Abstract
A recent transition in rice straw management, from open‐field burning to soil incorporation in combination with winter‐fallow flooding, has led to uncertainty in evaluating long‐term N fertility. A 2‐yr field study of 15 N‐labeled fertilizer and crop residue was initiated in the fourth year of a rice straw management trial to examine the impacts of winter flooding and straw management on N fertilizer immobilization and crop uptake. After six seasons of residue incorporation and winter flooding, no effect on total soil C or N was observed. During the fifth and sixth year of the field study, microbial biomass C and N were greater for straw incorporation than for straw burned. Microbial biomass contained a sizable portion of soil‐recovered 15 N fertilizer after the first (23%) and second (10%) crop season of the 15 N study. The half‐life of the 15 N in the biomass ranged from 0.55 to 0.87 yr. One year after 15 N‐fertilizer application, greater recovery of 15 N in the soil from straw incorporation versus burning (22.2 versus 18.7%) resulted in a slight increase in residual fertilizer N recovery in grain in the second growing season of the 15 N study. Increased soil 15 N recovery 1 yr after fertilizer application in the straw incorporation treatment, however, was offset by higher grain recovery of 15 N in the burned treatment during the first growing season. Hence, the net result of these competing soil and plant sinks for fertilizer N led to similar 15 N losses after 2 yr (50.3 ± 2.2%) under burned and incorporated straw. The cumulative effects of straw incorporation resulted in greater net N mineralization, an increase in microbial biomass N, and greater recovery of 15 N in soil one year after application. Clearly, an active, labile N pool was formed when straw was incorporated that led to a reduction in fertilizer N dependency for rice.
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Claims 13
Claim · model-written summary
Residue incorporation and winter flooding had no observed effect on total soil C or N after six seasons.
- Taxon
- Rice
Oryza sativat0 - Treatment
- residue incorporation and winter floodinge0
- Outcome
- total soil C or Ne0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After six seasons of residue incorporation and winter flooding, no effect on total soil C or N was observed”
t0“Rice”
Claim · model-written summary
Microbial biomass C and N were greater under straw incorporation than burning during years five and six.
- Taxon
- RiceOryza sativat0
- Treatment
- straw incorporatione0
- Outcome
- microbial biomass C and Ne0
- Direction
- greatere0
- Comparator
- straw burnede0
- Setting
- field studye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the fifth and sixth year of the field study, microbial biomass C and N were greater for straw incorporation than for straw burned”
t0“Rice”
Claim · model-written summary
Microbial biomass contained 23% of soil recovered labeled fertilizer after the first crop season.
- Taxon
- RiceOryza sativat0
- Outcome
- soil‐recovered 15 N fertilizere0
- Value
- 23%e0
- Qualifier
- firste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Microbial biomass contained a sizable portion of soil‐recovered 15 N fertilizer after the first (23%) and second (10%) crop season”
t0“Rice”
Claim · model-written summary
Microbial biomass contained 10% of soil recovered labeled fertilizer after the second crop season.
- Taxon
- RiceOryza sativat0
- Outcome
- soil‐recovered 15 N fertilizere0
- Value
- 10%e0
- Qualifier
- seconde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Microbial biomass contained a sizable portion of soil‐recovered 15 N fertilizer after the first (23%) and second (10%) crop season”
t0“Rice”
Claim · model-written summary
Labeled nitrogen in biomass had a half life of 0.55 to 0.87 yr.
- Taxon
- RiceOryza sativat0
- Outcome
- half‐life of the 15 N in the biomasse0
- Value
- 0.55 to 0.87 yre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The half‐life of the 15 N in the biomass ranged from 0.55 to 0.87 yr”
t0“Rice”
Claim · model-written summary
After one year, soil recovery of labeled N was 22.2% with incorporation versus 18.7% with burning.
- Taxon
- RiceOryza sativat0
- Treatment
- straw incorporatione0
- Outcome
- recovery of 15 N in the soile0
- Direction
- greatere0
- Value
- 22.2e0
- Qualifier
- 18.7%e0
- Comparator
- burninge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“greater recovery of 15 N in the soil from straw incorporation versus burning (22.2 versus 18.7%)”
t0“Rice”
Claim · model-written summary
Incorporation slightly increased residual fertilizer N recovery in grain in the second season.
- Taxon
- RiceOryza sativat0
- Organ / stage
- graine0
- Treatment
- straw incorporatione1
- Outcome
- residual fertilizer N recovery in graine0
- Direction
- increasee0
- Comparator
- burninge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulted in a slight increase in residual fertilizer N recovery in grain in the second growing season”
e1“straw incorporation versus burning”
t0“Rice”
Claim · model-written summary
Burning had higher grain recovery of labeled N in the first season.
- Taxon
- RiceOryza sativat0
- Treatment
- burned treatmente0
- Outcome
- grain recovery of 15 Ne0
- Direction
- highere0
- Comparator
- straw incorporation treatmente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher grain recovery of 15 N in the burned treatment during the first growing season”
e1“straw incorporation treatment”
t0“Rice”
Claim · model-written summary
Labeled N losses after two years were similar under burned and incorporated straw at 50.3 ± 2.2%.
- Taxon
- RiceOryza sativat0
- Treatment
- incorporated strawe0
- Outcome
- 15 N lossese0
- Direction
- similare0
- Value
- 50.3 ± 2.2%e0
- Comparator
- burnede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“similar 15 N losses after 2 yr (50.3 ± 2.2%) under burned and incorporated straw”
t0“Rice”
Claim · model-written summary
Straw incorporation increased net N mineralization.
- Taxon
- RiceOryza sativat0
- Treatment
- straw incorporatione0
- Outcome
- net N mineralizatione0
- Direction
- greatere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The cumulative effects of straw incorporation resulted in greater net N mineralization, an increase in microbial biomass N, and greater recovery of 15 N in soil one year after application”
t0“Rice”
Claim · model-written summary
Straw incorporation increased microbial biomass N.
- Taxon
- RiceOryza sativat0
- Treatment
- straw incorporatione0
- Outcome
- microbial biomass Ne0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“straw incorporation resulted in greater net N mineralization, an increase in microbial biomass N”
t0“Rice”
Claim · model-written summary
Straw incorporation increased soil labeled N recovery one year after application.
- Taxon
- RiceOryza sativat0
- Treatment
- straw incorporatione0
- Outcome
- recovery of 15 N in soile0
- Direction
- greatere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“straw incorporation resulted in greater net N mineralization, an increase in microbial biomass N, and greater recovery of 15 N in soil one year after application”
t0“Rice”
Claim · model-written summary
The authors infer that straw incorporation formed an active labile N pool and reduced rice fertilizer N dependency.
- Taxon
- riceOryza sativae0
- Treatment
- straw was incorporatede0
- Outcome
- fertilizer N dependencye0
- Direction
- reductione0
- Qualifier
- active, labile N poole0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an active, labile N pool was formed when straw was incorporated that led to a reduction in fertilizer N dependency for rice”
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See all 22 papers →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.