1185 - Agricultural Water Savings by SRI for Future Water Management
1. Agricultural Water Savings by SRI for
Future Water Management
in Sichuan, China
ZHENG JIAGUO
Sichuan Academy of Agricultural Sciences
2. 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
3. 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
4.
5. 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.
7. Table 1. Yield response to different planting
patterns in rice
Compared to CK
Yield
Transplanting pattern
(t/ha) + t/ha +%
CK 8.65 -- --
SRI – standard spacing 10.42 1.77 20.4
Triangle version of SRI 13.39 4.74 54.8
Table 2. Leaf blade size (cm) in response to application
of SRI methods
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
8. 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.
9. Comparison of dry-matter accumulation
Rice Green Wither- Pani- Bio-
Method Stem Sheath
ed leaf
stage leaf cle mass
Full
6,396 6,555 7,169 316 2,362 24,902
heading
SRI
Mature 4,109 3,266 3,390 2,667 13,592 25,407
Full
3,775 5,595 3,881 254 1,205 14,710
heading
CK
Mature 2,475 3,065 1,661 1,639 7,936 15,833
Full
SRI over 69.4 17.12 84.7 24.07 96.0 59.1
heading
CK
+/-% Mature 66.0 6.6 104.1 62.67 71.3 60.5
10. 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.
11. 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.
13. 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.
17. Transplanting pattern and yield results
14
13
12
Yield(T/ha)
11
10
9
8
7
CK SRI S+3 S+T O+T
Tr anspl ant i ng pat t er n
S+3 = Square with 3 seedlings; S+T= Square with triangle;
O+T = Oblong with triangle
18. Relation between yield and transplanting density with
triangular transplanting configuration
14
13
12
Yield (t/ha)
11
10
9
8
7
40× 40 40× 45 45× 45 45× 50 50× 50 55× 55
Space ( cm)
22. 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.
25. 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.
26. Table 4. Extension of SRI in Sichuan province
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
834 969 736.5 771 900 1,020 1,200
(RMB/ha)
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 1.28 11.64 106.51 205.10 450.85 571.69 704.27
(million RMB )*
27. 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
28. 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 m 3, 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.
29. 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.
30. 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.
Withering Yellow leaf
31. Drought
Spring Summer Hot summer
Sow Transp. Elongation Heading Mature
Nursery Tiller Panicle initiation Filling and ripen
Lack of Delay Yellowwhither Low seed set
water
The influence on rice from seasonal
drought in Sichuan hilly region
32. 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.
34. 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.
35. Table 5. Water consumption for rice nursery
Rain- Total Comparison to CK
fall consumption (±)
(m3/ha) (m3/ha)
Irrigation
water
(m3/ha)
(m3) (%)
DS 315 95.1 410.1 484.1 54.14
WS (CK) 315 579.2 894.2 -32.27 -
Table 6. Seedling quality differences between nursery methods
Dry Recov-
Emer- Seed- Dry wt/ No. of
Height matter ery
gence ling fresh tillers/
(cm) (g/seed- time
(%) (%) (%) seedling
ling) (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
DS: Dry seedbed; WS: Wet seedbed
37. 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.
40. Table 7. Comparison of irrigation water amounts (m3 per ha)
in different growth stages during the rice-growing season
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.
41. Table 8. Comparison of water efficiency
under different models
Irriga-
Yield TWC WUE To CK IWUE To CK
tion
(kg·hm-2) (m3·hm-2) (kg·m-3 ± (kg·m-3) ±
(m3·hm-2)
(kg·m-3) (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
Note: TWC: total water consumption;
WUE: water using efficiency;
IWUE: irrigation water using efficiency.
The same is as in the following tables.
42. ③ Irrigation methods
• AI: aerobic irrigation, as recommended for SRI
• AWD: alternative wetting and drying
• SWD: shallowwetdry sequential management
43. 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.
44. Water balance in paddy field and water
requirement (modified SRI)
2.07mm/d 1,717.8 m3
Evaporation Rainfall
Rainfall
Spilled 202.5 m3
Water
稻田
Irrigation requirement for Drainage
paddy rice
6,364.4 m3 Water saving:
2,193m3/ha (22.04%)
leakage
WUE = 1.12 kg/m3
1.89 mm/d +
0.30 kg/m3
IWUE = 1.34 kg/m3
+
0.37 kg/m3
45. 3. Prospects of water management
• Rice and water management
• Future trends in crop cultivation
• Key research subjects for water saving in
rice cultivation
46. 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.
47. • 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.
48. 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
49. 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.
50. • 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.