Abstract
Improving nitrogen use efficiency (NUE) and decreasing N loss are critical to sustainable agriculture. The objective of this research was to investigate the effect of various fertilization regimes on yield, NUE, N agronomic efficiency (NAE) and N loss in long-term (16- or 24-yr) experiments carried out at three rice-wheat rotation sites (Chongqing, Suining and Wuchang) in subtropical China. Three treatments were examined: sole chemical N, N+phosphorus (NP), and NP+potassium (NPK) fertilizations. Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone, 1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP. Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%) and Wuchang (11.8%), but not at Suining, China. No changes in NUE were observed in rice between NP and NPK at all three sites. The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing, while NAE was similar for NP and NPK at Suining and Wuchang. We estimated that an uptake increase of 1.0 kg N ha−1 would increase 40 kg rice and 30 kg wheat ha−1. Nitrogen loss/input ratios were ∼60, ∼40 or ∼30% under N, NP or NPK at three sites, indicating significant decrease of N loss by P or PK additions. We attribute part of the increase in NUE soil N accumulation which significantly increased by 25–55 kg ha−1 yr−1 under NPK at three sites, whereas by 35 kg ha−1 yr−1 under NP at Chongqing only. This paper illustrates that apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China.
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Claims 18
Claim · model-written summary
NP increased rice yield by 9.3–81.6% relative to N alone.
- Taxon
- rice
Oryza sativae0 - Treatment
- NPe0
- Outcome
- Grain yieldse0
- Direction
- increasede0
- Value
- 9.3–81.6%e0
- Comparator
- N alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone”
Claim · model-written summary
NP increased wheat yield by 54.5–93.8% relative to N alone.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- NPe0
- Outcome
- Grain yieldse0
- Direction
- increasede0
- Value
- 54.5–93.8%e0
- Comparator
- N alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone”
Claim · model-written summary
NPK raised rice yield by 1.7–9.8% relative to NP.
- Taxon
- riceOryza sativae0
- Treatment
- NPKe0
- Outcome
- Grain yieldse1
- Direction
- higherinferrede0
- Value
- 1.7–9.8%e0
- Comparator
- NPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP”
e1“Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone”
Claim · model-written summary
NPK raised wheat yield by 0–17.6% relative to NP.
- Taxon
- wheatTriticum aestivume0
- Treatment
- NPKe0
- Outcome
- Grain yieldse1
- Direction
- higherinferrede0
- Value
- 0–17.6%e0
- Comparator
- NPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP”
e1“Grain yields at three sites were significantly increased by 9.3–81.6% (rice) and 54.5–93.8% (wheat) under NP compared with N alone”
Claim · model-written summary
NPK increased wheat NUE by 9.3% relative to NP at Chongqing.
- Taxon
- wheatTriticum aestivume0
- Treatment
- NPKe1
- Outcome
- NUEe0
- Direction
- increasede0
- Value
- 9.3%e0
- Comparator
- NPe0
- Setting
- Chongqinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%)”
e1“1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP”
Claim · model-written summary
NPK increased wheat NUE by 11.8% relative to NP at Wuchang.
- Taxon
- wheatTriticum aestivume0
- Treatment
- NPKe1
- Outcome
- NUEe0
- Direction
- increasede0
- Value
- 11.8%e0
- Comparator
- NPe0
- Setting
- Wuchange0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%) and Wuchang (11.8%)”
e1“1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP”
Claim · model-written summary
Wheat NUE did not significantly increase with NPK at Suining.
- Taxon
- wheatTriticum aestivume1
- Treatment
- NPKe2
- Outcome
- NUEe1
- Direction
- no_changeinferrede0
- Comparator
- NPe1
- Setting
- Suining, Chinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not at Suining, China”
e1“Compared to NP, NUE significantly increased for wheat at Chongqing (9.3%)”
e2“1.7–9.8% (rice) and 0–17.6% (wheat) with NPK compared with NP”
Claim · model-written summary
Rice NUE did not change between NP and NPK at the three sites.
- Taxon
- riceOryza sativae0
- Treatment
- NPKe0
- Outcome
- NUEe0
- Direction
- No changese0
- Qualifier
- all three sitese0
- Comparator
- NPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No changes in NUE were observed in rice between NP and NPK at all three sites”
Claim · model-written summary
Rotation NAE was 3.3 kg kg−1 higher under NPK than NP at Chongqing.
Verbatim
e0“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
Rotation NAE was similar under NPK and NP at Suining and Wuchang.
Verbatim
e0“NAE was similar for NP and NPK at Suining and Wuchang”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
Estimated additional N uptake of 1.0 kg N ha−1 corresponded to 40 kg additional rice yield.
- Taxon
- riceOryza sativae0
- Compound
- Ne0
- Outcome
- ricee0
- Direction
- increasee0
- Value
- 40 kge0
- Qualifier
- 1.0 kg N ha−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an uptake increase of 1.0 kg N ha−1 would increase 40 kg rice and 30 kg wheat ha−1”
Claim · model-written summary
Estimated additional N uptake of 1.0 kg N ha−1 corresponded to 30 kg additional wheat yield.
- Taxon
- wheatTriticum aestivume0
- Compound
- Ne0
- Outcome
- wheate0
- Direction
- increasee0
- Value
- 30 kg wheat ha−1e0
- Qualifier
- 1.0 kg N ha−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an uptake increase of 1.0 kg N ha−1 would increase 40 kg rice and 30 kg wheat ha−1”
Claim · model-written summary
N loss to input ratios were approximately 60% under N.
Verbatim
e0“Nitrogen loss/input ratios were ∼60, ∼40 or ∼30% under N, NP or NPK at three sites”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
N loss to input ratios were approximately 40% under NP.
Verbatim
e0“Nitrogen loss/input ratios were ∼60, ∼40 or ∼30% under N, NP or NPK at three sites”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
N loss to input ratios were approximately 30% under NPK.
Verbatim
e0“Nitrogen loss/input ratios were ∼60, ∼40 or ∼30% under N, NP or NPK at three sites”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
NPK increased soil N accumulation by 25–55 kg ha−1 yr−1 across three sites.
- Taxon
- rice-wheate1
- Treatment
- NPKe0
- Outcome
- soil N accumulatione0
- Direction
- increasede0
- Value
- 25–55 kg ha−1 yr−1e0
Not reportedComparator
Verbatim
e0“soil N accumulation which significantly increased by 25–55 kg ha−1 yr−1 under NPK at three sites”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
Claim · model-written summary
NP increased soil N accumulation by 35 kg ha−1 yr−1 at Chongqing only.
- Taxon
- rice-wheate1
- Treatment
- NPe0
- Outcome
- soil N accumulatione2
- Direction
- increaseinferrede0
- Value
- 35 kg ha−1 yr−1e0
- Setting
- Chongqinge0
Not reportedComparator
Verbatim
e0“whereas by 35 kg ha−1 yr−1 under NP at Chongqing only”
e1“The rice-wheat rotation's NAE was 3.3 kg kg−1 higher under NPK than under NP at Chongqing”
e2“soil N accumulation which significantly increased by 25–55 kg ha−1 yr−1 under NPK at three sites”
Claim · model-written summary
The authors recommend P and K for wheat and less K for rice to improve NUE and reduce N loss.
- Taxon
- wheatTriticum aestivume0
- Outcome
- apply P and K to wheate0
- Setting
- Chinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“apply P and K to wheat, and reduce K application to rice is an effective nutrient management strategy for both the NUE improvement and N losses reduction in China”
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