Authors: Giriraj gupta1 ,Sushila Vishnoi2 and Subhita Kumari3
1Dept of Agronomy, RCA, MPUAT, Udaipur
2Dept of Ag. Eco. and Management, RCA, MPUAT, Udaipur
3Dept of Soil science and Ag. Chemistry, RCA, MPUAT, Udaipur
Rice (Oryza sativa L.) is the world's most staple food for about 2.5 billion people and more than 50 per cent of the world's population depends on rice as the major source of calories. India is the leading rice producing country in terms of area and it is the second largest producer next to China. Rice is grown in an area of 43.97 million ha annually with a production of 104.32 million tonnes in 2011-12, which contributes 45% of the total food grain production of the country. The leading states in rice cultivation are: West Bengal, Uttar Pradesh, Andhra Pradesh, Punjab and Haryana (Anon., 2013).
Brief History of SRI
The System of Rice Intensification (SRI) developed in Madagascar by father Henri de Laulanie (1983). In A.P., SRI is experimented in all the 22 districts during 2003 kharif with encouraging results. In India, it occupies an area about 5.25 m ha area under SRI (NABARD, 2013).
SRI is a package of practices especially developed to improve the productivity of rice grown in paddy area. Unlike the conventional method of continuous flooding of paddy fields, SRI involves intermittent wetting and drying of paddies as well as specific soil and agronomic management practices.
Key principles of SRI
• SRI methodology is based on four main principles that interact with each other:
• Early, quick and healthy plant establishment
• Reduced plant density
• Improved soil conditions through enrichment with organic matter
• Reduced and controlled water application
Concept of SRI
Rice plants perform better because
• Younger seedling (more tillering capacity)
• Careful transplanting (avoid trauma, less root injury)
• Wider spacing (less competition)
• Less water (aerated soil, more microbial activity)
• Incorporation of weeds (enhance organic matter)
• High root volume
Table 1. Differences between conventional rice cultivation and using the System of rice Intensification
|Content||Conventional method||SRI method|
|Seed||50-60 kg ha-1||5-6 kg ha-1|
|Transplanting||Seedlings about 25-30 days old||Seedlings about 8-12 days old|
|No. of hills/m2||About 50 hills (clumps) are planted m-2||16 hills are planted m-2|
|No. of seedlings/hill||Usually 2-3 or more seedlings are planted||Only one seedling|
|Fertilizers supplements and pesticides||Application of chemical fertilizers, pesticides, herbicides and insecticides||Preferences given to organic manures, only supplementary fertilizers are applied|
|Water management||Continuous flooding||Only moist conditions|
|Weed management||Weeds manually removed from the field||Weeds turn down into the field by a conoweeder|
Comparison of expenditure and returns in SRI and conventional paddy production
Andhra Pradesh - Adusumilli and Bhagyalaxmi (2011)
This graph show that SRI system gives higher return in terms of grain value, straw value, gross return and net return.
This graph show that SRI system gives higher productivity in terms of HL(housr), manure, nitrogen, phosphorus, seed rate and irrigation.
Cultivation of rice by system of rice intensification (SRI)
1. Selection of suitable soil
Farmers who want to cultivate paddy by SRI method:
- Should level their plots
- Should plan for drainage channels, if needed
- Should make plots of small size
What are suitable soils?
• Soils that are not affected by salinity
• Level fields those are convenient to irrigate and drain
• Fertile soils
2. Selection of suitable varieties
• Hybrids and varieties with heavy tillering (80 to 100 for individual plants)
• Deeper and more effective roots
• Higher fertilizer responsive varieties
• Some suitable varieties for SRI
Varieties: KRH 2, Arize 6444, Pusa Basmati 5, CAU R-I, Deku, Pusa Basmati 1121, Dubraj Rice, IR-20, IR-50, and Navara rice, Gujarat- GR-11, Jaya, Gurjari, GR-4, GR-7, Krishna Kamod, GR-101, Masuri
3. Seed selection and treatment for SRI
In case of farmers using their own seeds:
• 1kg of salt is dissolved in 10 liter of water.
• The seeds are soaked in this solution.
• The good seeds will settle down and chaffy/ light weight/ infested seeds will gloat.
• The floating material will be removed and the good seeds will be rinsed in fresh water.
• The seeds are treated with pseudomonas, azospirillum and phosphobacteria of 50g each.
• The treated seeds are soaked in water for 12 hours and then kept in a closed gunny (jute) bag in wet condition for another 24 hours in a shady place. This facilitates the sprouting of the seed after sowing.
SRI by nursery method
Preparation of soil mixture
• 4 m3 of soil is needed for each 100 m2 of nursery
• Mix 70% soil + 20% well decomposed FYM + 10% rice hull
• Incorporate in the soil mixture 1.5 kg of di-ammonium phosphate
Nursery bed is prepared in this manner
1st layer : 1 inch thick well decomposed FYM
2nd layer : 1.5 inch soil
3rd layer : 1 inch thick well decomposed FYM
4th layer : 2.5 inch soil
All these layers should be thoroughly mixed
Raising of nursery
Preparation of nursery area
• Prepare 100 m2 nurseries for 1 ha area
• Select a leveled area near the water source
• Spread a plastic sheet on the shallow raised bed to prevent roots growing deep into soil
Filling in soil mixture
• Place a wooden frame of 0.5 m long, 1 m wide and 4 cm deep divided into 4 equal segments on the plastic sheet or banana leaves
• Fill the frame almost to the top with the soil mixture
• Sown the pre-germinated seeds weighing 90- 100 g/m2 uniformly and cover them with dry soil to a thickness of 5mm.
