Abstract
Rice systems provide a major source of calories for more than half of the world’s population; however, they also use more water than other major crops. Alternate wetting and drying (AWD) is an irrigation practice (introduction of unsaturated soil conditions during the growing season) that can reduce water inputs in rice, yet it has not been widely adopted, in part, due to the potential for reduced yields. We conducted a meta-analysis to: 1) quantify the effect of AWD on rice yields and water use; and 2) to identify soil properties and management practices that favor AWD yields and promote low water use relative to continuous flooding (CF- control). We analyzed 56 studies with 528 side-by-side comparisons of AWD with CF. Overall, AWD decreased yields by 5.4%; however under Mild AWD (i.e. when soil water potential was ≥ −20 kPa or field water level did not drop below 15 cm from the soil surface), yields were not significantly reduced in most circumstances. In contrast, Severe AWD (when soils dried beyond −20 kPa) resulted in yield losses of 22.6% relative to CF. These yield losses were most pronounced in soils with pH ≥ 7 or carbon < 1% or when AWD was imposed throughout the season. While water use was lowest under Severe AWD, under Mild AWD water use was reduced by 23.4% relative to CF. Our findings both highlight the potential of AWD to reduce water inputs without jeopardizing yield as well as the conditions under which these results can be realized.
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Claims 6
Claim · model-written summary
Overall alternate wetting and drying decreased rice yields by 5.4%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“Overall, AWD decreased yields by 5.4%”
Claim · model-written summary
Mild alternate wetting and drying did not significantly reduce rice yields in most circumstances.
- Taxon
- Rice
Oryza sativat0 - Treatment
- Mild AWDe0
- Outcome
- yieldse0
- Direction
- not significantly reducede0
- Qualifier
- in most circumstancese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“under Mild AWD (i.e. when soil water potential was ≥ −20 kPa or field water level did not drop below 15 cm from the soil surface), yields were not significantly reduced in most circumstances”
Claim · model-written summary
Severe alternate wetting and drying reduced rice yield by 22.6% relative to continuous flooding.
- Taxon
- RiceOryza sativat0
- Treatment
- Severe AWDe0
- Outcome
- yielde0
- Direction
- lossese0
- Value
- 22.6%e0
- Qualifier
- when soils dried beyond −20 kPae0
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“Severe AWD (when soils dried beyond −20 kPa) resulted in yield losses of 22.6% relative to CF”
Claim · model-written summary
Yield losses were greatest with soil pH at least 7, carbon below 1%, or season-long AWD.
- Taxon
- RiceOryza sativat0
- Treatment
- AWDe0
- Outcome
- yield lossese0
- Direction
- most pronouncede0
- Qualifier
- soils with pH ≥ 7 or carbon < 1% or when AWD was imposed throughout the seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“These yield losses were most pronounced in soils with pH ≥ 7 or carbon < 1% or when AWD was imposed throughout the season”
Claim · model-written summary
Water use was lowest under severe AWD.
- Taxon
- RiceOryza sativat0
- Treatment
- Severe AWDe0
- Outcome
- water usee0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“water use was lowest under Severe AWD”
Claim · model-written summary
Mild AWD reduced water use by 23.4% relative to continuous flooding.
- Taxon
- RiceOryza sativat0
- Treatment
- Mild AWDe0
- Outcome
- water usee0
- Direction
- reducede0
- Value
- 23.4%e0
- Comparator
- CFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Rice”
e0“under Mild AWD water use was reduced by 23.4% relative to CF”
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