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Go to start Pig Feed Improvement through Enhanced Use of Sweet Potato Roots and Vines in Northern and Central Vietnam
Contents:
INTRODUCTION
PART I -SELECTING AND GROWING SWEET POTATO FOR LIVESTOCK
1 Technology for growing dual-purpose and forage-purpose sweetpotato in the Northern Midlands of Vietnam
2 Technology for growing dual-purpose and forage-purpose sweetpotato in the Red River Delta of Vietnam
3 Technology for growing dual-purpose and forage-purpose sweetpotato in North-Central Vietnam
PART II - SWEETPOTATO ROOT AND VINE PROCESSING AND FEEDING TO PIGS
1 Sweetpotato vine and root ensiling methods and use of silage as pig feed
2 Feed crops and their processing and storage methods
3 Composition of concentrate feed mixtures (basal feed) and the rations for pigs for various weight categories
Technical supplement: Some principles of pig nutrition in the tropics

3. Technology for growing dual-purpose and forage-purpose sweetpotato in North-Central Vietnam

3.1 Characteristics of North-Central Vietnam

3.1.1 Soils

North-Central Vietnam was deposited by the Ma River and the Huong River, resulting in infertile coastal-sandy soils with some alluvial characteristics.

3.1.2 Climatic conditions

North-Central Vietnam is commonly hit by storms from the east sea and by hot wind currents from the west part of the Truong Son mountains. It is, therefore, often plagued by floods and drought. During the heavy rainy season, the whole rainfall comes down from the east side of the Truong Son mountains and creates floods immediately. The two distinct seasons are the rainy season from May to October when the average temperature hovers around 25-35 °C, and the dry season from November to April. The average rainfall is 264.7 mm/month, mainly concentrated in three months during the rainy season (September to November), with common flooding between June and October every year.

3.13 Population and density

Population of North-Central Vietnam is 10,007,200, of which 87.7 % reside in rural areas. Average agricultural land per capita is higher than that of the Red River Delta, averaging 910.3 m2, of which rice cultivation area occupies 75%.

3.14 Crops and production systems

In North-Central Vietnam main rotation formulas between sweetpotato and other crops are as below:

- Only subsidiary crops:

Winter/Spring sweetpotato - Rice - Bean
Soybean - Sesame or autumn ground nut - Winter/Spring sweetpotato

- One rice crop with two subsidiary crops:

Winter/Spring sweetpotato - Main winter rice
Spring sweetpotato - Early winter rice - Potato
Spring sweetpotato - Early winter rice - Winter sweetpotato
Spring groundnut - Early winter rice - Winter sweetpotato

- Two rice crops with a winter crop:

Late spring rice - Early winter rice - Winter sweetpotato

3.2 Geographical location

North-Central Vietnam consists of the following provinces: Thanh Hoa, Nghe An, Ha Tinh, Quang Tri, Quang Binh, Thua Thien Hue. The following recommendations also apply to some neighbouring provinces that share similar topographical, soil, and cropping characteristics.

3.3 Recommended sweetpotato varieties suitable for root and vine dual-purpose and their characteristics

3.3.1 The characteristics of yield, agronomic performance, and growing period

Distinguishing characteristics

Varieties

 

K51

K4

KL5

Cuc nhanh

Chiem dau

Root yield (ton/ha)

20-30

15-20

13-20

12-15

8-12

Vine yield (ton/ha)

15-20

17-22

15-25

15-20

10-15

Root DM yield (ton/ha)

3.15-4.25

5.6-7.3

3.8-6.5

4.8-6.4

3.3-5.0

Root starch yield (ton/ha)

1.2-2.3

3.5-5.0

3.0-5.5

3.5-4.0

2.0-3.0

Season suited to planting

Winter, spring

Winter, summer

Winter, spring

Winter, spring

Winter, spring

Tolerance performance:

 

 

 

 

 

Drought tolerance

Good

Good

Medium

Medium

Fair

Submergence tolerance

Fair

Fair

Fair

Medium

Medium

Cold tolerance

Good

Good

Fair

Fair

Fair

Leaf insect tolerance

Good

Good

Medium

Fair

Medium

Weevil tolerance

Good

Fair

Medium

Medium

Fair

Growing time (days)

80-90

90-120

90-120

120-180

120-180


3.3.2 The characteristics of utilization, vine, root and storage

Distinguishing characteristics

Varieties

 

