Synonyms: Systeme de Riziculture Intensive (SRI) = System of Rice Intensification = la Sistema Intensivo de Cultivo Arrocero (SICA).
What Is It? Intensive rice culture was invented by a French agronomist, Friar Henri de Laulanie de Saint Croix, Society of Jesuits, in 1983 while working on agricultural development projects in Madagascar.
The basic idea is to space individual plants widely so they grow as many tillers as possible. More tillers = more grain per plant = up to 7 times average yields.
SRI is directly opposite California practice of crowding 1,000,000 plants per acre (23 plants per square foot). Closely spaced plants have few tillers and produce less grain per plant, but yields are high because there are so many plants per acre.
Both methods work but SRI is better suited to developing countries where labor is cheap and farmers cannot afford expensive machinery and agricultural chemicals needed for conventional rice agronomy.
Traditional rice culture uses flooded paddies, 21 to 30 day old transplants, and close spacing with 3 or 4 plants per hill. Transplants are shoved into the mud without regard to root orientation or planting depth. Rice tolerates these practices but does not thrive. Consequently, yields are greatly reduced.
Intensive rice culture avoids flooded fields. Transplants are set at the 2-leaf stage when 8 to 12 days old. Individual plants are widely spaced with crowns at ground level. Roots are carefully oriented vertically or horizontally. Transplanting is done quickly. These practices greatly increase the number of productive tillers resulting in much higher yields.
Typical SRI plants have 50 to 100 tillers. Most panicles bear 100 to 200 seeds. Under ideal conditions yields can exceed 20 metric tons per hectare ~ 8.9 tons per acre.
SRI methods work with most types of upland or lowland rice, West African (Oryza glaberrima) or Asian species (Oryza sativa). Best results are obtained from long season oriental varieties.
How To Do It: Following are detailed agronomic practices for intensive rice cultivation.
>>> Need 7 to 8 kilograms of seed rice per hectare ~ 6 to 7 pounds per acre ~ 100 grams per square meter ~ 3 scale ounces per square yard of nursery bed.
>>> Prepare salt water solution of sufficient density to float a fresh chicken egg. Mix seed rice with salt water. Discard any rice that floats. Save rice that sinks. Drain salt water from seed rice. Wash seed rice thoroughly 4 times to remove salt. Soak seed rice in fresh water 24 hours to speed germination. If desired, seed may be pre-germinated in a warm place: Spread soaked seed on wet burlap bags then cover with more wet burlap. Seed is ready for planting when the first root on any seed appears.
>>> Prepare nursery bed of 100 to 150 square meters size per hectare of rice field ~ 50 to 75 square yards per acre. Rule-of-Thumb: Nursery area = 1% of field size. Nursery beds should only be 1 meter ~ 1 yard wide so they can be tended by hand. For best results locate nursery beds next to rice fields to reduce transplanting time.
>>> Place plastic sheeting or banana leaves on soil surface to keep rice roots compact. Fill nursery beds with compost 10 to 15 centimeters ~ 4 to 6 inches deep. Spread seed sparsely = 2.5 centimeters = 1 inch apart on soil surface. Cover seed thinly with 1 to 2 centimeters ~ 1/2 to 3/4 inch of compost then mulch lightly with straw or banana leaves. Water 2 times daily to keep seeds moist.
>>> If desired, seed can be planted into individual soil cubes, peat pots, or other biodegradable containers that will not restrict root growth. Alternatively, rice may be direct seeded into prepared fields. Plant not more than 2 seeds per hill. Space each seed 5 centimeters ~ 2 inches apart. Thin seedlings to 1 per hill immediately plants reach 2-leaf stage = 8 to 12 days after emergence. Cut off excess plants at soil surface to prevent root damage to remaining seedlings.
>>> Fertilize fields with composted manure or other organic fertilizers then plow. Recommended rate = 5 to 10 metric tons per hectare = 1/2 to 1 kilogram per square meter ~ 2.25 to 4.5 tons per acre ~ 4,500 to 9,000 pounds per acre ~ 1 to 2 pounds per square yard. Alternatively, grow a nitrogen-fixing legume like velvet bean (Mucuna pruriens) then plow, roller-crimp, or mow when cover crop flowers.
>>> Irrigate field with 1.25 to 2.5 centimeters ~ 1/2 to 1 inch of water to moisten soil. Do not flood field more than 24 hours if practical. Waterlogged soils reduce yields.
