast why do not you notice

The depth of transplanting affects the subsequent tillering capacity of rice seedlings. Under low temperature, a shallow transplanting would expose the roots of the seedling to cold damage, thus deep transplanting is needed. However, under high temperature, the deep transplanting damages the tiller buds at the base of the seedlings. This experience is described in:

Lúa Chiêm thì cấy cho sâu

Lúa Mùa thi gãy cành dâu là vừa

Or

For Chiem crop one needs to transplant deep

For Mua (or monsoon) crop, transplant just to the base of the seedlings

Similarly, the following saying conveys the same knowledge.

Lúa Chiêm đào sâu chôn chặt

Lúa Mùa vừa đặt vừa ăn

Or

For Chiem crop transplant deep

For Mua crop transplant just to the base of the seedlings

In fields with clayey or loamy soils, it is normally kept undisturbed sometimes after land levelling to allow soils to firm up before transplanting. In sandy soils, however, due to the rapid losses of water, soils become hard quickly after land preparation. In this situation, transplanting must be done right after land preparation. Farmers expressed this knowledge in:

Trâu ra mạ vào

Or

As the buffalo is out the seedlings are in

In the very early period of rice production in Vietnam, most or rice varieties had tall plants, which were easily lodged, farmers were advised to transplant at far distance as in following ca dao

Cấy thưa thừa thóc

Cây dầy cóc được ăn

Or

Transplant sparsely have extra rice

Transplant closely have nothing to eat

After the introduction of modern and high yielding, short stem and lodging resistant varieties the transplanting at right or close spacing produce high yield and farmers transfer this knowledge in the following ca dao.

Cho nhất hàng song

Cho đông hàng con

Cho tròn bụi lúa

Or

Transplanting at straight rows

Transplanting at close spacing between hills

So the crop will be good

Transplanting at close spacing require time and labor. Labor who were hired to transplant know this and they used to bargain as following.

Trả ta đủ gạo đủ tiền

Thì ta sẽ cấy cho vừa hàng song

Ví dù bớt gạo bớt công

Thì ta cấy rộng cho xong ta về

Or

Pay me the right wage

I will transplant at right spacing

If you lower my wage

I would transplant at wide spacing to complete it early

In deep water areas in Mekong River Delta such as in Dong Thap Muoi, farmers in the past practiced double transplanting, which had the following steps: (1) First transplanting – transplant 40 days old seedling at nursery-bed/transplanted area ratio of 7:1 and (2) second transplanting at 60 days after the first transplanting at a ratio of the area of first transplanted area to the second transplanted area of 1:5 (Nguyen Van Luat, 1984). Also, in the Mekong River Delta after the popularization of tractors, water pumps and early maturing varieties, increased number of farmers had adopted direct seeding for crop establishment in order to grow two to three rice crops in a year.

V. The Watering/Irrigating of the Rice Fields

Rice plants consume large amount of water to grow and develop. In the past, farmers recognized the important contribution of rain that supply water in successful rice production. They expressed this in the following proverb (tuc ngu).

Nắng tốt dưa, mưa tốt lúa

Or

Sunshine is good for watermelon, but rain is good for rice

But heavy rains may cause flooding that could destroy rice crop. In the past farmers based on the activities of the swallow to predict the type of coming rain in order to plan needed action to assure good rice production as expressed in following ca dao.

Én bay thấp mưa ngập bờ ao

Én bay cao mưa rào lại tạnh

Or

Swallows flying low, heavy rains would overfill the pond

Swallows flying high, shower will soon stop

In the past when irrigation was still limited, rainfall in October, when rice was at about flowering stage, was very important for rice production as it is expressed in the following ca dao.

Mồng chín (9) tháng chín (9) có mưa

Thì ta sắm sửa cày bừa làm ăn

Mồng chín tháng chín không mưa

Thì con bán cả cày bừa đi buôn

Or

If there is rain on the 9th day of the 9th month

We will prepare tools for rice production

If there is no rain on 9th day of the 9th month

You should sell the rice production tool and engage in trading

Rice yields are closely related to water availability during cropping season and farmers in the past recognized this, as it is expressed in the following tuc ngu.

