Dataset Information

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a ¹⁵N-tracer approach.

ABSTRACT:

Purpose

Nitrogen (N) transfer from white clover (Trifolium repens cv.) to ryegrass (Lolium perenne cv.) has the potential to meet ryegrass N requirements. This study aimed to quantify N transfer in a mixed pasture and investigate the influence of the microbial community and land management on N transfer.

Methods

Split root ¹⁵N-labelling of clover quantified N transfer to ryegrass via exudation, microbial assimilation, decomposition, defoliation and soil biota. Incorporation into the microbial protein pool was determined using compound-specific ¹⁵N-stable isotope probing approaches.

Results

N transfer to ryegrass and soil microbial protein in the model system was relatively small, with one-third arising from root exudation. N transfer to ryegrass increased with no microbial competition but soil microbes also increased N transfer via shoot decomposition. Addition of mycorrhizal fungi did not alter N transfer, due to the source-sink nature of this pathway, whilst weevil grazing on roots decreased microbial N transfer. N transfer was bidirectional, and comparable on a short-term scale.

Conclusions

N transfer was low in a model young pasture established from soil from a permanent grassland with long-term N fertilisation. Root exudation and decomposition were major N transfer pathways. N transfer was influenced by soil biota (weevils, mycorrhizae) and land management (e.g. grazing). Previous land management and the role of the microbial community in N transfer must be considered when determining the potential for N transfer to ryegrass.

Supplementary information

The online version contains supplementary material available at 10.1007/s11104-022-05585-0.

SUBMITTER: Reay MK

PROVIDER: S-EPMC9705487 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a <sup>15</sup>N-tracer approach.

Reay Michaela K MK Pears Katrina A KA Kuhl Alison A Evershed Richard P RP Murray Phillip J PJ Cardenas Laura M LM Dungait Jennifer A J JAJ Bull Ian D ID

Plant and soil 20220728 1-2

<h4>Purpose</h4>Nitrogen (N) transfer from white clover (<i>Trifolium repens</i> cv.) to ryegrass (<i>Lolium perenne</i> cv.) has the potential to meet ryegrass N requirements. This study aimed to quantify N transfer in a mixed pasture and investigate the influence of the microbial community and land management on N transfer.<h4>Methods</h4>Split root <sup>15</sup>N-labelling of clover quantified N transfer to ryegrass via exudation, microbial assimilation, decomposition, defoliation and soil bi ...[more]

PMID: 36466744

Similar Datasets

Project description:The 15N isotope pool dilution (IPD) technique is the only available method for measuring gross ammonium (NH4 +) production and consumption rates. Rapid consumption of the added 15N-NH4 + tracer is commonly observed, but the processes responsible for this consumption are not well understood. The primary objectives of this study were to determine the relative roles of biotic and abiotic processes in 15N-NH4 + sconsumption and to investigate the validity of one of the main assumptions of IPD experiments, i.e., that no reflux of the consumed 15N tracer occurs during the course of the experiments. We added a 15N-NH4 + tracer to live and sterile (autoclaved) soil using mineral topsoil from a beech forest and a grassland in Austria that differed in NH4 + concentrations and NH4 + consumption kinetics. We quantified both biotic tracer consumption (i.e. changes in the concentrations and 15N enrichments of NH4 +, dissolved organic N (DON), NO3 - and the microbial N pool) and abiotic tracer consumption (i.e., fixation by clay and/or humic substances). We achieved full recovery of the 15N tracer in both soils over the course of the 48 h incubation. For the forest soil, we found no rapid consumption of the 15N tracer, and the majority of tracer (78%) remained unconsumed at the end of the incubation period. In contrast, the grassland soil showed rapid 15N-NH4 + consumption immediately after tracer addition, which was largely due to both abiotic fixation (24%) and biotic processes, largely uptake by soil microbes (10%) and nitrification (13%). We found no evidence for reflux of 15N-NH4 + over the 48 h incubation period in either soil. Our study therefore shows that 15N tracer reflux during IPD experiments is negligible for incubation times of up to 48 h, even when rapid NH4 + consumption occurs. Such experiments are thus robust to the assumption that immobilized labeled N is not re-mobilized during the experimental period and does not impact calculations of gross N mineralization.

Project description:China consumes 35% of the world's fertilizer every year; however, most of the nitrogen fertilizers, which are essential for rice cultivation, are not used effectively. In this study, factors affecting the nitrogen leaching loss rate were studied in typical soil and rice varieties in South China. The effects of various irrigation measures on rice growth and nitrogen leaching loss were investigated by conducting experiments with eight groups. These groups included traditional irrigation (TI) and shallow wet irrigation (SWI). The TI is a common irrigation method for farmers in South China, maintaining a water layer of 5-8 cm depth. For SWI, after establishing a shallow water layer usually maintaining at 1-2 cm, paddy is irrigated when the field water level falls to a certain depth, then this process is then repeat as necessary. The nitrogen distribution characteristics were determined using 15N isotope tracing. In addition, the effects of nitrification, denitrification, and microbial composition on soil nitrogen transformation at different depths were studied by microbial functional gene quantification and high-throughput sequencing. The results revealed that in the SWI groups, the total nitrogen leaching loss rate reduced by 0.3-0.8% and the nitrogen use efficiency (NUE) increased by 2.18-4.43% compared with those in the TI groups. After the 15N-labeled nitrogen fertilizer was applied, the main pathways of nitrogen were found to be related to plant absorption and nitrogen residues. Furthermore, paddy soil ammonia-oxidizing archaea were more effective than ammonia-oxidizing bacteria for soil ammonia oxidation by SWI groups. The SWI measures increased the relative abundance of Firmicutes in paddy soil, enhancing the ability of rice to fix nitrogen to produce ammonium nitrogen, thus reducing the dependence of rice on chemical fertilizers. Moreover, SWI enhanced the relative abundance of nirS and nosZ genes within surface soil bacteria, thereby promoting denitrification in the surface soil of paddy fields. SWI also promoted ammonia oxidation and denitrification by increasing the abundance and activity of Proteobacteria, Nitrospirae, and Bacteroidetes. Collectively, SWI effectively reduced the nitrogen leaching loss rate and increase NUE.

Dataset Information

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a ¹⁵N-tracer approach.

Purpose

Methods

Results

Conclusions

Supplementary information

Publications

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a <sup>15</sup>N-tracer approach.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a 15N-tracer approach.

Purpose

Methods

Results

Conclusions

Supplementary information

Publications

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a &lt;sup&gt;15&lt;/sup&gt;N-tracer approach.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a ¹⁵N-tracer approach.

Mechanisms of nitrogen transfer in a model clover-ryegrass pasture: a <sup>15</sup>N-tracer approach.