Plant and microbial uptake of nitrogen and phosphorus affected by drought using 15N and 32P tracers

Dijkstra, Feike A.; He, Mingzhu; Johansen, Mathew P.; Harrison, Jennifer; Keitel, Claudia

doi:10.1016/j.soilbio.2014.12.021

Cited by 93 publications

(54 citation statements)

References 52 publications

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“…Plants and microbes often compete for key nutrients in nutrient poor systems, however microbes can also facilitate plant nutrient uptake by boosting N and P mineralisation in the rhizosphere (Marschner et al, 2011;Dijkstra et al, 2015). The NP colimitation effect on nutrient cycling reported here has not been widely reported elsewhere.…”

Section: Impact Of N Additionmentioning

confidence: 71%

Nitrogen and phosphorus co-limitation and grazing moderate nitrogen impacts on plant growth and nutrient cycling in sand dune grassland

Ford

Roberts

Jones

2016

Science of The Total Environment

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Atmospheric nitrogen (N) deposition alters plant biodiversity and ecosystem function in grasslands worldwide. This study examines the impact of 6 years of nutrient addition and grazing management on a sand dune grassland. Results indicate that co-limitation of N and phosphorus (P) moderates the impact of realistic rates of N addition (7.5, 15 kg N ha −1 year −1 ). Combined NP addition (15 kg N + 10 kg P ha −1 year −1 ) was the only nutrient treatment to differ significantly from the control, with greater above-ground biomass (mainly moss), and enhanced N and P mineralisation rates. Grazing management altered plant functional group composition, reduced above-ground biomass and meso-faunal feeding rates, and decoupled N and P mineralisation. There were no synergistic effects of grazing and N treatment. Although NP co-limitation apparently prevents adverse impacts of N deposition above the critical load, excess N is likely to be stored in moss biomass and soil, with unknown future consequences.Capsule: This study shows that at realistic levels of N addition, NP co-limitation in a dune grassland appears to prevent adverse impacts of N on plant growth and nutrient cycling.

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Section: Impact Of N Additionmentioning

confidence: 71%

Nitrogen and phosphorus co-limitation and grazing moderate nitrogen impacts on plant growth and nutrient cycling in sand dune grassland

Ford

Roberts

Jones

2016

Science of The Total Environment

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“…Nitrification declines under low osmotic potentials (Stark & Firestone, ), and in drying soils, a larger fraction of nitrified N can escape as NO (Figure b; Davidson et al, ; Homyak et al, ; Homyak et al, ), which, together, imply that NO 3 − production could have declined. Similarly, the processes consuming NO 3 − probably also declined; plant NO 3 − uptake declines under drought stress (Dijkstra et al, ; Meng et al, ) as do N 2 O emissions (Figure ). Thus, NO 3 − concentrations may not have changed because reductions in production and consumption of NO 3 − offset one another (Figure b).…”

Section: Discussionmentioning

confidence: 96%

Effects of Drought Manipulation on Soil Nitrogen Cycling: A Meta‐Analysis

et al. 2017

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Many regions on Earth are expected to become drier with climate change, which may impact nitrogen (N) cycling rates and availability. We used a meta‐analytical approach on the results of field experiments that reduced precipitation and measured N supply (i.e., indices of N mineralization), soil microbial biomass, inorganic N pools (ammonium (NH4+) and nitrate (NO3−)), and nitrous oxide (N2O) emissions. We hypothesized that N supply and N2O emissions would be relatively insensitive to precipitation reduction and that reducing precipitation would increase extractable NH4+ and NO3− concentrations because microbial processes continue, whereas plant N uptake diminishes with drought. In support of this hypothesis, extractable NH4+ increased by 25% overall with precipitation reduction; NH4+ also increased significantly with increasing magnitude of precipitation reduction. In contrast, N supply and extractable NO3− did not change and N2O emissions decreased with reduced precipitation. Across studies microbial biomass appeared unchanged, yet from the diversity of studies, it was clear that proportionally smaller precipitation reductions increased microbial biomass, whereas larger proportional reductions in rainfall reduced microbial biomass; there was a positive intercept (P = 0.005) and a significant negative slope (P = 0.0002) for the regression of microbial biomass versus % precipitation reduction (LnR = −0.009 × (% precipitation reduction) + 0.4021). Our analyses imply that relative to other N variables, N supply is less sensitive to reduced precipitation, whereas processes producing N2O decline. Drought intensity and duration, through sustained N supply, may control how much N becomes vulnerable to loss via hydrologic and gaseous pathways upon rewetting dry soils.

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“…Indeed, the decrease in soil moisture can strongly reduce N mobility in the soil due to lower diffusion and mass flow (Lambers, Chapin & Pons 2008). As a consequence, this may considerably limit root access to N pools and reduce plant N uptake (Dijkstra et al 2015), especially for species that strongly depend on this resource (i.e., dominant species). We therefore suggest that the increase in soil N availability observed in our experiment was primarily due to reduced N uptake of the drought-sensitive dominant species.…”

Section: Discussionmentioning

confidence: 99%

Stoichiometric N:P flexibility and mycorrhizal symbiosis favour plant resistance against drought

2017

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Summary Drought induces changes in the nitrogen (N) and phosphorus (P) cycle but most plant species have limited flexibility to take up nutrients under such variable or unbalanced N and P availability. Both the degree of flexibility in plant N:P ratio and of root symbiosis with arbuscular mycorrhizal fungi might control plant resistance to drought‐induced changes in nutrient availability, but this has not been directly tested. Here, we examined the role of plant N:P stoichiometric status and mycorrhizal symbiosis in the drought‐resistance of dominant and subordinate species in a semi‐natural grassland. We reduced water availability using rainout shelters (control vs. drought) and measured how plant biomass responded for the dominant and subordinate species. We then selected a dominant (Paspalum dilatatum) and a subordinate species (Cynodon dactylon), for which we investigated the N:P stoichiometric status, mycorrhizal root colonization and water‐use efficiency. The biomass of all dominant plant species, but not subordinate species, decreased under drought. Drought increased soil available nitrogen, and thus increased soil N:P ratio, due to decreasing plant N uptake. The dominant P. dilatatum showed a high degree of plant N:P homeostasis and a considerable reduction in biomass under drought. At the opposite, the more flexible subordinate species C. dactylon increased its N uptake and water‐use efficiency, apparently due to stronger symbiosis with mycorrhizae, and maintained its biomass. Synthesis. We conclude that the maintenance of N:P homeostasis in dominant species, possibly because of a large root nutrient foraging capacity, becomes inefficient when water stress limits N mobility in the soil. By contrast, we demonstrate that higher stoichiometric N:P flexibility coupled with stronger mutualistic association with mycorrhizae allow subordinate species to better withstand drought perturbations. Using a stoichiometric approach in a field experiment, our study provides for the first time clear and novel understandings of the mechanisms involved in drought‐resistance within the plant‐mycorrhizae‐soil system.

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Plant and microbial uptake of nitrogen and phosphorus affected by drought using 15N and 32P tracers

Cited by 93 publications

References 52 publications

Nitrogen and phosphorus co-limitation and grazing moderate nitrogen impacts on plant growth and nutrient cycling in sand dune grassland

Nitrogen and phosphorus co-limitation and grazing moderate nitrogen impacts on plant growth and nutrient cycling in sand dune grassland

Effects of Drought Manipulation on Soil Nitrogen Cycling: A Meta‐Analysis

Stoichiometric N:P flexibility and mycorrhizal symbiosis favour plant resistance against drought

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