K51

K4

KL5

Cuc nhanh

Chiem dau

Root palatability

 

 

 

 

 

  • For humans (boiled)

Low DM

High DM

High DM

High DM

High DM

  • For pigs (cooked)

Good

Acceptable

Fairly good

Fairly good

Good

Vine palatability

 

 

 

 

 

  • For humans (boiled)

Sweet

Bitter

Sweet

Acceptable

Bitter

  • For pigs
    (fresh)

Sweet

Bitter
(Should be cooked)

Sweet

Acceptable

Bitter
(Should be cooked)

Method of root storage

 

 

 

 

 

  • Time (months)

3-4

2-3

3-4

4-5

2-3

  • Way to store

Fresh, dried

Fresh, dried

Fresh, dried

Fresh, dried

Dried

Root morphobgy

 

 

 

 

 

  • Color of skin

Light yellow

Yellowish

Red

Red

Yellow

  • Color of root flesh

Red

White,yellow

White,yellow

White,yellow

White-yellow

  • Shape of root

Elliptical

Roundish

Slender

Slender

Elliptical

Vine morphology

 

 

 

 

 

  • Shape of leaf

Round heart

Long heart

Dentate

Serrated

Round heart

  • Color of tender leaf

Green

Violet

Green

Green

Light green

  • Color of adult leaf

Dark green

Light green

Green

Dark green

Light green

  • Color of stem

Green

Purple green

Green

Green

Purple green

 

3.4 Sweetpotato varieties suitable for forage purpose and their characteristics

3.4.1 The characteristics of yield, agronomic performance, and growing period

Distinguishing characteristics

Varieties

 

K51

KL1

KL5

H.1.2

Cuc nhanh

Fresh vine yield (ton/ha)

6-8.7

6.3-11.34

7.2-12

8.4-13

6.8-10.2

Vine DM yield (ton/ha)

1.93

2.20

2.69

2.78

2.30

Leaf protein yield (ton/ha)

0.39

0.40

0.51

0.56

0.41

Season suited to planting

Winter, spring

Winter, spring

Winter, spring

Winter, spring

Winter, spring

Tolerance performance:

 

 

 

 

 

Drought tolerance

Good

Good

Medium

Medium

Fair

Submergence tolerance

Fair

Fair

Fair

Medium

Medium

Cold tolerance

Good

Good

Fair

Fair

Fair

Leaf insect tolerance

Good

Good

Medium

Fair

Medium

Weevil tolerance

Good

Fair

Medium

Medium

Fair

Branching re-growing

Strong

Strong

Strong

Strong

Strong

3.4.2 The characteristics of utilization, vine, root and storage

Distinguishing characteristics

Varieties

 

K51

KL1

KL5

H.1.2

Cuc nhanh

Vine palatability

 

 

 

 

 

  • For humans (boiled to eat)

Sweet

Sweet

Sweet

Sweet

Sweet

  • For pigs (fresh)

Sweet

Sweet

Sweet

Sweet

Sweet

Method of vine storage

 

 

 

 

 

  • Time (months)

34

2-3

34

4-5

4-5

  • Way to store

Dried

Dried

Dried

Dried

Dried

Vine morphology

 

 

 

 

 

  • Shape of leaf

Long heart

Round heart

Dentate

Round heart

Serrated heart

  • Color of tender leaf

Light green

Light green

Green

Green

Light green

  • Color of adult leaf

Dark green

Light green

Green

Dark green

Green

 

3.5 Technologies that can be applied to increase vine and root yield

3.5.1 Selecting the appropriate variety

Using purpose

Spring crop

Winter crop

Dual purpose

K51.K4.KL5

K51.K4.KL5

Forage purpose

K51,KL5,KL1

K51,H.1.2,KL5

3.5.2 Planting season

 

Spring crop

Winter crop

Planting season

15 February- 30 March

15 September-30 October

Favorable conditions


Unfavorable conditions

  • Due to low moisture require­ ment, sweetpotato can grow where groundnut and sesame cannot.
  • There usually are early rains. It has negative impact on root growth.
  • Sweetpotato is planted between crops to increase land use efficiency.
  • The cold in the beginning and drought at the end of season both have adverse effects on root growth.

3.5.3 Soil characteristics

 

Spring crop

Winter crop

Proper soil type

Mixed sandy, light loamy, river side, along canals and dikes, sandy soils on seaside.

