Nongkran Maneewan

Land Development Department, Thailand

Thailand occupied 5.5 million rais or 0.88 million hectares of acid sulfate soils.

Distribution of Distribution of acid sulfate soils in Thailandacid sulfate soils in Thailand

Most of area Most of area is in the is in the

Central plainCentral plain

Some in the Some in the South and the South and the

EastEast

1/3KFe3(SO4)2(OH)6

Classification of ASSClassification of ASS1. Severely ASS

pH<4.0 (jarosite 0-50 cm.)

area 870,493 rais (0.139,278 m.ha.)

2. Moderately ASS pH 4.0-4.4

(jarosite 50-100cm.) area

2,211,060 rais(0.353 m.ha.)

3.Slightly ASS

pH 4.5-5.0 (jarosite >100cm.) area 2,428,591

rais(0.388m.ha.)

Problems of ASSProblems of ASSlow pH(<4.0 -5.0 )lack of N P

Al Mn Fe toxicitylow micro organism activities

These soils are suitable These soils are suitable for paddy but give the for paddy but give the

low yield, only 200-300 low yield, only 200-300 kg./rai(1.25-1.875 t/hec )kg./rai(1.25-1.875 t/hec )Therefore,managementsTherefore,managementsof ASS are needed to of ASS are needed to increase rice yields.increase rice yields.

ObjectivesObjectives

• study the appropriate rate of chem. fert.

• study the appropriate rate of liquid organic fert. and effect of GM

• Study the changed of soil properties

• To analyze the economic return

• RCBD, 7 treats. with 3 reps.

• Marl (pH 8.12)pH 8.12) was applied and incorporate in soil 7 days before planting.

H2SO4+CaCO3 CaSO4 + H2O+CO2

rates of marl for basal rates of marl for basal applicationapplication

Ayutthaya 499 kg./rai

1123 kg./rai1123 kg./rai

1000 kg./rai1000 kg./rai

OkharakOkharak

RangsitRangsit

7 Treatments consist of7 Treatments consist of• 0-8-0, 8-8-0 and 12-12-0 N-P2O5-K2O

kg./rai (RS and Ay soil series)

• 0-0-0, 8-0-0 and 12-0-0 N-P2O5-K2O kg./rai (Ok soil series)

• Liquid organic fert. 10 litre/rai• Liquid organic fert. 15 litre/rai• Liquid organic fert. 25 litre/rai

Sesbania rostrata, green manure, was grown and incorporate in soil 10 days before rice planting

chemical fert. was applied 2 times at planting date and 45 days after transplanting and liquid organic fert.was sprayed 3 times at 30 50 and 60 days of rice growth

ResultResult• Factors analysis

GM: GM: N N 2.46 % 2.46 % P2O5 0.417% 0.417%

K2O 2.69 % 2.69 %LOF:LOF: --oxinoxin 1.68 mg/l. 1.68 mg/l.

-giberellin-giberellin 31.01 mg/l. 31.01 mg/l.

Rice production

Rice growth and yields after soils

management

Without liming , rice cannot grow

Rice production on ASS Rice production on ASS Rice yields(kg./rai) from 3 soil series

489.3475481.8537.3532.7482.6468.8

838826860744904900871

1194.2

1112.81091.411090.61157.41199.3

1148.6

0

200

400

600

800

1000

1200

1400

Treatments

yiel

d(k

g./r

ai)

Ok

Rs

Ay

Economic return (bahts/rai)Economic return (bahts/rai)

Economic returns(bahts/rai)

-280-285-241

169

-81-156

103

199921822213

279527662952

2511

2576

226422062290

2196

25722539

-500

0

500

1000

1500

2000

2500

3000

3500

F1 F2 F3 GM LOF10 L+GM LOF 15+GM LOF 25+GM

treatments

net p

rofit

Ok

Rs

Ay

Changed of soil properties(Ay)Changed of soil properties(Ay)

Chem. properties

pH

OM(%)

Before exp.

5.1

4.8

After exp.

5.5

3.4

P2O5 ( mg./kg)

K2O ( mg./kg)

10

>120

36

>120

Changed of soil properties(Ok)Changed of soil properties(Ok)

Chem. properties

pH

OM(%)

Before exp.

4.0

4.6

After exp.

4.7

3.1

P2O5 ( mg./kg)

K2O ( mg./kg)

48

272

29

237

Changed of soil properties(Rs)Changed of soil properties(Rs)

Chem. properties

pH

OM(%)

Before exp.

5.0

1.8

After exp.

5.8

6.2

P2O5 ( mg./kg)

K2O ( mg./kg)

21

177

17

158

Changed of ASS Changed of ASS chemical properties chemical properties

• Acidity decreased(higher in pH)

• OM. decreased

• P2O5 decreased on Ok and Rs

• K2O decreased on Ok and Rs

ConclusionConclusion

1. Liming is necessary to improve ASS, reduced acidity of soils

2.Fertilizer rates2.Fertilizer rates at at 8-8-0 N-P8-8-0 N-P22OO55-K-K22O kg./rai O kg./rai

(50-50-0 N-P(50-50-0 N-P22OO55-K-K22O kg./hec.) O kg./hec.)

gave the highest yields on Rs gave the highest yields on Rs and Ay soil series.and Ay soil series.

3. Green manure with liquid organic fert., increase in growth and yield of rice.

4. Water management, Pre-submergence and drainage, reduce soil acidity because sulfuric acid is leached from the soils and.

5.For economic returns, GM 5.For economic returns, GM with or without LOF gave the with or without LOF gave the highest net incomes on three highest net incomes on three classes of acid sulfate soils.classes of acid sulfate soils.

However, it depends on soil However, it depends on soil fertility. Therefore, soil analysis fertility. Therefore, soil analysis is necessary .is necessary .

commentationcommentation

1.On irrigation areas, ASS can get more benefit than rainfed areas

2.Double crops of paddy/year can be done(2-3 crops/year)

3.wet soils prevent sulfuric acid occurring in the soils because of no oxidation.

4. Liming at the rate of LR only 1 time can be useful for 5

years.