Agricultural Water Savings by SRI for Future Water Management

in Sichuan, China

ZHENG JIAGUOSichuan Academy of Agricultural Sciences

1 General information on SRI application in China

• Brief review of the spread of SRI• Preliminary evaluations of SRI• Improvements in SRI methods for Sichuan• SRI extension in Sichuan

The spread of SRI in China• SRI was developed in Madagascar, being synthesized in the

1980s. • Prof. Yuan Long-ping validated SRI methods with his super-

hybrid varieties in 2001, and hosted an international SRI conference in Sanya, China in 2002.

• The most active institutions for SRI research have been the China National Rice Research Institute (CNRRI) and Sichuan Academy of Agricultural Sciences (SAAS).

• SRI has spread throughout China, with some tech-niques different among provinces and some partial use.

• The concepts and methods of SRI can be used with hybrid rice, Japonica rice, and even with other crops such as wheat.

SRI is a promising methodology to increase rice yield and water productivity

• The average yield from hybrid rice in Sichuan is 8.5 t/ha.• When SRI methods were first introduced, they

could increase rice yield by 20%, • With modification in the method of transplanting

(oblong and triangle method), the increase achieved was still higher, almost 55% (Table 1).

• The spacings used in ‘modified SRI’ are considerably greater than in the original SRI.

3 seedlingsseparated

3 seedlings in 1 hill

Transplanting pattern Yield(t/ha)

Compared to CK

+ t/ha + %

CK 8.65 -- --SRI – standard spacing 10.42 1.77 20.4Triangle version of SRI 13.39 4.74 54.8

3rd leaf 2nd leaf Flag leaf Average

Length Width Length Width Length Width Length Width

SRI 64.25 1.57 71.32 1.87 57.67 2.17 64.41 1.87

CK 56.07 1.43 62.03 1.57 48.67 2.01 55.56 1.67

Table 1. Yield response to different planting patterns in rice

Table 2. Leaf blade size (cm) in response to application of SRI methods

SRI promotes more vigorous growth

• With SRI methods, rice plant phenotypes from any given genotype are improved

• Leaf blades become bigger, especially the functional leaves (Table 2)

• Plant height and culm length become longer

• Leaf area index (LAI) is also much higher compared to CK.

MethodRice stage

Stem SheathGreen

leafWither-ed leaf

Pani-cle

Bio-mass

SRI

Full heading

6,396 6,555 7,169 316 2,362 24,902

Mature 4,109 3,266 3,390 2,667 13,592 25,407

CK

Full heading

3,775 5,595 3,881 254 1,205 14,710

Mature 2,475 3,065 1,661 1,639 7,936 15,833

SRI over CK

+/-%

Full heading

69.4 17.12 84.7 24.07 96.0 59.1

Mature 66.0 6.6 104.1 62.67 71.3 60.5

Comparison of dry-matter accumulation

Lower inputs, especially water-saving

• SRI plants showed fewer insect problems and diseases, and seed requirements were reduced by 50-90%.

• During the rice-growing season, irrigation water was reduced by 25.6%.

• Both WUE and IWUE were higher, by 54.2% and 90.0%, respectively, thereby significantly reducing water consumption.

Limiting factors for adoption

• The number of foundation plants is less with SRI.

• It is hard to transplant the young seedling at 2-leaf age in multiple cropping systems.

• Organic fertilizer materials are in short supply.

• Certain management measures such as timely weeding and keeping the soil moist are considered too complex and laborious.

Improved SRI methods for Sichuan

① Using tray nursery to raise seedlings

• The seedling nursery is managed under upland (unflooded) conditions, with plastic trays.

• Seedlings are removed carefully from the nursery and are transported quickly and placed gently into paddy field within 15-30 minutes.

• This avoids a long recovery time (there is little transplant shock); leaf age can be extended this way to 5.5.

30cm

15cm

Farmers’ usual practice

Leaf-age 7 Oblong >6 seedlings

40cm

35cm

7cm

② Modified SRI: oblong with triangle

7

8

9

10

11

12

13

14

CK SRI S+3 S+T O+T

Transpl anti ng pattern

Yie

ld(T

/ha)

Transplanting pattern and yield results

S+3 = Square with 3 seedlings; S+T= Square with triangle;

O+T = Oblong with triangle

7

8

9

10

11

12

13

14

40× 40 40× 45 45× 45 45× 50 50× 50 55× 55

Space ( cm)

Yield

(t/

ha)

Relation between yield and transplanting density with

triangular transplanting configuration

752.6 737.2 724.5 696.1

576.5

500

550

600

650

700

750

800

850

公斤

/亩

3叶/5000 4叶/6000 5叶/7000 6叶/8000 7叶/13636

叶龄与密度的组合

移栽叶龄与密度组合的稻谷产量（2005，新都）

③ Younger seedlings are better

④ Application of herbicide for weed control – so far, no soil-aerating weeding is being used

⑤ Adding chemical fertilizers when needed

⑥ Mid-season drainage for inhibiting unproductive tillering

⑦ Shallow furrows in field for drainage

• This is appropriate for the alternate wetting and drying (AWD) method, an effective and easy method for SRI water management.