Mixed sandy, light loamy, river side, along canals and dikes, sandy soils on seaside.

Land type

Highland, upland, well drained

Highland, upland, middle land.

 

3.5.4 Soil preparation

 

Spring crop

Winter crop

Requirements

Dry, airy, deeply ploughed.

Deeply ploughed for moisture retention.

Size of beds

1.2 - 1.5m wide, 0.35-0.5m high

1 - 1.5m wide, 0.3 - 0.45m high

Distance between beds

30-35 cm

25-30 cm

Direction of beds

West- East

West - East

3.5.5 Planting method

 

Spring crop

Winter crop

Vegetative multiplication

  • The stems from winter crop or garden crop can be multiplied.
  • Choose the stems that are not infested with viruses or insects. No nitrogen fertilization before cutting
  • Multiplication season is the end of June and beginning of July
  • Plant in mounded beds or flat beds. Irrigate, cut tops early to promote multiple branches.

Multiplication method of planting material from root

  • Choose the small or medium roots with no scratches, no virus, or insect infestation
  • Prepare the soil well, the soil clods must be as fine as for vegetables. The top of the bed is flat, with 1 .2 m width, 20 cm height, fertilize 10 tons of manure/ha before planting as basic fertilizer.
  • Planting density: 40 x 40 cm/hole, the big root should be cut into parts then dipped into ash, planting depth is about 3 cm, cover the surface of the bed with chopped rice straw, water them to keep the plants and soil moist.
  • After the shoots have grown out of the soil surface about 5cm, cut off weak shoots, leave only 2-3 shoots in a hole. When the shoots are 20-25 cm long, cut the top to allow branching, 50 - 60 days later cut the stem to plant.

Preparation before cutting planting material

7-10 days before cutting, apply additional P and K fertilizer (1 -2 kg K/sao), do not water or apply nitrogen

Standards of good planting material

Adult stem, thick and hard, with no root, no virus and insect infestation

Method of cutting planting material

Cut the Island the 2nd section, avoid damaging the stems and leaves. In late afternoon when it is less sunny. Do not dip the stems in water just after cutting

Length of stem (cm) Node number/stem

25-30
6-8

20-25
5-7

Planting method

Put the stem horizontally in the direction of the bed, exposing the top 3-5 cm, cover it with soil from both sides and pat down the soil next to the stem. Lay the stem down flat and no need to leave space between plantlets. Keep the stem fresh. Better plant in the evening. In winter, avoid planting during the northeast windy days.

Direction of beds

North east-South west

North east-South west

Density (stem/m of bed)

5 stem/m

4-5 stem/m

 


3.5.6 Fertilizer

 

Spring crop

Winter crop

Ratio and amount of fertilizers (kg/sao)

300-400 kg manure
2-4 kg urea (N)
12-14 kg phosphate (P)
2-4 kg potassium chloride (K)

300-400 kg manure
3-5 kg urea (N)
12 -14 kg phosphate (P)
2-4 kg potassium chloride (K)

Basic fertilization

Mix manure with P, put in the furrow and cover with soil from the bed. Apply additional 1-1.5 kg urea and 1-1.5 kg potassium chloride, cover with soil. Avoid stems touching fertilizer.

Mix manure with P, put in the furrow and cover with soil from the bed. Apply additional 1-1.5 kg urea and 1-1.5 kg potassium chloride, cover with soil. Avoid stems touching fertilizer.

First additional fertilization

  • Timing
  • Amount (kg/sao)

 

  • At 15-25 days after planting
  • 1-1.5 kg urea mixed with 1-1.5 kg potassium chloride

 

  • At 10-20 days after planting
  • 1-1.5 kg urea mixed with 1-1.5 kg potassium chloride

First additional fertilization

  • Timing
  • Amount (kg/sao)

 

  • At 30-35 days after planting
  • 1-1 .5 kg urea 1-1.5 kg potassium chloride

 

  • 25-30 days after planting
  • 1-1.5 urea 1-1.5 potassium chloride


3.5.7 Cultivation technology

 

Spring crop

Winter crop

Pinching off young shoots

At 25-30 days after planting (several days before or after the 1 st additional fertilization) cut the tops to help branching and optimize vegetative development.

At 25 days after planting (several days before or after the 1 st additional fertilization) cut the tops to help branching and optimize vegetative development.

Re-mount the bed for weed control

At 25-30 days after planting, hoe deeply into soil, turn up the bed slightly linking this activity with the 1 st additional fertilization.