• Sprinkle water immediately using by rosecan to soak the bed and remove the wooden frame and continue the process until the required area is completed.
• Watering the nursery by rosecan as and when needed (twice or thrice a day) to keep the soil moist.
• Protect the nursery from heavy rains for the first 5 DAS.
• At 6 DAS, maintain thin film of water all around the seedling mats.
• Drain the water 2 days before removing the seedling mats for transplanting.
• Preparation of the main field in SRI is the same as in lowland rice
• Field should be evenly leveled and there should not be standing water in the field during transplantation
• Draw lines both way (25x25 cm) with marker
• The age of the seedling should be 8-12 days
• The seedling will have 2-3 leaves
• The seedling should be healthy and strong
• Carefully lift the seedling with seed, soil and roots
• Place the seedling without plunging too deep into the soil
• Single seedling planted per hill
Precaution required in transplanting:-
• Transplant the third leaf appears, at 8-12 days old.
• Before transplanting, disassemble the seedbed and remove the seedlings.
• Be careful not to damage the young roots.
• Put the seedlings on a plate or tray to make it easier to transport them to the field.
• With wider spacing and a single plant per hill.
• Transplant seedlings at shallow depth, just 1-2cm deep.
• Transplant within 30 minutes of pulling out of seedlings.
Table 2. Yield parameters and yield as influenced by age of seedlings
|Seedling Age||Grain yield (kg ha-1)||Straw yield (kg ha-1)||Panicles per hill||Grains per panicle||1000 grain weight (g)|
Raichur (Karnataka) Manjunatha et al. (2010)
Table 3. Grain yield, straw yield and economics of rice as influenced by spacing under SRI
|Spacing||Grain yield (t/ha)||Straw yield (t/ha)||Grass income ( Rs/ha )||Net income (Rs/ha )||Benefit cost ratio|
|25 x 25 cm||3.86||5.95||3070||1570||1.02|
|30 x 30 cm||3.12||5.01||24.9||9.8||0.65|
|CD (P = 0.05)||0.02||0.35||-||-||-|
Soil type: sandy clay loom soil Dahal and Khadka (2012)
Dahal and Khadka (2012) studied that the crop planted in the geometry of 25x25 cm produced significantly higher effective tiller per m2, higher 1000 grain weight, grain yield, net return and B:C ratio than other planted geometry viz., 15x15 cm, 20x20 cm and 30x30 cm.
• Wide spacing is important in SRI method. The row to row distance and within a row plant to plant distance should be 10 x 10 inches (25 x 25 cm).
• With this spacing there would be 16 plants per square meter in SRI method. If there is any doubt regarding the survival of plant then two plants can be transplanted per hill.
• In the conventional method 40-50 hills are transplanted per square meter with 4-5 plants per hill.
Multiple advantages of using weeder
• No need to use herbicides (save cost)
• Weed incorporation into soil (returns plant nutrients to the soil)
• Less labour needed for weeding
• Incorporation of top-dressed fertilizer
• Disturbance of the soil's surface aerates the top horizon
• Promotion of root and crop growth
• During transplanting the field should be just wet - not flooded.
• The next irrigation with 1-2 cm of water is taken up one or two days after transplanting (depending on the soil type, season, etc.)
• Only when this water is completely absorbed, the next irrigation is applied: again 1-2 cm water.
• This procedure of "wetting and drying" is continued throughout the vegetative stage.
• Standing water of 2 cm is maintained from panicle initiation till 15-20 days before the harvest.
• Integrated nutrient management system is recommended. However, the use of organic manure is emphasized as they are found to give better response.
• The soils are improved through organic matter additions, many nutrients become available to the plant from the organic matter. Depending on the yield level and on the farming system, some farmers use exclusive organic fertilization for their SRI plots.
The grain matures even while the crop is green in colour. Hence farmers should be ready to undertake timely harvesting. The crop mature in 100-115 days in SRI method where as in traditional method it matures in 110-130 days. In SRI method the crop mature 10-15 days prior to traditional method.
Advantages of SRI
• Saving on seed cost as the seed requirement is less.
• Saving on water as irrigated - dry method is followed.
• Cost of external inputs gets reduced as chemical fertilizers and pesticides are less used.
• Less land is needed for nursery preparation.
Disadvantages of SRI
• SRI requires well-drained soils
• SRI requires special skills for transplanting
• Small single seedlings could not be used due to the high temperatures, sun radiation, or very high evapo-transpiration rates at transplanting time
• Requires skilled labor for management practices
• Drastic change of farmer practices
This study suggested that agronomic manipulation like planting of young seedling (8-12 days old) singly planted at 25 x 25 cm and conoweeding had tremendously contributed for the enhancement of growth, nutrient uptake and yield of rice.
• From the present study it can be concluded that, SRI method of cultivation recorded significantly higher growth parameters, yield attributes, grain and straw yield as compared to conventional method of cultivation at all the growth stages.
• There is a dual advantage in the SRI method, viz. reduction in cost of cultivation and increase in yields (50 to 80 %).
• It is now clear from the results that standing water is not essential for rice cultivation and then it has the capacity to withstand water stagnation.
• By traditional method of rice culture, 2500 to 5000 liters of water are needed to produce 1 kg rice grain. By adopting SRI water can be reduced to a great extent (25-50%).
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About Author / Additional Info:
I am currently pursuing Ph.D