Review of SRI Presentations

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Review of SRI Presentations
Farmers SRI field, Madagascar. Yield 12.4 t/ha

• Erick Fernandes
• Cornell University
• ecf3_at_cornell.edu

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Country Presentations

• 17 Country presentations
• Africa 3
• Asia 4
• S.E. Asia 7
• Americas 3
• With the exception of Madagascar, all other
  country reports are based on less than 3 years of
  data

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Elements of SRI

• Careful transplanting of young seedlings
• (8-15 days)
• 1 or 2 seedlings per hill
• Alternating flooding and drying during vegetative
  phase
  
• Weeding and aeration
• Compost application

4
Total Factor Productivity

• Yields
• Labor
• Soils Roots
• Water
• Seeds
• Food quality
• Environmental benefits

5
Yields

• ¾ of studies confirm a significant yield
  advantage in SRI vs conventional rice
  
• For yields below 8 t/ha, yield increases due to
  SRI were between 10-50.
  
• Madagascar reports super yields ranging from
  17-23 t/ha relative to a national average of t/ha
  
• Madagascar data show 55 fertile tillers (70
  required for very high yields)
  
• Yield increases are most frequently observed on
  farmers fields rather than on station

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Yields II

• Although SRI results in increased yields for both
  traditional and improved varieties, several
  studies reported that some varieties respond
  better to SRI than others.
• 120-140 day varieties may respond best to SRI.
  Very short or long duration varieties appear to
  respond less.
  
• Although suggested spacings for SRI vary between
  25x25 cm to 35x35 cm, high yields (13 t/ha) have
  also been reported at 45x45 cm. There is most
  likely a significant interaction between variety
  and spacing.

8
Labor

• Most studies report that SRI is more labor
  demanding than conventional rice. (Three studies
  reported that SRI required less labor).
  
• Extra labor components land preparation, careful
  planting of small seedlings, water and weed
  management)

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Soils Roots

• Effect of soil texture is still uncertain
• It is hypothesized that soil biological factors
  are very important for SRI synergy.
  
• Only 3 studies looked at root volume and root
  activity or soil microbial dynamics.
  
• Relatively little detailed soil data is
  available. Important for nutrient budgets as
  yields and nutrient harvests increases.

10
Compost Pits

• Crop residues
• Cattle manure urine
• Legume prunings
• Grass clippings

End of cropping season
Start of cropping season
11
SRI Plants
Traditional Rice
12
Water

• Flooding and draining of water requires good
  access to and control of water
  
• A few studies carried out detailed measurements
  and report significant water savings relative to
  conventionally flooded rice.
  
• Weed pressure increases with draining and wide
  spacings.
  
• In one study, soil drying and cracking yielded
  less than continuously moist soil.
  

13
Seeds

• Most studies reported a significant saving in the
  amount of seed used to establish the rice field.
  

14
Food Environmental Impacts

• Fewer chemical and pesticide inputs can translate
  into healthier food
  
• Alternate flooding and draining can reduce CH4
  emissions but result in significant increases in
  NOx emissions. The effect of nitrous oxide is
  35x greater than CH4.

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Issues to Consider

• Better descriptions of the experiments
• Who is doing what? Metadata
• Where (georeferenced data sets)
• To tap into other databases (soils, vegetation)
• Replication of field trials (on farm, on station)
  to get a better handle of variability observed
  
• Socioeconomic studies to better characterize
  tradeoffs
  

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Issues to Consider II

• What is special about the sites where we observe
  SRI yields 10 t/ha?
  
• Soils, long-term management, soil biology?
• Should we have a standard experiment that is
  conducted at selected sites across the regions?