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Rice plants - Seedlings are transplanted:

• very young -- usually just 8-12 days old, with just two small leaves
  
• carefully and quickly to have minimum trauma to the roots
  
• singly, only one per hill instead of 3-4 together to avoid root competition
  
• widely spaced to encourage greater root and canopy growth
  
• in a square grid pattern, 25x25 cm or wider -- 30x30 cm or 40x40 cm, even up to 50x50 cm with the best quality soil

Soil - This is kept moist but well-drained and aerated, with good structure and enough organic matter to support increased biological activity. The quality and health of the soil is the key to best production.

Water - Only a minimum of water is applied during the vegetative growth period, and then only a thin layer of water is maintained on the field during the flowering and grain filling stage. Alternatively, to save labor time, some farmers flood and drain (dry) their fields in 3-5 day cycles with good results. Best water management practices depend on soil type, labor availability and other factors, so farmers should experiment on how best to apply the principle of having moist but well-drained soil while thier rice plants are growing.

Nutrients - Soil nutrient supplies should be augmented, preferably with compost, made from any available biomass. Better quality compost such as with manure can give additional yield advantages. Chemical fertilizer can be used and gives better results than with no nutrient amendments, but it contributes less to good soil structure and active microbial communities in the rhizosphere than does organic matter. At least initially, nutrient amendments may not be necessary to achieve higher yields with the other SRI practices, but it is desirable to build up soil fertility over time. Rice-root exudation, greater with SRI, enhances soil fertility.

Weeds - Since weeds become a problem in fields that are not kept flooded, weeding is necessary at least once or twice, starting 10-12 days after transplanting, and preferably 3 or 4 times before the canopy closes. Using a rotary hoe -- a simple, inexpensive, mechanical push-weeder has the advantage of aerating the soil at the same time that weeds are eliminated. (They are left in the soil to decompose so their nutrients are not lost.) Additional weedings beyond two increase yield more than enough under most conditions to justify the added labor costs. A variety of available weeders are shown in the WASSAN publication "Weeders: A Reference Compendium."

For more details, see one of the "manuals" on SRI that are available in Cambodian, English, French, Nepali, Spanish, Thaiand other languages. ("Manuals" is put in quotation marks because we do not think of or promote SRI as a technology with a fixed set of practices; it is not a "package" to be adopted in a fixed way.) There are a number of variations in the practices that should be considered and evaluated under field conditions.