Nhất nước, nhì phân, tam cần, tứ giống

Or

First is water, second is fertilizer, third is hardworking/industry, and fourth is seed.

It has been established that irrigated rice produces higher yields than rainfed lowland and upland rice. Farmer also said the following.

Không nước không phân chuyên cần vô ích

Or

No water no fertilizer your hard labor would be useless

They valued highly the irrigation work and said that

Một lượt tát một bát cơm

Or

One watering produces one bowl of rice

They also said

Lúa khô cạn nước ai ơi

Rủ nhau tát nước chở trời còn lâu

Or

Rice field has no water

Let us do watering instead of waiting for the heaven

Effort to develop irrigated rice farming practices took place very early in Vietnamese history. As reported earlier in RICE THROUGH HISTORY OF THE COUNTRY, Vietnamese farmers in the VIth century used the power of tide to provide water or irrigate their rice fields (Cima, 1987). In the IXth century, there were three manmade rivers were built in the Red River Delta and they were extended to Thanh Hoa and Nghe An provinces by King Le Dai Hanh, 980-1005 (Bui Huy Dap, 1985). Similarly, many works on digging/building man-made rivers and canals had been carried out by kings during the history of the country. During the southward expansion, the official of the Nguyen Lords had dig and/or constructed number of canals in the Mekong River Delta and this effort was continued by the colonial French government.

On the other hand, farmers had developed gau giai (or swinging baskets), gau song (or scoop), and dragon wheels for water from canal/river to rice fields. The following saying describes appreciation of the work on watering rice fields by farmers population in the past.

Nắng chiều, lúa nghẹn, anh ơi

Mình lấy sức người chống lại thiên tai

Mấy anh tát một gàu giai

Chúng em hai đứa tát hai gàu sòng

Đêm ngày đem nước vào đồng

Lúa mình lại đẹp, thì lòng lại vui

Or

The panicles are choking under the evening sun, dear!

Let us use our strength to fight the disaster

You men, use a “gau giai”

We women, will use the “gau song”

Let us water the rice fields day and night

If our rice crops are healthy, our hearts will be happy

Series of bamboo water wheels along the rivers had contributed to the beauty of the landscapes in Quang Nam and Quang Ngai Provinces during the early 1900s. From 1955 to 1975, the construction of canals has reduced because of the war, but farmers started to use water pumps to irrigate rice fields. After 1975, effort to dig/build irrigation canals were strengthened again (UNEP, 2005). The area of irrigated land area in the country increased from 1.4 million hectares in 1978 to about 3 million hectares in 1993 (FAOSTAT). In 2001, about 2.505 million hectares of rice land or 63% of national rice land were irrigated rice land (GSO 2002).

VI. The Application of Fertilizers to Rice Crop

Farmers in the past ranked the contribution of fertilizer in rice production as second position and they expressed this through the following saying:

Nhất nước, nhì phân, tam cần, tứ giống

Or

Water first, fertilizers second, hardworking third, seed/variety fourth

Farmers in the past also said that

Ruộng không phân như thân không của

Or

A rice field without fertilizer is similar to a person having no wealth.

And, similarly, they said

Người đẹp nhờ lúa, lúa tốt nhờ phân

Or

People are beautiful thanks to silk, rice crops are good thanks to fertilizers


De Datta (1981) reported that in producing 1 ton of grains, high yielding varieties withdraw from the growing medium/soils about 16.2 kgN, 2.8 kgP, 17 kgK and other nutritive elements. Before the availability of chemical fertilizers, farmers in northern and north-central region of Vietnam applied domestic manures and green manures such as azolla to rice. The experiences of farmers about the application of azolla to rice is expressed as follows

Mạ Chiêm không có bèo dâu

Khác nào như thể ăn trầu không vôi*

Or

Seedlings of Chiêm rice without azolla application

Are no different than eating betel without lime

*Eating betel is a popular habit of Vietnamese in the past, as it is described in the legend of betel and areca.

