Abstract
Abstract In pursuit of maximum grain yield farmers in the North China Plain usually apply excessive N fertilizer, resulting in wasted resources and environmental pollution. To assess the economic and environmental performances of different nitrogen rates will be conductive to sustain cleaner crop production. An 8-year field experiment was carried out with four treatments, N0 (0 kg ha −1 for winter wheat and summer maize), N1 (168 kg ha −1 for winter wheat and 129 kg ha −1 for summer maize), N2 (240 kg ha −1 for winter wheat and 185 kg ha −1 for summer maize) and N3 (300 kg ha −1 for winter wheat and summer maize), on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China. The crop production, soil physical-chemical parameters, and greenhouse gas emission are measured and the economic and environmental performances are assessed. The optimal nitrogen rate obtained the highest grain yield of summer maize in 4 of 8 year and was equivalent to conventional N rate in the other years. The nitrogen partial factor productivity and agronomic efficiency of optimal nitrogen rate was 63% and 58% higher than that of conventional nitrogen rate. The optimal nitrogen rate effectively decreased soil bulk density and increased weight percentage of water-stable aggregate and activities of urease and invertase compared to conventional nitrogen rate, which improved soil productivity. The fertilizer nitrogen loss and global warming potential of optimal nitrogen rate reduced by 76% and 35% compared to conventional nitrogen rate. The annual greenhouse gas intensity of optimal nitrogen rate decreased by 14–35% compared to others. The net ecosystem economic budget under optimal nitrogen rate is 252–604 $ ha −1 yr. −1 higher than other addition levels. The optimal nitrogen rate produces more grains and obtains higher economic and environmental benefits.
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Claims 13
Claim · model-written summary
The optimal nitrogen rate gave the highest summer maize grain yield in 4 of 8 years.
- Treatment
- optimal nitrogen ratee1
- Outcome
- grain yielde1
- Direction
- higheste1
- Setting
- Dawenkou research fielde2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The optimal nitrogen rate obtained the highest grain yield of summer maize in 4 of 8 year”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
Claim · model-written summary
Grain yield under the optimal nitrogen rate was equivalent to the conventional N rate in the other years.
- Treatment
- optimal nitrogen ratee1
- Outcome
- grain yielde1
- Direction
- equivalente3
- Comparator
- conventional N ratee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The optimal nitrogen rate obtained the highest grain yield of summer maize in 4 of 8 year”
e3“was equivalent to conventional N rate in the other years”
Claim · model-written summary
The optimal nitrogen rate raised nitrogen partial factor productivity by 63% over the conventional N rate.
- Taxon
- winter wheat and summer maize
Triticum aestivum
Zea mayse0 - Treatment
- optimal nitrogen ratee4
- Outcome
- nitrogen partial factor productivitye4
- Direction
- highere4
- Value
- 63%e4
- Comparator
- conventional nitrogen ratee4
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e4“The nitrogen partial factor productivity and agronomic efficiency of optimal nitrogen rate was 63% and 58% higher than that of conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate raised agronomic efficiency by 58% over the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee4
- Outcome
- agronomic efficiencye4
- Direction
- highere4
- Value
- 58%e4
- Comparator
- conventional nitrogen ratee4
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e4“The nitrogen partial factor productivity and agronomic efficiency of optimal nitrogen rate was 63% and 58% higher than that of conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate effectively decreased soil bulk density compared with the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee5
- Outcome
- soil bulk densitye5
- Direction
- decreasede5
- Comparator
- conventional nitrogen ratee5
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e5“The optimal nitrogen rate effectively decreased soil bulk density and increased weight percentage of water-stable aggregate and activities of urease and invertase compared to conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate increased the weight percentage of water-stable aggregate compared with the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee5
- Outcome
- weight percentage of water-stable aggregatee5
- Direction
- increasede5
- Comparator
- conventional nitrogen ratee5
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e5“The optimal nitrogen rate effectively decreased soil bulk density and increased weight percentage of water-stable aggregate and activities of urease and invertase compared to conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate increased urease and invertase activities compared with the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee5
- Outcome
- activities of urease and invertasee5
- Direction
- increasede5
- Comparator
- conventional nitrogen ratee5
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e5“The optimal nitrogen rate effectively decreased soil bulk density and increased weight percentage of water-stable aggregate and activities of urease and invertase compared to conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate reduced fertilizer nitrogen loss by 76% compared with the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee6
- Outcome
- fertilizer nitrogen losse6
- Direction
- reducede6
- Value
- 76%e6
- Comparator
- conventional nitrogen ratee6
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e6“The fertilizer nitrogen loss and global warming potential of optimal nitrogen rate reduced by 76% and 35% compared to conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate reduced global warming potential by 35% compared with the conventional N rate.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee6
- Outcome
- global warming potentiale6
- Direction
- reducede6
- Value
- 35%e6
- Comparator
- conventional nitrogen ratee6
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e6“The fertilizer nitrogen loss and global warming potential of optimal nitrogen rate reduced by 76% and 35% compared to conventional nitrogen rate”
Claim · model-written summary
The optimal nitrogen rate decreased annual greenhouse gas intensity by 14–35% compared with the other N rates.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee7
- Outcome
- annual greenhouse gas intensitye7
- Direction
- decreasede7
- Value
- 14–35%e7
- Comparator
- otherse7
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e7“The annual greenhouse gas intensity of optimal nitrogen rate decreased by 14–35% compared to others”
Claim · model-written summary
The net ecosystem economic budget under the optimal nitrogen rate was 252–604 $ ha −1 yr. −1 higher than under other addition levels.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee5
- Outcome
- net ecosystem economic budgete5
- Direction
- highere5
- Value
- 252–604 $ ha −1 yr. −1e5
- Comparator
- other addition levelse5
- Setting
- Dawenkou research fielde2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e5“The net ecosystem economic budget under optimal nitrogen rate is 252–604 $ ha −1 yr. −1 higher than other addition levels”
Claim · model-written summary
The optimal nitrogen rate produced more grains.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee6
- Outcome
- grainse6
- Direction
- moree6
- Setting
- Dawenkou research fielde2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e6“The optimal nitrogen rate produces more grains and obtains higher economic and environmental benefits”
Claim · model-written summary
The optimal nitrogen rate obtained higher economic and environmental benefits.
- Taxon
- winter wheat and summer maizeTriticum aestivumZea mayse0
- Treatment
- optimal nitrogen ratee6
- Outcome
- economic and environmental benefitse6
- Direction
- highere6
- Setting
- Dawenkou research fielde2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N3 (300 kg ha −1 for winter wheat and summer maize)”
e2“on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China”
e6“The optimal nitrogen rate produces more grains and obtains higher economic and environmental benefits”
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See all 194 papers →8 of 10 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
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