SRI METHODOLOGIES

The System of Rice Intensification, known as SRI — le Système de Riziculture Intensive in French and la Sistema Intensivo de Cultivo Arrocero (SICA) in Spanish — is a climate-smart, agroecological methodology for increasing the productivity of rice and more recently other crops by changing the management of plants, soil, water and nutrients.

SRI Principles

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

Based on these principles, farmers can adapt recommended SRI practices to respond to their agroecological and socioeconomic conditions. Adaptations are often undertaken to accommodate changing weather patterns, soil conditions, labor availability, water control, access to organic inputs, and the decision whether to practice fully organic agriculture or not. The most common SRI practices for irrigated rice production are summarized in the following section.

In addition to irrigated rice, the SRI principles have been applied to rainfed rice and to other crops, such as wheatsugarcanetefffinger milletpulses, showing increased productivity over current conventional planting practices. When SRI principles are applied to other crops, we refer to it as the System of Crop Intensification or SCI (see SCI sectionof the website for details).

Recommended SRI Management Practices for Irrigated Conditions

  • Rice Plants › seedlings are transplanted:
    • very young › at the 2 leaf-stage, usually between 8 and12 days old*
    • carefully and quickly › protecting the seedlings’ roots and minimizing the transplanting shock
    • singly › one plant 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 › 25×25 cm or wider in good quality soil

*Note: Adaptations for direct-seeding and mechanical transplanting have been undertaken in a number of countries.

  • Soil › The soil is enriched with organic matter to improve soil structure, nutrient and water holding capacity, and favor soil microbial development. Organic matter represents the base fertilization for the crop and is complemented if needed by fertilizer.
  • Water › Only a minimum of water is applied during the vegetative growth period. A 1-2 cm layer of water is introduced into the paddy, followed by letting the plot dry until cracks become visible, at which time another thin layer of water is introduced. During flowering a thin layer of water is maintained, followed by alternate wetting and drying in the grain filling period, before draining the paddy 2-3 weeks before harvest. This method is called ‘intermittent irrigation’ or ‘Alternative Wetting and Drying’ (AWD). Some farmers irrigated their fields every evening, other leave their fields drying out over 3-8 days, depending on soil and climate conditions.
  • Nutrients  As soils are improved through organic matter additions, many nutrients become available to the plant from the organic matter. Additionally the soil is also able to hold more nutrients in the rooting zone and release them when the plants need them. Depending on the yield level and on the farming system, some farmers use exclusive organic fertilization for their SRI plots. The majority of farmers complement the organic matter amendment with chemical fertilizers, most often urea, in order to achieve a balanced fertilization of the crop.
  • Weeds › While avoiding flooded conditions in the rice fields, weeds grow more vigorously, and need ideally be kept under control at an early stage. A rotary hoe – a simple, inexpensive, mechanical push-weeder – is most often used starting at 10 days after transplanting, repeated ideally every 7-10 days until the canopy is closing (up to 4 times). The weeder has multiple functions and benefits. i) It incorporates the weeds into the soil, where they decompose and their nutrients can be recycled, ii) it provides a light superficial tillage and aerates the soil, ii) it stimulates root growth by root pruning, iii) it makes nutrients newly available to the plant by mixing water with organic matter enriched top soil. A re-greening effect of the plants can be observed 1-2 days after weeding, and iv) it redistributes water across the plot, contributing to a continuous leveling of the plot and eliminating water patches in lower laying areas in the field that create anaerobic conditions for the plants. The use of the weeder contributes to homogeneous field conditions, creating a uniform crop stand and leading to increased yields. For more information see WASSAN Weeder Compendium, our YouTube playlist for weeders (manual and mechanized) and short weeder slide presentation for more on weeders.
READ:  FARMERS FIELD SCHOOLS: APPLICATIONS AND APPROACH

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