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Above- and belowground nitrogen distribution of a red clover-perennial ryegrass sward along a soil nutrient availability gradient established by organic and conventional cropping systems

Hammelehle, Andreas; Oberson, Astrid; Lüscher, Andreas; Mäder, Paul and Mayer, Jochen (2018) Above- and belowground nitrogen distribution of a red clover-perennial ryegrass sward along a soil nutrient availability gradient established by organic and conventional cropping systems. Plant and Soil, 425 (1-2), pp. 507-525.

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Online at: https://link.springer.com/article/10.1007%2Fs11104-018-3559-z

Summary

Aims
Belowground legume nitrogen (N) composed of roots and rhizodeposition is an important N input to soils, but published data of belowground N vary broadly, probably due to extrapolation from short-term experiments and dissimilar growing conditions. We quantified belowground N inputs of red clover (Trifolium pratense L.) during two consecutive years in a clover-grass sward along a soil nutrient availability gradient.
Methods
We established a red clover-perennial ryegrass (Lolium perenne L.) model sward in microplots located in field plots of the DOK experiment, which has a 33-year history of organic and conventional cropping, resulting in a soil nutrient availability gradient. Four treatments were examined: the zero fertilisation control, bio-organic with half and full dose manure application, and the conventional system with mineral fertilisation at full dose. We studied the development of clover aboveground and belowground N using multiple pulse 15N urea leaf labelling.
Results
Belowground clover N increased over time and with rising nutrient availability and was proportional to aboveground clover N at all times. Belowground clover N amounted to 40% of aboveground clover N during two consecutive years, irrespective of the nutrient availability status. Belowground clover N development was initially dominated by fast root growth, followed by enhanced root turnover during the second year. Potassium availability limited clover growth and total N accumulation in treatments with low nutrient availability.
Conclusions
Belowground red clover N inputs could be estimated from aboveground N by a constant factor of 0.4, regardless of the nutrient availability and cultivation time. Root turnover led to a distinct absolute increase of N rhizodeposition over time. Hence, N rhizodeposition, with an 80% share of belowground N, was the predominant N pool at the end of the second year.


EPrint Type:Journal paper
Keywords:Rhizodeposition, 15N leaf labelling, Cropping systems, Belowground to aboveground N ratio, Nutrient availability, system comparison, soil quality
Subjects: Soil > Soil quality
Crop husbandry > Composting and manuring
Research affiliation: Switzerland > FiBL - Research Institute of Organic Agriculture Switzerland > Soil Sciences
Switzerland > Agroscope
ISSN:Print: 0032-079X, Online: 1573-5036
DOI:https://doi.org/10.1007/s11104-018-3559-z
Deposited By: Mäder, Paul
ID Code:34924
Deposited On:13 Mar 2019 14:34
Last Modified:14 Mar 2019 13:37
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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