Abstract
Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N), and has been shown to limit aboveground production in some contexts. However, the role of N and phosphorus (P) availability in mediating K limitation in terrestrial production remains poorly understood; and it is unknown whether K also limits belowground carbon (C) stocks, which contain at least three times more C than those aboveground stocks. By synthesizing 779 global paired observations (528, 125, and 126 for aboveground productivity, root biomass, and soil organic C [SOC], respectively), we found that K addition significantly increased aboveground production and SOC by 8% and 5%, respectively, but did not significantly affect root biomass (+9%). Moreover, enhanced N and/or P availability (through N and P addition) did not further amplify the positive effect of K on aboveground productivity. In other words, K had a positive effect on aboveground productivity only when N and/or P were limiting, indicating that K could somehow substitute for N or P when they were limiting. Climate variables mostly explained the variations in K effects; specifically, stronger positive responses of aboveground productivity and SOC to K were found in regions with high mean annual temperature and wetness. Our results suggest that K addition enhances C sequestration by increasing both aboveground productivity and SOC, contributing to climate mitigation, but the positive effects of K on terrestrial C stocks are not further amplified when N and P limitations are alleviated.
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Claims 10
Claim · model-written summary
K addition significantly increased aboveground production by 8%.
- Taxon
- plantsViridiplantaee0
- Treatment
- K additione1
- Outcome
- aboveground productione1
- Direction
- increasede1
- Value
- 8%e1
Not reportedComparator
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e1“K addition significantly increased aboveground production and SOC by 8% and 5%, respectively, but did not significantly affect root biomass (+9%)”
Claim · model-written summary
K addition significantly increased soil organic C (SOC) by 5%.
Not reportedComparator
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e1“K addition significantly increased aboveground production and SOC by 8% and 5%, respectively, but did not significantly affect root biomass (+9%)”
Claim · model-written summary
K addition did not significantly affect root biomass (+9%).
- Taxon
- plantsViridiplantaee0
- Treatment
- K additione1
- Outcome
- root biomasse1
- Direction
- did not significantly affecte1
- Value
- +9%e1
Not reportedComparator
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e1“K addition significantly increased aboveground production and SOC by 8% and 5%, respectively, but did not significantly affect root biomass (+9%)”
Claim · model-written summary
Enhanced N and/or P availability did not further amplify the positive effect of K on aboveground productivity.
- Taxon
- plantsViridiplantaee0
- Treatment
- N and P additione2
- Outcome
- aboveground productivitye2
- Direction
- did not further amplifye2
Not reportedComparator
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e2“Moreover, enhanced N and/or P availability (through N and P addition) did not further amplify the positive effect of K on aboveground productivity”
Claim · model-written summary
K had a positive effect on aboveground productivity only when N and/or P were limiting.
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e3“In other words, K had a positive effect on aboveground productivity only when N and/or P were limiting, indicating that K could somehow substitute for N or P when they were limiting”
Claim · model-written summary
K could substitute for N or P when they are limiting.
- Taxon
- plantsViridiplantaee0
- Compound
- Ke3
- Outcome
- substitute for N or Pe3
- Qualifier
- when they were limitinge3
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e3“In other words, K had a positive effect on aboveground productivity only when N and/or P were limiting, indicating that K could somehow substitute for N or P when they were limiting”
Claim · model-written summary
Climate variables mostly explained the variations in K effects.
- Taxon
- plantsViridiplantaee0
- Treatment
- Climate variablese4
- Outcome
- variations in K effectse4
Not reportedDirection
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e4“Climate variables mostly explained the variations in K effects”
Claim · model-written summary
Stronger positive responses of aboveground productivity and SOC to K were found in regions with high mean annual temperature and wetness.
- Taxon
- plantsViridiplantaee0
- Outcome
- aboveground productivity and SOCe5
- Direction
- stronger positive responsese5
- Setting
- regions with high mean annual temperature and wetnesse5
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e5“stronger positive responses of aboveground productivity and SOC to K were found in regions with high mean annual temperature and wetness”
Claim · model-written summary
K addition enhances C sequestration by increasing aboveground productivity and SOC, contributing to climate mitigation.
- Taxon
- plantsViridiplantaee0
- Treatment
- K additione6
- Outcome
- C sequestratione6
- Direction
- enhancese6
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e6“Our results suggest that K addition enhances C sequestration by increasing both aboveground productivity and SOC, contributing to climate mitigation”
Claim · model-written summary
The positive effects of K on terrestrial C stocks are not further amplified when N and P limitations are alleviated.
- Taxon
- plantsViridiplantaee0
- Treatment
- N and P limitations are alleviatede7
- Outcome
- terrestrial C stockse7
- Direction
- not further amplifiede7
Verbatim
e0“Potassium (K) is the second most abundant nutrient element in plants after nitrogen (N)”
e7“but the positive effects of K on terrestrial C stocks are not further amplified when N and P limitations are alleviated”
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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.