At 10-15 days after the 1 st additional fertilization, hoe, turn up soil slightly. Keep soil moist for 2-3 days after planting so that the stems can re-grow.

At 25 days after planting, hoe soil deeply, turn and earth up the bed slightly, in combination with the 1 st additional fertilization.

At 10 - 15 days after the 1 st additional fertilization, hoe, turn slightly and earth up the bed highly. Keep soils moist for 2-3 days after planting so that the stems can re-grow.

Irrigation

Irrigate 2-3 days after turning up the bed and additional fertilization application.

Irrigate, flood 1/2-1/3 of the furrows, keep soil moist when weather is dry.

Vine lifting

At 45-50 days after planting if too much vine during the first period, some stems should be cut and stems should be lifted to break excessive roots.

At 45-50 days after planting if too much vine during the first period, some stems should be cut and stems should be lifted to break excessive roots.

 


3.5.8 The vine-cutting method for forage varieties

 

Spring crop

Winter crop

First vine harvest

Time to start harvest

 

At 30-40 days after planting when the bed is covered by vine

 

At 35-45 days after planting when the bed is covered by vine

Harvesting criteria

Leave a section of 10-15 cm on the bottom.

Leave a section of 10-15 cm on the bottom.

Subsequent vine harvests

Nitrogen should be added after each harvest (0.5 - 1.0 kg/sao urea).

Cut stems every 10-15 days until the last harvest.

Depending on vegetative growth, cut 2-3 longest stems, up to 4 stems if much growth, leaving 15- 20cm. More stems can be cut near the end harvest

Nitrogen should be added after each harvest (0.5 -1.0 kg/sao urea).

Cut stems every 10-15 days until the last harvest.

Cut 2-3 longest stems of a plant, leaving 15-20 cm. Irrigate while applying additional fertilizer after cutting.


3.5.9 Main insects and protection

 

Spring or winter crop

Weevil

Use traps (For example: chopped sweetpotato pieces) to lure adult weevils to come to lay eggs, then get the traps to kill larvae.

Mound high beds and keep soil moist to reduce weevil damage.

Use biological control such as introduction of natural enemies, manipulation of habitat, conservation of natural enemies through avoidance of pesticide use or trap weevils to eliminate them.

Sweetpotato Hornworm (Agriusconvolvuli)

Sweetpotato rotating with paddy rice helps eliminate insects. Leaf-eating caterpillar can be caught by hand

Scrap

Planting tolerant varieties is the best protection from scrap. Check and elimi­nate the attacked plants.

Black rot

Restrict irrigation during the final period. Rotate sweetpotato with other crops in paddy fields, or plant on highlands.

3.5.10 Harvest

 

Spring crop

Winter crop

Root harvesting
Time to harvest
Date of harvest
Method of harvest


105-120 days after planting
End of May-Start of June
-Avoid damaging roots
- Process, store vine, make dried chips


80-90 days after planting
End of January-Start of February
- Avoid damaging roots
- Process, store vine, make dried chips

Vine harvesting
Time to harvest


Vines can be harvested 45-50 days after planting.


Vines can be harvested 45-50 days af­ter planting.

Subsequent harvests

Every 10-15 days after the first vine harvest.

Every 10-15 days after the first vine har­vest.


3.5.11 Storage

 

Spring crop

Winter crop

Method of root storage

Clean soil or sand from roots, keep in dry, airy, and cool places

Clean soil or sand from roots, keep in dry, airy, and cool places

Some remarks during storage

Check regularly to eliminate rotting roots

Check regularly to eliminate rotting roots

Storage duration

3-4 months

3-4 months

Method of vine torage

Drying or ensiling

Drying or ensiling

Storage duration

3-4 months

3-4 months

Some remarks during storage

After 14 days ensiled feed can be fed to pigs. It can be stored for at least 4-5 months. It has the typical smell and taste of ensiled feed. Check the bags regularly to make sure of anaerobic condition to avoid rot and mould

After 14 days ensiled feed can be fed to pigs. It can be stored for at least 4-5 months. It has the typical smell and taste of ensiled feed. Check the bags regularly to make sure of anaerobic condition to avoid rot and mould


3.5.12 Recommended utilization

 

Spring crop

Vine

The soft and sweet vine can be used as vegetable for humans or forage for animals

Root

Roots can be boiled or dried for human consumption or animal feed

 


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