>>> Mark moist soil with a grid pattern to ensure proper plant spacing. In hot tropical climates near sea level space individual plants 30 centimeters ~ 12 inches apart. At higher elevations (1,200 meters ~ 3,900 feet above sea level or 1,500 meters ~ 4,900 feet on the equator) space rice transplants closer together = 25 centimeters ~ 10 inches apart. Wide plant spacing is essential for maximum tiller growth = higher yields. Best yields are obtained on highly fertile, equatorial lowland soils when plants are spaced 50 x 50 centimeters ~ 20 inches apart.
>>> Transplant seedlings in their 2-leaf stage = when plants are 8 to 12 days old. Do not plant seedlings older than 15 days. Young transplants grow many tillers which increase yields. Old transplants grow few tillers.
>>> Plant 1 seedling only at each grid intersection. Multiple seedlings crowd each other and decrease yields.
>>> Transplant seedlings quickly = not more than 15 minutes after lifting plants from nursery bed. Fast planting reduces shock and increases yields.
>>> Transplant seedlings carefully = 2 to 3 centimeters ~ 3/4 to 1 1/4 inches deep with roots oriented vertically or horizontally. Do not turn roots up (like a hook) or yields will fall. Do not plant deeply or yields will drop.
Rice plants are like strawberries. Both are highly sensitive to planting depth. Rice grows few tillers if seeded or transplanted too deeply. Try to set plants at the same depth they grew in the nursery. Rice crowns = growing points should be level with soil surface.
>>> Irrigate fields with 1.25 to 2.25 centimeters ~ 1/2 to 1 inch of water every 7 to 10 days as needed. Wait until soil cracks before applying more water. Do not flood field for more than 24 hours if practical. Standing water reduces yields. More oxygen to roots increases yields.
>>> Fertilize field with compost 30 days after transplanting seedlings, then again 60 days after transplanting. Recommended rate = 5 to 10 metric tons per hectare = 1/2 to 1 kilogram per square meter ~ 2.25 to 4.5 tons per acre = 4,500 to 9,000 pounds per acre ~ 1 to 2 pounds per square yard. High soil fertility is needed for maximum yields.
Adjust fertilizer rates as necessary. Tall rice varieties lodge = fall over if plants absorb too much nitrogen. Yields drop if plants do not have sufficient nutrients during critical phases of vegetative growth and reproduction.
>>> Weed field 7 to 10 days after transplanting seedlings. Use a rotary weeder. Weed field up to 4 times until rice canopy closes. Each weeding increases yields by 1 to 2 metric tons per hectare = 890 to 1,780 pounds per acre.
>>> Stop irrigation 15 days before harvest. Dry soil is necessary to ripen grain and make harvesting easier.
>>> Typical SRI yields = 1 kilogram of grain per square meter = 10 metric tons per hectare ~ 8,900 pounds = 4.45 tons per acre. With good management yields can double.
>>> SRI Record Yield (crop year 2015) = 22.4 metric tons per hectare = 9.9755 tons per acre = 19,951 pounds per acre = 443 bushels per acre (45 pounds per bushel) = 7.37 ounces per plant at 208 x 208 = 43,264 plants per acre (1 plant per square foot).
For best results follow SRI directions carefully. Small changes in agronomic practices can have dramatic effects on tiller number, seeds per panicle, and seed weight.
Related Publications: Crop Rotation Primer; No-Till Subsistence Grain Farming; Pelleted Seed Primer; and Planting Maize with Living Mulches.
For More Information: Contact the Author directly if you have any questions or need additional information about intensive grain culture systems.
Please visit: http://www.worldagriculturesolutions.com — or — mail your questions to: World Agriculture Solutions, 413 Cedar Drive, Moon Township, Pennsylvania 15108 United States of America — or — send an e-mail to: firstname.lastname@example.org
Cornell University hosts a comprehensive SRI website at: SRI Rice Online: http://sririce.org
E-mail Address: email@example.com
The original SRI papers by Friar Laulanie are available both online and in the scientific journal Tropicultura:
Technical Presentation of the System of Rice Intensification, Based on Katayama’s Tillering Model. Henri de Laulanie. 1993 Tropicultura 13 : 1.
Intensive Rice Farming in Madagascar. Henri de Laulanie. 2011 Tropicultura 29 : 3 (183 – 187).
About The Author: Mr. Koperek is a plant breeder who farms in Pennsylvania during summer and Florida during winter. Growing 2 generations yearly speeds development of new crop varieties.