Abstract
Abstract Previous studies using artificial barriers at selected depths have shown the importance of N supply from soil below 15 cm to rice ( Oryza sativa L.). Subsoil N availability and its use by wetland rice, however, have not been evaluated under normal field conditions. We examined distribution and availability of 2 M KCl‐extractable N in 0‐ to 15‐, 15‐ to 30‐, and 30‐ to 45‐cm layers of a submerged Alfisol during three successive crop seasons, as influenced by the depth of tillage imposed at the outset of the experiment. Mineral N availability in the 0‐ to 45‐cm profile and rice N uptake in the first season were significantly higher (20–25 kg ha −1 higher mineral N and 16–18 kg ha −1 higher crop N uptake) with tillage to a depth of 40 cm than to 15 or 25 cm, the increased N supply originating largely from the 15‐ to 30‐cm layer. In two following seasons, tillage to 40 cm gave the highest mineral N in the subsoil layers, and increased rice N uptake by 12 to 14 kg ha −1 , compared with tillage to 15 cm. The beneficial effects of deep tillage were attributed to the elimination of mechanical impedence to root proliferation, and lower susceptibility of subsoil N to various loss mechanisms. Initial and final analyses of Kjeldahl N in the soil profile indicated no adverse effect of practicing 40‐cm‐deep tillage once in three seasons on soil N fertility. Further study is needed to determine optimum depth and frequency of primary tillage for different soil types to enhance N use efficiency.
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Claims 8
Claim · model-written summary
In the first season, 40 cm tillage increased soil mineral N availability by 20–25 kg ha −1 relative to 15 or 25 cm.
- Taxon
- rice
Oryza sativae0 - Treatment
- tillage to a depth of 40 cme0
- Outcome
- Mineral N availability in the 0‐ to 45‐cm profilee0
- Direction
- highere0
- Value
- 20–25 kg ha −1e0
- Comparator
- 15 or 25 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mineral N availability in the 0‐ to 45‐cm profile and rice N uptake in the first season were significantly higher (20–25 kg ha −1 higher mineral N and 16–18 kg ha −1 higher crop N uptake) with tillage to a depth of 40 cm than to 15 or 25 cm”
Claim · model-written summary
In the first season, 40 cm tillage increased rice N uptake by 16–18 kg ha −1 relative to 15 or 25 cm.
- Taxon
- riceOryza sativae0
- Treatment
- tillage to a depth of 40 cme0
- Outcome
- rice N uptakee0
- Direction
- highere0
- Value
- 16–18 kg ha −1e0
- Comparator
- 15 or 25 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mineral N availability in the 0‐ to 45‐cm profile and rice N uptake in the first season were significantly higher (20–25 kg ha −1 higher mineral N and 16–18 kg ha −1 higher crop N uptake) with tillage to a depth of 40 cm than to 15 or 25 cm”
Claim · model-written summary
In the following seasons, 40 cm tillage produced the highest subsoil mineral N.
- Taxon
- RiceOryza sativat0
- Treatment
- tillage to 40 cme0
- Outcome
- mineral N in the subsoil layerse0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In two following seasons, tillage to 40 cm gave the highest mineral N in the subsoil layers”
t0“Rice”
Claim · model-written summary
In the following seasons, 40 cm tillage raised rice N uptake by 12 to 14 kg ha −1 relative to 15 cm.
- Taxon
- riceOryza sativae0
- Treatment
- Tillage Deptht0
- Outcome
- rice N uptakee0
- Direction
- increasede0
- Value
- 12 to 14 kg ha −1e0
- Comparator
- tillage to 15 cme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased rice N uptake by 12 to 14 kg ha −1 , compared with tillage to 15 cm”
t0“Tillage Depth”
Claim · model-written summary
The increased nitrogen supply originated largely from the 15 to 30 cm layer.
- Taxon
- RiceOryza sativat0
- Outcome
- increased N supplye0
- Qualifier
- 15‐ to 30‐cm layere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increased N supply originating largely from the 15‐ to 30‐cm layer”
t0“Rice”
Claim · model-written summary
The authors attributed deep tillage benefits partly to removal of mechanical impediment to root proliferation.
- Taxon
- RiceOryza sativat0
- Organ / stage
- roote0
- Outcome
- beneficial effects of deep tillagee0
- Qualifier
- elimination of mechanical impedence to root proliferatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The beneficial effects of deep tillage were attributed to the elimination of mechanical impedence to root proliferation”
t0“Rice”
Claim · model-written summary
The authors attributed deep tillage benefits partly to lower subsoil N loss susceptibility.
- Taxon
- RiceOryza sativat0
- Outcome
- lower susceptibility of subsoil N to various loss mechanismse0
- Qualifier
- various loss mechanismse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower susceptibility of subsoil N to various loss mechanisms”
t0“Rice”
Claim · model-written summary
One 40 cm tillage every three seasons had no adverse effect on soil N fertility.
- Taxon
- RiceOryza sativat0
- Treatment
- 40‐cm‐deep tillage once in three seasonse0
- Outcome
- soil N fertilitye0
- Direction
- no adverse effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no adverse effect of practicing 40‐cm‐deep tillage once in three seasons on soil N fertility”
t0“Rice”
The same questions in other papers
tillage · nutrient: content · Oryza sativa (rice)Positive and negative results
97 papers in the same direction as this paper · 10 in the opposite direction
- positive
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- negative
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See all 108 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.