• Shallow furrows help to implement AWD, maintaining aerated soil surfaces while some water remains in the furrows and moves laterally to moisten the root zone.

Shallow furrows in paddy field

SRI extension in Sichuan

• Extension has been guided by the Provincial Agricultural Extension Bureau.

• By 2010, the SRI area in Sichuan had reached >300,000 ha, starting from 1,133 ha in 2004.

• The average SRI yield has been 9.5 t/ha, representing an average increase of 1.8 t/ha over the province average paddy yield.

Year 2004 2005 2006** 2007 2008 2009 2010

SRI area (ha) 1,133 7,267 57,400 117,267 204,467 252,467 301,067

SRI yield (kg/ha) 9,105 9,435 8,805 9,075 9,300 9,495 9,555

Conv. yield (kg/ha) 7,740 7,650 7,005 7,395 7,575 7,710 7,740

SRI increment (t/ha)* 1,365 1,785 1,800 1,680 1,725 1,785 1,815

SRI % increase in yield* 17.64 23.33 25.7 22.72 22.77 23.15 23.45

Grain increment (tons) 1,547 12,971 103,320 197,008 352,705 450,653 546,436

Input increment by SRI(RMB/ha)

834 969 736.5 771 900 1,020 1,200

Grain price (RMB/kg) 1.44 1.44 1.44 1.5 1.8 1.84 1.95

Additional net income attributable to SRI in Sichuan

(million RMB )*1.28 11.64 106.51 205.10 450.85 571.69 704.27

Table 4. Extension of SRI in Sichuan province

2. Water savings for rice

• General information about Sichuan province

• Water-using characteristics in rice cultivation

• Individual research on water-saving for SRI

• Impact of water-saving techniques and

demonstrations in Sichuan

Sichuan is located in southwest China• The rainfall is 1,000 mm annually.• Water resources are about 3,040 m3 per capita, which is

higher than China's average. • The hilly regions have the most serious water shortage.

The water resources per capita here are 940 m3, just 30.9% of the province average, and less than 40% of the national average of 2,477 m3.

• Agriculture consumes 80% of the total water resources in Sichuan.

• Water use efficiency (WUE) of staple crops such as rice, maize, and wheat is about 0.9 kg/m3.

① Irrigation systems well developed on Chengdu Plain

• Chengdu Plain covers 10,000 km2. • Dujiangyan irrigation system, built over 2,000 years

ago, enables irrigation automatically. • The thermal conditions provide adequate temperature

for the rice-wheat cropping system. • But WUE is lower because of flood irrigation or string

irrigation.

② Seasonal droughts are the main restricting factor in hilly areas

• Seasonal droughts are quite frequent, due to the uneven distribution of rainfall during rice growth.

• Drought disasters, such as withered rice seedlings or waiting for rainfall to transplanting, occur every year.

WitheringWithering Yellow leafYellow leaf

Lack of water

Lack of water

DelayDelay Yellow\whitherYellow\whither Low seed setLow seed set

Sow Transp. Elongation Heading Mature

Nursery Tiller Panicle initiation Filling and ripen

SpringSpring Summer Hot summer

The influence on rice from seasonal drought in Sichuan hilly region

Drought

③ Groundwater resources are seldom used directly

• Agriculture relies mostly on surface water. • Rice depends on permanent paddy field water

storage in the hilly region, because there are no reservoirs or irrigation projects.

Experiences on rice water-saving

Landscape and the experiment plots

① Dry seedbed nursery

• The seedbed is established under upland conditions and kept dry during the nursery period.

• Because rainfall can be used directly in upland seedbeds, more than 50% of the irrigation water is saved during the nursery stage (about 45d, ≥7 leaf age). Also, seedling quality is much better than with the wet seedbed nursery.

Rain-fall

(m3/ha) Irrigation water (m3/ha)

Total consumption

(m3/ha)

Comparison to CK (±)

(m3) (%)

DS 315 95.1 410.1 484.1 54.14WS (CK) 315 579.2 894.2 -32.27 -

Emer-gence(%)

Seed-ling(%)

Height(cm)

Dry matter(g/seed-

ling)

Dry wt/fresh(%)

No. of tillers/

seedling

Recov-ery time

(days)

DS 92.6 89.2 29.98 0.63 24.42 4.36 0.5

CK 82.7 79.2 39.49 0.57 17.17 2.94 7.5

Table 5. Water consumption for rice nursery

Table 6. Seedling quality differences between nursery methods

DS: Dry seedbed; WS: Wet seedbed

Dry seedbed nursery

② Mulching in rice cultivation

• In seasonally drought-affected regions, can save 30% of

water, and increase grain yield by 6%; increase WUE by

0.52 kg/m3; and increase IWUE by 1.24 kg/m3.

