System of Rice Intensification (SRI)

What is SRI?

The System of Rice Intensification involves cultivating rice with as much organic manure as possible, starting with young seedlings planted singly at wider spacing in a square pattern; and with intermittent irrigation that keeps the soil moist but not inundated, and frequent inter cultivation with weeder that actively aerates the soil.

SRI is not a standardised, fixed technological method. It is rather a set of ideas, a methodology for comprehensively managing and conserving resources by changing the way that land, seeds, water, nutrients, and human labour are used to increase productivity from a small but well-tended number of seeds. As Father de Laulanié observed, SRI is an amalgamation of multiple beneficial practices.

Paddy Cultivation: Some Myths

Everybody believes that rice is an aquatic plant and grows best in standing water. Rice is not an aquatic plant; it can survive in water but does not thrive under reduced oxygen (hypoxic) levels. Rice plants spend lot of its energy to develop air pockets (aerenchyma tissue) in its roots under continuous inundation. Nearly 70% of rice root tips get degenerated by flowering period.

SRI: Debunking myths

Under SRI paddy fields are not flooded but kept moist during vegetative phase. Later only one inch water is maintained. SRI requires only about half as much water as normally applied in irrigated rice.Over 1,00,000 farmers are experimenting with this system worldwide at present.

SRI Paddy Cultivation requires less water, involves less expenditure and gives more yields. Thus it is beneficial for small and marginal farmers.SRI was first developed in Madagascar during 1980's. Its potential is under testing in China, Indonesia, Cambodia, Thailand, Bangladesh, Sri Lanka and India. In Andhra Pradesh. SRI was experimented in all the 22 districts during 2003 Kharif with encouraging results.

SRI Technology Uses Less External Inputs

In SRI paddy cultivation, less quantity of seeds - 2 kg / acre is required. Hence fewer plants per unit area (25 x 25 cm) whereas in mainstream chemical intensive paddy cultivation requires 20 kg seed per acre. (1 acre= apprx 0.4 ha).

A comparison of SRI and conventional method of rice cultivation is as follows

SRI is initially labour intensive

• Needs 50% more man-days for transplanting and weeding.
• Mobilises labour to work for profit.
• It offers an alternative to the resource poor, who put in their family labour.
• Once the right skills are learnt and implemented, the labour costs will be lesser.

SRI encourages rice plant to grow healthy with

• Large root volume
• Profuse and strong tillers - Maximum tillering (30 tillers/plant can be easily achieved; 50 tillers per plant are quite attainable) occurs concurrently with panicle initiation. Under excellent management even 100 fertile tillers per plant or even more can be achieved due to early transplanting and absence of die back of roots.
• Non lodging
• Big panicles
• More and well filled grain panicles and higher grain weight
• Resists insects because it allows rice to absorb soil nutrients naturally

Source: WASSAN-CSA-WWF Manual on SRI

Do-s and Don’t-s in SRI

1. Early Transplanting: Transplant 8-12 day old seedlings, with only two small leaves,( More tillering potential and root growth potential)
2. Careful Transplanting:Minimise trauma in transplanting. Remove plant from nursery with the seed, soil and roots carefully and place it in the field without plunging too deep into soil (More tillering potential)
3. Wide Spacing: plant single seedlings, not in clumps, and in a square pattern 25cm x 25cm apart or wider. Do not plant in rows. (More root growth potential)
4. Weeding and Aeration: use simple mechanical "rotating hoe" that churns up soil; 2 weedings required, (More root growth, due to reduced weed competition, and aeration of soil, giving roots more Oxygen and Nitrogen due to increased microbial activity) Each additional weeding after two rounds results in increased productivity up to 2 t/ha / weeding.
5. Water Management:regular water application to keep soil moist but not saturated, with intermittent dryings, alternating aerobic and anaerobic soil conditions (More root growth because it avoids root degeneration, enables better abosrption of nutrients from the soil).
6. Compost / FYM applied instead of or in addition to chemical fertilizer; 10 tons/ha (More plant growth because of better soil health and structure, and more balanced nutrient supply)

• Seed rate 2 kg/acre
• Nursery area 1 cent / acre
• Select healthy seeds
• Pre-sprouted seeds are sown on raised nursery bed
• Prepare nursery bed like the one prepared for garden crops
• Apply a layer of fine manure
• Spread sprouted seed sparsely
• Cover with another layer of manure
• Mulch with paddy straw
• Water carefully
• Banana leaf sheath may be used for easy lifting and transport of seedlings.

• Land preparation is not different from regular irrigated rice cultivation.
• Levelling should be done carefully so that water can be applied very evenly.
• Provide a canal at every 3m distance to facilitate drainage.
• Draw lines both ways at 25x25cm apart with the help of a marker and transplant at the intersection.

• 8-12 days old seedlings are transplanted
• Care should be taken during pulling out and transplanting of seedlings
• A metal sheet is inserted 4-5 inches below the seed bed and the seedlings along with soil lifted without any disturbance to the root.
• Seedlings are transplanted shallow and therefore establish quickly. Single seedling with seed and soil are transplanted by using index finger and thumb and gently placing them at the intersection of markings.
• Initially requires 10-15 persons to transplant one acre.

