Abstract
Global rice agriculture will be increasingly challenged by water scarcity, while at the same time changes in demand (e.g. changes in diets or increasing demand for biofuels) will feed back on agricultural practices. These factors are changing traditional cropping patterns from double-rice cropping to the introduction of upland crops in the dry season. For a comprehensive assessment of greenhouse gas (GHG) balances, we measured methane (CH4 )/nitrous oxide (N2 O) emissions and agronomic parameters over 2.5 years in double-rice cropping (R-R) and paddy rice rotations diversified with either maize (R-M) or aerobic rice (R-A) in upland cultivation. Introduction of upland crops in the dry season reduced irrigation water use and CH4 emissions by 66-81% and 95-99%, respectively. Moreover, for practices including upland crops, CH4 emissions in the subsequent wet season with paddy rice were reduced by 54-60%. Although annual N2 O emissions increased two- to threefold in the diversified systems, the strong reduction in CH4 led to a significantly lower (P < 0.05) annual GWP (CH4 + N2 O) as compared to the traditional double-rice cropping system. Measurements of soil organic carbon (SOC) contents before and 3 years after the introduction of upland crop rotations indicated a SOC loss for the R-M system, while for the other systems SOC stocks were unaffected. This trend for R-M systems needs to be followed as it has significant consequences not only for the GWP balance but also with regard to soil fertility. Economic assessment showed a similar gross profit span for R-M and R-R, while gross profits for R-A were reduced as a consequence of lower productivity. Nevertheless, regarding a future increase in water scarcity, it can be expected that mixed lowland-upland systems will expand in SE Asia as water requirements were cut by more than half in both rotation systems with upland crops.
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Claims 10
Claim · model-written summary
Upland crops in the dry season reduced irrigation water use by 66-81%.
- Taxon
- rice
Oryza sativat0 - Treatment
- upland crops in the dry seasone0
- Outcome
- irrigation water usee0
- Direction
- reducede0
- Value
- 66-81%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Introduction of upland crops in the dry season reduced irrigation water use and CH4 emissions by 66-81% and 95-99%, respectively.”
t0“tropical rice rotation systems”
Claim · model-written summary
Upland crops in the dry season reduced CH4 emissions by 95-99%.
- Taxon
- riceOryza sativat0
- Treatment
- upland crops in the dry seasone0
- Outcome
- CH4 emissionse0
- Direction
- reducede0
- Value
- 95-99%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Introduction of upland crops in the dry season reduced irrigation water use and CH4 emissions by 66-81% and 95-99%, respectively.”
t0“tropical rice rotation systems”
Claim · model-written summary
Upland crop practices reduced subsequent wet-season paddy rice CH4 emissions by 54-60%.
- Taxon
- paddy ricee0
- Treatment
- practices including upland cropse0
- Outcome
- CH4 emissionse0
- Direction
- reducede0
- Value
- 54-60%e0
- Qualifier
- subsequent wet seasone0
Not reportedComparator
Verbatim
e0“for practices including upland crops, CH4 emissions in the subsequent wet season with paddy rice were reduced by 54-60%”
Claim · model-written summary
Annual N2 O emissions increased two- to threefold in diversified systems.
- Taxon
- riceOryza sativat0
- Treatment
- diversified systemse0
- Outcome
- annual N2 O emissionse0
- Direction
- increasede0
- Value
- two- to threefolde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“annual N2 O emissions increased two- to threefold in the diversified systems”
t0“tropical rice rotation systems”
Claim · model-written summary
Annual GWP was significantly lower in upland-crop systems than in traditional double-rice cropping.
- Taxon
- riceOryza sativat0
- Outcome
- annual GWP (CH4 + N2 O)e0
- Direction
- lowere0
- Comparator
- traditional double-rice cropping systeme0
Not reportedTreatment
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the strong reduction in CH4 led to a significantly lower (P < 0.05) annual GWP (CH4 + N2 O) as compared to the traditional double-rice cropping system”
t0“tropical rice rotation systems”
Claim · model-written summary
The R-M rotation lost soil organic carbon.
- Taxon
- riceOryza sativat0
- Treatment
- R-M systeme0
- Outcome
- SOC losse0
- Direction
- losse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Measurements of soil organic carbon (SOC) contents before and 3 years after the introduction of upland crop rotations indicated a SOC loss for the R-M system”
t0“tropical rice rotation systems”
Claim · model-written summary
Soil organic carbon stocks were unaffected in the other rotation systems.
- Taxon
- riceOryza sativat0
- Outcome
- SOC stockse0
- Direction
- unaffectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for the other systems SOC stocks were unaffected”
t0“tropical rice rotation systems”
Claim · model-written summary
R-M and R-R had similar gross profit spans.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Economic assessment showed a similar gross profit span for R-M and R-R”
t0“tropical rice rotation systems”
Claim · model-written summary
R-A gross profits were reduced because of lower productivity.
- Taxon
- riceOryza sativat0
- Treatment
- R-Ae0
- Outcome
- gross profitse0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gross profits for R-A were reduced as a consequence of lower productivity”
t0“tropical rice rotation systems”
Claim · model-written summary
Both rotation systems with upland crops cut water requirements by more than half.
- Taxon
- riceOryza sativat0
- Outcome
- water requirementse0
- Direction
- cute0
- Value
- more than halfe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“water requirements were cut by more than half in both rotation systems with upland crops”
t0“tropical rice rotation systems”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.