• Mulching conserves soil moisture and suppresses weeds.

• Small farmers have the labor to manage the mulching.

• Mulching with plastic film saves more water and reduces

losses to drought. But plastic pollution can become a

serious problem.

Mulching with wheat straw

Caution: Plastic pollution

can be a problem

Treatment LP T-SF SF-B B-FH AFH

MBR 1,650.0 651.9 603.75 327.6 273.3

CK 1,650.0 844.8 1,085.1 1,629.3 912.6

MBR: mulching of wheat straw into broad rows; CK: farmers’ practice.

Effective rainfall was 2,585.1 m3·hm-2.

LP: Land preparation; T: transplanting; SF: sun field; B: booting;

FH: full heading; AFH: after full heading.

The same is as in the following tables.

Table 7. Comparison of irrigation water amounts (m3 per ha) in different growth stages during the rice-growing season

Yield(kg·hm-2)

Irriga-tion

(m3·hm-2)

TWC(m3·hm-2)

WUE(kg·m-3

To CK±

(kg·m-3)

IWUE(kg·m-3)

To CK±

(kg·m-3)

MBR 9,467.10 3,506.55 6,091.65 1.55 0.52 2.70 1.24

CK 8,941.65 6,121.80 8,706.90 1.03 - 1.46

Table 8. Comparison of water efficiency under different models

Note: TWC: total water consumption; WUE: water using efficiency; IWUE: irrigation water using efficiency. The same is as in the following tables.

③ Irrigation methods

• AI: aerobic irrigation, as recommended for SRI

• AWD: alternative wetting and drying

• SWD: shallow\wet\dry sequential management

Impact of water-saving techniques

• The technical approach includes:– Tillage, nursery usage, water and fertilizer

management. • Significant quantities of water have been saved. • Traditional water consumption in paddy fields

was 9,795.2 m3/ha, with 8,279.85 m3/ha of this being irrigation water.

• Water productivity was 0.82 kg/m3, and the irrigation water use efficiency was 0.97 kg/m3.

leakage

稻田

Evaporation

Irrigation Drainage

Rainfall

Rainfall

Water requirement for

paddy rice

1,717.8 m32.07mm/d

6,364.4 m3

1.89 mm/d

Spilled

Water saving: 2,193m3/ha (22.04%)

WUE = 1.12 kg/m3

+0.30 kg/m3

IWUE = 1.34 kg/m3

+0.37 kg/m3

Water balance in paddy field and water requirement (modified SRI)

202.5 m3

3. Prospects of water management

• Rice and water management • Future trends in crop cultivation• Key research subjects for water saving in

rice cultivation

Rice and water management • Rice is the world’s most important food crop and a

major staple food. – China’s 31.7 million ha of rice fields, which

account for 20% of the world’s rice area, produce about 35% of total rice grain.

• Rice consumes large quantities of irrigation water, up to about 90% of the total water for all crops.

• However, fresh water for irrigation is becoming scarce because of increasing competition from urban, industrial, and environmental factors.

• Water limitations threaten the sustainability of irrigated rice systems in many countries.

• Rice offers great potential for saving irrigation water because its physiological water requirement (4500 m3 water/ha) is much less than what is currently (incorrectly) considered to be needed and than what is currently applied.

• Water-saving rice-cultivation methods are urgently needed to keep up with future food demands, while at the same time they are important for ensuring the future viability of rice production systems.

Future trends in crop cultivation• To promote sustainable development in agriculture,

China must simplify the cultivation process, reduce the water requirement, and lighten the workload.

• Direct sowing of rice and ratooning will be popular, but some agronomic questions must be answered.

• Agricultural machinery must be introduced into all crops cultivation.

• SRI is not a fixed technology, but rather a set of ideas for creating a more beneficial growing environment for rice. – We expect further modifications and improvements

Key research subjects for water saving in rice cultivation

• Water balance in paddy fields and water requirements in different ecosystems. – The growing of rice should be based on scientific

knowledge and consider following factors: regional ecological conditions, cropping systems, natural rainfall, available irrigation resources, and so on.

• Varieties for drought tolerance and screening methods.

– There is considerable difference among varieties for their drought tolerance. Some can be suitable in arid areas or areas with more uncertain water availability.

• Sensitive growth stages for water stress and their influence.– Limited water resources to be allocated for use

during rice’s most sensitive growth stages. Natural rainfall needs to be used as efficiently as possible, and the water demands for rice growing should be reduced as much as possible.

• Engineering approach for saving water. – Increased water conservation projects in hilly regions

should be pursued, along with reductions in water losses in irrigation channel systems; appropriate use of groundwater warrants systematic development.

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