• The purpose of irrigation is just to wet the soil, just enough to saturate the soil with moisture
• Subsequent irrigation is only when soil develops fine cracks.
• Regular wetting and drying of soil results in increased microbial activity in the soil and easy availability of nutrients to the plants.

• Absence of standing water leads to more weed growth in SRI.
• Incorporate the weeds in the soil by moving the weeder between the rows
• Weeds close to the hills/tillers have to be removed by hand

• Higher yields - Both grain and straw
• Reduced duration (by 10 days)
• Lesser chemical inputs
• Less water requirement
• Less chaffy grain %
• Grain weight increased without change in grain size
• Higher head rice recovery
• Withstand cyclonic gales
• Cold tolerance
• Soil health improves through biological activity

• Higher labour costs in the initial years
• Difficulties in acquiring the necessary skills
• Not suitable when no irrigation source available

The Kadiramangalam System of Rice Intensification

(developed and practiced in the village by Mr S. Gopal  of the Cauvery Delta zone of Tamil Nadu State)

This system has been developed using SRI ideas and practices, such that it is suited to local conditions in the Cauvery Delta region.

• Concern of farmers in SRI method of planting : Very young seedlings (when planted as in SRI) will be desiccated by the intense sun and continuous wind.
• A potential solution to their problem : Transplanting very young seedlings in clumps of five for their first two weeks out of the nursery gives them some protection against sun and wind. Re-transplanting them singly after two weeks means that they are then stronger and able to grow vigorously with no mortality.
• Drawback in the method : Additional labour requirement for the second transplanting. However, farmers feel that the increased yield will cover the additional labor cost.
• Outcome : The yield obtained in this system was on an average 7.5 t/ha.

Techniques followed in the system

Nursery preparation

• A place with suitable irrigation and drainage facilities is needed to get good seedlings within 12 days.
• A nursery area of 100 sq. m. is prepared. This is all that is required for planting one hectare of crop (just 2.5 cents).
• A 300 gauge polythene sheet, 200ft in length and 1m in breadth, is required for raising enough seedlings for one hectare.
• A frame with dimensions of 1m length, 0.5m breath and 4cm height, is required for sowing the seeds.
• The frame is filled with press-mud or other compost.
• 5kg of sprouted seeds, treated with azospirillum and phosphobacterium, are required for sowing one hectare. These are planted at the rate of 45g per compartment, and the seeds are covered lightly with sieved press mud.
• Watering is done with a sprinkling can twice daily until the fifth day.
• A 0.5% urea spray is applied on the 8th day, dissolving 150g in 30 liters of water.
• Twelve-day-old seedlings, with their roots and seed sacs still kept in the cake, are taken to the main field for transplantation

Transplantation
First transplantation

• A small area of 8 cents in one corner of the field is prepared for transplanting the 12 day old young seedlings. It is enough for later transplanting one hectare.
• In this small portion, 4 to 5 seedling are planted per hill at a square spacing of 15cm between hills.
• On the 15th day, 0.5% urea spray is given.
• By 28 days, the paddy seedlings will be well-grown, 25cm height, with good root growth.

Second transplantation :

• At 30 days, the seedlings are carefully removed from these first hills and are separated and spread over the entire main field, with a spacing of 20x20cm between single plants.
• This work can be done for a hectare by 15 laborers in one day.

Advantages of double transplantation

• Seedlings are well grown, and there is zero mortality.
• As the seedlings are well grown, there is little or no weed problem.
• As the seedlings are tall, they are able to tolerate standing water from day one, which permits weed control by flooding.
• Separation of single seedlings is much easier.
• Establishment of the crop is much faster, and it is possible to work with the cono-weeder from the 10th day.
• No special training or effort is needed for this technology as all preparations can done be the same way that farmers usually practice rice cultivation.

Weed management
On the 10th day after this second transplanting, a cono-weeder is drawn along and across the rows of plants, being pushed 3 to 4 times in both directions. There is a saving of 10 labor-days/ha as this single weeding is sufficient.

Irrigation
Carry out irrigation so that water is applied only once the soil becomes dry, to keep it moist but never saturated. This reduces irrigation water requirements by about 500mm.

Fertiliser application

• First, phosphorous and potash fertilizer is applied as a basal dose.
• On the 15th day after cono weeding, 30kg of urea is applied.
• Again on the 30th day, 30kg/ha is applied.
• On the 45th day, 30kg/ha along with 30kg potash is applied.

Note: This information was provided from Kadiramangalam village, by Rajesh Kumar and Sourav Nayak who are the assigned agricultural extension personnel. They testified that this modified system of rice intensification developed and practiced in the village by Mr S. Gopal, a B.Sc graduate, is well suited for the Cauvery Delta zone of Tamil Nadu State.

Source : ciifad.cornell.edu

Related resources

1. Growing rice with less water: case studies from India
2. SRI - Baghpat district, Uttar Pradesh part-1
3. SRI - Baghpat district, Uttar Pradesh part-2