Abstract
Effective water and nitrogen (N) management strategies are critical for sustainable agricultural development. Lysimeter experiments with two deep percolation rates (low percolation and high percolation, i.e., LP and HP: 3 mm d−1 and 5 mm d−1) and five N application levels (N0~N4: 0, 60, 135, 210 and 285 kg N ha−1) were conducted to investigate the effects of controlled drainage on water productivity (WP) and N use efficiency (NUE) in water-saving irrigated paddy fields. The results demonstrated that NH4+-N and NO3−-N were the major components of total nitrogen (TN) in ponded water and leachate, accounting for more than 77.1% and 83.6% of TN, respectively. The risk of N leaching loss increased significantly under treatment of high percolation rates or high N application levels. High percolation loss required greater irrigation input, thus reducing WP. In addition, N uptake increased with increasing N application, but fertilization applied in excess of crop demand had a negative effect on grain yield. NUE was affected by the amount of N applied and increased with decreasing N levels. Water and N application levels had a significant effect on N uptake of rice, but their interaction on N uptake or NUE was not significant. For the LP and HP regimes, the highest N uptake and WP were obtained with N application levels of 285 kg ha−1 and 210 kg ha−1, respectively. Our overall results suggested that the combination of controlled drainage and water-saving irrigation was a feasible mitigation strategy to reduce N losses through subdrainage percolation and to provide more nutrients available for rice to improve NUE, thus reducing diffuse agricultural pollution. Long-term field trials are necessary to validate the lysimeter results.
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Claims 16
Claim · model-written summary
NH4+-N and NO3−-N were major components of ponded-water total nitrogen, accounting for more than 77.1%.
Not reportedTaxon
Verbatim
e0“NH4+-N and NO3−-N were the major components of total nitrogen (TN) in ponded water and leachate, accounting for more than 77.1% and 83.6% of TN, respectively.”
Claim · model-written summary
NH4+-N and NO3−-N accounted for 83.6% of total nitrogen in leachate.
Not reportedTaxon
Verbatim
e0“NH4+-N and NO3−-N were the major components of total nitrogen (TN) in ponded water and leachate, accounting for more than 77.1% and 83.6% of TN, respectively.”
Claim · model-written summary
High percolation significantly increased nitrogen leaching risk.
Not reportedTaxonComparator
Verbatim
e0“The risk of N leaching loss increased significantly under treatment of high percolation rates or high N application levels.”
Claim · model-written summary
High nitrogen application significantly increased nitrogen leaching risk.
Not reportedTaxonComparator
Verbatim
e0“The risk of N leaching loss increased significantly under treatment of high percolation rates or high N application levels.”
Claim · model-written summary
High percolation required greater irrigation input.
Not reportedTaxonComparator
Verbatim
e0“High percolation loss required greater irrigation input, thus reducing WP.”
Claim · model-written summary
High percolation reduced rice water productivity.
- Taxon
- Rice
Oryza sativat0 - Treatment
- High percolation losse0
- Outcome
- WPe0
- Direction
- reducinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High percolation loss required greater irrigation input, thus reducing WP.”
t0“Rice”
Claim · model-written summary
Rice nitrogen uptake increased with nitrogen application.
- Taxon
- RiceOryza sativat0
- Treatment
- increasing N applicatione0
- Outcome
- N uptakee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N uptake increased with increasing N application, but fertilization applied in excess of crop demand had a negative effect on grain yield.”
t0“Rice”
Claim · model-written summary
Fertilization exceeding rice demand negatively affected grain yield.
- Taxon
- RiceOryza sativat0
- Treatment
- fertilization applied in excess of crop demande0
- Outcome
- grain yielde0
- Direction
- negative effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fertilization applied in excess of crop demand had a negative effect on grain yield”
t0“Rice”
Claim · model-written summary
Rice nitrogen use efficiency increased as nitrogen application decreased.
- Taxon
- RiceOryza sativat0
- Treatment
- decreasing N levelse0
- Outcome
- NUEe0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NUE was affected by the amount of N applied and increased with decreasing N levels.”
t0“Rice”
Claim · model-written summary
Water application significantly affected rice nitrogen uptake, with direction unspecified.
- Taxon
- riceOryza sativae0
- Treatment
- Watere0
- Outcome
- N uptakee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water and N application levels had a significant effect on N uptake of rice, but their interaction on N uptake or NUE was not significant.”
Claim · model-written summary
Nitrogen application significantly affected rice nitrogen uptake.
- Taxon
- riceOryza sativae0
- Treatment
- N application levelse0
- Outcome
- N uptakee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water and N application levels had a significant effect on N uptake of rice, but their interaction on N uptake or NUE was not significant.”
Claim · model-written summary
The interaction of water and nitrogen application on rice nitrogen uptake and efficiency was not significant.
- Taxon
- riceOryza sativae0
- Treatment
- Water and N application levelse0
- Outcome
- N uptake or NUEe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water and N application levels had a significant effect on N uptake of rice, but their interaction on N uptake or NUE was not significant.”
Claim · model-written summary
For LP and HP regimes, highest rice nitrogen uptake occurred at 285 kg ha−1 nitrogen application.
- Taxon
- RiceOryza sativat0
- Treatment
- 285 kg ha−1e0
- Outcome
- N uptakee0
- Direction
- higheste0
- Qualifier
- LP and HP regimese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the LP and HP regimes, the highest N uptake and WP were obtained with N application levels of 285 kg ha−1 and 210 kg ha−1, respectively.”
t0“Rice”
Claim · model-written summary
For LP and HP regimes, highest rice water productivity occurred at 210 kg ha−1 nitrogen application.
- Taxon
- RiceOryza sativat0
- Treatment
- 210 kg ha−1e0
- Outcome
- WPe0
- Direction
- higheste0
- Qualifier
- LP and HP regimese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the LP and HP regimes, the highest N uptake and WP were obtained with N application levels of 285 kg ha−1 and 210 kg ha−1, respectively.”
t0“Rice”
Claim · model-written summary
The authors recommend controlled drainage combined with water-saving irrigation to reduce nitrogen losses and improve rice nitrogen availability and efficiency.
- Taxon
- riceOryza sativae0
- Outcome
- combination of controlled drainage and water-saving irrigatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Our overall results suggested that the combination of controlled drainage and water-saving irrigation was a feasible mitigation strategy to reduce N losses through subdrainage percolation and to provide more nutrients available for rice to improve NUE, thus reducing diffuse agricultural pollution.”
Claim · model-written summary
Long-term field trials are necessary to validate the rice lysimeter results.
- Taxon
- RiceOryza sativat0
- Outcome
- Long-term field trialse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Long-term field trials are necessary to validate the lysimeter results.”
t0“Rice”
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