Interactions of nitrogen and phosphorus cycling promote P acquisition and explain synergistic plant-growth responses

Plant growth is often co-limited by nitrogen (N) and phosphorus (P). Plants might use one element to acquire another (i.e., trading N for P and P for N), which potentially explains synergistic growth responses to NP addition. We studied a 66-yr-old grassland experiment in South Africa that consists...

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Bibliographic Details
Published in:Ecology (Durham) Vol. 101; no. 5; pp. 1 - 14
Main Authors: Schleuss, Per Marten, Widdig, Meike, Heintz-Buschart, Anna, Kirkman, Kevin, Spohn, Marie
Format: Journal Article
Language:English
Published: United States John Wiley and Sons, Inc 01.05.2020
Ecological Society of America
Subjects:
Arbuscular mycorrhizas
Availability
ecological stoichiometry
Fertilization
fertilizer rates
Fungi
Grasslands
N and P co‐limitation
N and P trade‐offs
Net Primary Productivity
Nitrogen
Nitrogen - analysis
Nitrogen fixation
Nitrogenation
non‐symbiotic N2 fixation
Nutrients
operon
Phosphatase
phosphatase activity
Phosphorus
Plant communities
Plant Development
Plant growth
plant N and P uptake
Primary production
rRNA
Soil
Soil microorganisms
soil organic phosphorus
South Africa
vesicular arbuscular mycorrhizae
South Africa
phosphatase activity
N and P trade-offs
non-symbiotic N2 fixation
N and P co-limitation
plant N and P uptake
ecological stoichiometry
ISSN:0012-9658, 1939-9170, 1939-9170
Online Access:Get full text
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Summary:Plant growth is often co-limited by nitrogen (N) and phosphorus (P). Plants might use one element to acquire another (i.e., trading N for P and P for N), which potentially explains synergistic growth responses to NP addition. We studied a 66-yr-old grassland experiment in South Africa that consists of four levels of N addition with and without P addition. We investigated the response of aboveground net primary production (ANPP) to N and P addition over the last 66 yr. Further, we tested whether phosphatase activity and plant P uptake depend on N availability, and vice versa, whether non-symbiotic N2 fixation and plant N uptake depend on P availability. We expected that the interaction of both elements promote processes of nutrient acquisition and contribute to synergistic plant growth effects in response to NP addition. We found synergistic N and P co-limitation of ANPP for the period from 1951 to 2017 but the response to N and P addition diminished over time. In 2017, aboveground P stocks, relative rRNA operon abundance of arbuscular mycorrhizal fungi, and soil organic P storage increased with N fertilization rate when N was added with P compared to the treatment in which only N was added. Further, N addition increased phosphatase activity, which indicates that plants used N to acquire P from organic sources. In contrast, aboveground N stocks and non-symbiotic N2 fixation did not change significantly due to P addition. Taken together, our results indicate that trading N for P likely contributes to synergistic plant-growth response. Plants used added N to mobilize and take up P from organic sources, inducing stronger recycling of P and making the plant community less sensitive to external nutrient inputs. The latter could explain why indications of synergistic co-limitation diminished over time, which is usually overlooked in short-term nutrient addition experiments.
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ISSN:0012-9658
1939-9170
1939-9170
DOI:10.1002/ecy.3003