Relationships between soil thermal units, nitrogen mineralization and dry matter production in pastures |
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Authors: | T. J. Clough S. C. Jarvis D. J. Hatch |
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Affiliation: | AgResearch, Ruakura Agricultural Research Cetre, Hamilton, New Zealand.;Institute of Grassland and Environmental Research, North Wyke, Okehampton, Devon, EX20 2SB, UK. |
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Abstract: | Abstract. Nitrogen (N) is of enviromental concern if it leaches or is released as nitrous oxide (N2O,). In order to utilize N efficiently in grazed pasture systems, the fluxes of N from various sources need to be quantified. One flux is N mineralization from organic sources. Previous work has examined incubation and chemical extraction of soils as methods to determine N mineralization potential. This paper re-examines new and previously published data on net mineralization, with the aim of examining the relationships between soil thermal units, net N mineralization (measured using acetylene incubations) and dry matter production in pastures. Net N mineralization is expressed as N turnover (net N mineralization as a % of total soil N). Relationships are developed between soil thermal units, dry matter production, and N turnover. These relationships have potential in advising farmers on potential N mineralization from soil organic matter. A second use of such relationships is the modelling of N transformations in pasture systems. Further work should explore the effect of soil moisture on such relationships and examine the relationship between soil thermal units and uptake of N by pasture. |
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Keywords: | Nitrogen mineralization models prediction soil temperature pastures |
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