System of Rice Intensification

This article is about the establishment of rigorous protocols for crops that respond well to intensification of labour inputs in particular. This was always true. What was not true was the recent ability to share the knowledge of best practice around the world. That I knew how to maximize the productivity of my tomato plants never helped the chap down the road. Today I can share my skill and fussiness with every other tomato grower on earth.

Here this is been done for rice, and putting the applied science aside, this is no more than that. Today we can also explain what we are doing better.

Perhaps that is why my enthusiasm for biochar is so high. I know that it allows me to stabilize my soils and lets me tighten up the unknowns. Soils tend to do that anyway but biochar steps it up.

Most crop systems began as a best guess and was then refined over time. Bad practice was often carried on inadvertently. This is now able to end. The fact that we can hear about improved methods for rice husbandry is the biggest breakthrough of all.

I attached the item on methodology at the end.

It all comes down to having labor to supply to the planting task. My own plantings took these methods for granted, but someone had to be available to do them. Mass production does not have the capacity to handle a tender transplantable, in this case a mere two to three days old and certainly not hardened to handle the shock.

By allowing a tomato to grow to three inches and then drying them for a couple of days, I could transplant without any transplant loss at all with a vigorous resultant growth.

At least they are recognizing the importance of the root footprint.

The System of Rice Intensification known as SRI - also as le Systéme de Riziculture Intensive in French and la Sistema Intensivo de Cultivo Arrocero* (SICA) in Spanish — is a methodology for increasing the productivity of irrigated rice cultivation by changing the management of plants, soil, water and nutrients.
SRI practices lead to healthier, more productive soil and plants by supporting greater root growth and by nurturing the abundance and diversity of soil organisms. The agroecological principles that contribute to SRI effectiveness have good scientific bases. SRI concepts and methods have been successfully adapted to upland unirrigated rice, and they are now being extrapolated to other crops like millet, wheat and sugar cane.

SRI does not require the purchase of new seeds or the use of new high-yielding varieties. Although the highest yields with SRI have been obtained from improved varieties, most traditional or local varieties of rice respond well to SRI practices and command a higher market price. And while chemical fertilizer and agrochemicals can be applied with SRI, their use is not required as organic materials (compost, manure or any decomposed vegetation) can give good or even better results at low cost. Farmers report that when SRI methods are used correctly, rice plants are better able to resist damage from pests and diseases, reducing or eliminating need for agrochemical protection.

Because plant populations are greatly reduced with SRI, seed costs are cut by 80-90%, and because paddy fields are not kept continuously flooded, there are water savings of 25 to 50%, a major benefit in many places. However, cessation of flooding means that increased weeding is required. If this is done with soil-aerating implements like a rotating hoe, this cost has a benefit of enhanced crop production.

SRI does require skillful management of the factors of production and, at least initially, more labor, particularly for careful transplanting and for weeding. Since
yield increases are usually 50 to 100%, and possibly several times present levels, the returns to labor can be very great. The profitability of rice production can be greatly increased when yield goes up with a reduction in the costs of production. As farmers gain skill and confidence in SRI methods, their labor input in fact decreases, and over time SRI can even become labor saving compared with conventional rice-growing methods.

SRI is a work in progress, with improvements continually being made, including better implements and techniques that further reduce labor requirements. Farmers are encouraged to make their own improvements in SRI methods and to share experience within the farming community. Yield is the most evident (and controversial) feature of SRI, but many other considerations are also driving its spread around the world. Additional information on SRI benefits such as resistance to drought and storm damage, shorter time to maturity, and more milled rice resulting when SRI paddy is processed can be found in a paper on:

Features of the System of Rice Intensification apart from Increases in Yield.


SRI increases rice production and raises the productivity of land, labor, water and capital through different practices for managing:

Rice plants - Seedlings are transplanted: very young -- usually just 8-12 days old, 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 their 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.

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