During the war, chemical fertilizers were not available so that farmers gave great effort to grow azolla for rice production. A soldier wrote the following poem:

Chiều nay trực chiến vừa về

Gặp em bên ruộng mãi mê ươm bèo

Vội vàng quần xắng, súng đeo

Cùng em chung sức chăm bèo cho xanh

Gió đưa làn nước lăn tăn

Má em ửng đỏ, nhìn anh em cười

Or

Returning home this afternoon after duty

Seeing you growing the azolla at the rice field

Folding my pants and securing my carrying gun

I join you in azolla growing

The wind ripples the surface of the water

Your cheeks flushed, looking at me you smile

Farmers in Mekong River Delta did not apply green manures to rice crop although there were/are different Sesbania plants. With the availability of chemical fertilizers, the use of manures and green manures in rice production in Vietnam reduced substantially. Majority of farmers in the past planted traditional rice varieties and they do not apply chemical fertilizers. Bui Huy Dap (1985) reported that from 1966 to 1971, yield of rice planted in the Red River Delta during monsoon season increased by 0.7 tons/ha and that planted in Winter-Spring season increased by 0.5 tons/ha with the application of manures. The same author also reported that the application of 45 kgN/ha after the application of manures increased the rice yield further by 0.5 tons/ha, but the application of phosphorus and potassium fertilizers did not result in any further yield increment.

The quantity of chemical fertilizer applied in rice production in Vietnam during the period from 1976 to 1992 increased by 11,5% per year (Nguyen Van Luat, 1994). Also, in 1994, Nguyen Tri Khiem and Pingali reported that the quantity of chemical fertilizers applied to rice production was about 70 to 75% of the total imported chemical fertilizers. In 1996, Nguyen Huu Nghia reported that all irrigated rice farmers applied chemical fertilizers to rice, while about only 45% of rainfed lowland rice farmers applied chemical fertilizers to rice.

Majority of farmers applied urea as nitrogen fertilizer and Vu Tuyen Hoang (1990) reported that farmers applied about 80-100 kgN/ha to rice during Winter-Spring season, and about 70-80 kgN/ha to Summer-Autumn and monsoon seasons. In 1996, the quantity of chemical fertilizers used in Vietnam was about 1.5 million tons of chemical fertilizer (FAOSTAT). In the recent past the Site-Specific Nutrient Management (SSNM) was popularized to rice farmers in the Red River Delta in order to improve the efficiency of fertilizer application (Tran Thuc Son et al., 2004). The use of Leaf Color Chart was transfer to farmers in the application of nitrogen fertilizers to rice and the results obtained in Can Tho, Go Cong and Tien Giang showed that the use of Leaf Color Chart reduced the amount of nitrogen fertilizer applied to rice (Pham Sy Tan et al., 2005).

In area affected by acid sulphate soils such as in the Plain of Reeds, Vietnamese farmers dig canals and construct beds to facilitate the flooding and the draining of water to wash the acid sulphate from rice field for rice production (Le Quang Minh et al., 1995). Farmers also applied lime to reduce the acidity of acid sulphate soils, but in soils with pH above 4.5 the application of lime did not have any good effect (Van Bremen, 1980).

In areas with saline affected soils, farmers plow the field during the dry season in order to cut the upward movement of salt from lower soil layers to the top soils. When rain come, farmers raised the field bunds to pond the rainwater for washing the salt in the soils and to prevent saline water from entering the fields and used the salt resistant rice varieties to plant.

VII. The Management/Control of Weeds in Rice Field

Vietnamese farmers recognized that weeds compete with rice and reduce rice yield. Therefore, the management/control of weeds in rice fields has been a major activity of farmers as it was described in the following saying:

Gánh phân, làm cỏ, chẳng bỏ đi đâu

Or

Carry the manures, do weeding, do not run away

With the Chiem crop, farmers usually undertook a second weeding in March, as it is expressed in the following saying:

Bao giờ cho đến tháng hai

Con gái làm cỏ con trai be bờ

Or

When March comes

Girls do weeding, boys repair field bunds

Weed control is important to prevent losses in rice yield and production costs, and to preserve good grain quality. Land preparation is usually started at 3−4 weeks before planting. Plowing destroys weeds and remaining stubble from the previous crop. Weeds should be allowed to grow before doing the harrowing. In addition, land leveling keeps a level field, which helps to retain a constant water level in the field for controlling weeds’ growth.

In the past, farmers used simple tools and manual weeding by hands. Subsequently, mechanical weeding using implements such as push weeders and interrow cultivation weeders for weed control in transplanted rice. Chemical herbicides were imported lately for farmers to control weeds in rice fields. Using herbicides for weed control is particularly important in places where agricultural labor is scarce and wage rates are high. The quantity of imported herbicides increased rapidly after 1991 (Table 2).

Table 2 Quantity of chemical herbicides, insecticides, and fungicides used in Vietnam from 1991 to 2000 (UNEP, 2005)

Total (tons)

Herbicide (%)

Insecticide (%)

Fungicide (%)

1991

20,300

4.1

83.3

9.5

1992

23,100

15.6

75.4

7.0

1993

24,800

15.6

72.7

9.1

1994

20,380

12.5

68.3

15.4

1995

25,666

19.4

64.1

13.5

1996

32,751

22.0

53.0

23.0

1997

30,406

25.0

50.5

23.9

1998

42,738

26.7

47.9

24.3

1999

33,715

26.9

48.3

23.1

2000

33,637

19.7

50.1

27.4

VIII. The Management/Control of Rice Insects

Before the availability of insecticides, Vietnamese farmers used the extracts from the leaves of sầu đông or Azadirachta indica tree and from the trunk of cactus to use as insecticides in crop production in general. Brenier (1917) reported that farmers in Phu Thu and Son Tay used extracts from the peels of grapefruits to control insects in rice production. The following ca dao described the used of the trunk of cactus to use as insecticides in crop production.

Lắm bươm bướm thì đẻ nhiều sâu

Tàn phá hoa màu, làm hại nhà nông

Nàng về ngâm nhựa xương rồng

Gánh ra đem tưới cho bông cho cà

Sâu non cho chí sâu già

Hòng chi sống sót mà ra phá màu

Or

There are many butterflies, they lay a lot of worms

Destroying crops, damaging the farmers

You extract the juice of the cactus

Bring it to the field and apply it to the crops

Old worms, young worms will be killed

So that they could not destroy the crops any more

The insecticides used by rice farmers in Vietnam in the recent past belonged mostly to Methyl Parathion, Methanmindophos, Fuji one, Bassa, Padan. Inappropriate use of insecticides killed also other animals and living organisms in the rice fields such as the toads, the frogs, the spiders, fishes, etc… that provide beneficial service to rice plants and farmers. The in appropriate use of insecticides in rice production also produce harmful effects on the environment and human health as well as leading the insects to develop resistant to the applied insecticides. Therefore, the Integrated Pest Management Program (IPM) was introduced since the 1990s to help farmers in insect control in rice production.

IX. The Management/Control of Diseases

Farmers usually selected varieties that have high resistant capacity to rice diseases to plant. For example, in the 1990-decade, farmers in Thua Thien Province select rice variety CR203 to plant in the Winter-Spring season because this variety is resistant to leaf blast. In the recent past, farmers also applied Cu-contained fungicides and reduced the quantity of N-fertilizer applied to rice crop whenever they find the spreading of leaf blast, neck blast and drying rice leaves and stems.

X. Control of Field Rats

Rats destroyed rice crops, especially during reproductive stages and farmers applied the following techniques to control them:

  • Use non-poisonous snake, strix candida birds, and dogs to catch rats
  • Use arsenic-contained poisons
  • Use rat traps, and
  • Use chili-laded smoke to chase the rat out of their place/house to catch.

REFERENCES

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