Abstract
The stable isotope15N is particularly valuable in the field for measuring N fixation by isotope dilution. At the same time other soil-plant processes can be studied, including15N recovery, and nitrogen transfer between clover and grass. Three contrasting sites and soils were used in the present work: a lowland soil, an upland soil, and an upland peat. Nitrogen fixation varied from 12 gm−2 on lowland soil to 2.7 gm−2 on upland peat. Most N transfer occurred on upland soil (4.2 gm−2) which, added to nitrogen fixed, made a total of 8.7 gm2 input during summer 1985.15N recovery for the whole experiment was small, around 25%.
Measurement of dead and dying leaves, stubble and roots, suggests that plant organ death is the first stage in N transfer from white clover to ryegrass, through the decomposer cycle. Decomposition was fastest on lowland soils, slowest on peat. On lowland soil this decomposer nitrogen is apparently subverted before transfer, probably by soil microbes.
Variations in natural abundance of15N in plants were found in the two species on the different soils. These might be used to measure nitrogen fixation without adding isotope, but the need for many replicates and repeat samples would limit throughput.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Amarger N et al. 1979 Estimate of symbiotically fixed nitrogen in field-grown soybeans using variations in15N natural abundance. Plant and Soil 52, 269–280.
Barrie A and Workman C T 1984 An automated analytical system for nutritional investigations using15N tracers. Spectroscopy: An International Journal 3, 439–447.
Begon M and Mortimer M 1986 Population Ecology: A Unified Study of Animals and Plants. Second Edition. Blackwell, Oxford.
Dowdell R J and Webster C P 1980 A lysimeter study using nitrogen-15 on the uptake of fertiliser, nitrogen by perennial ryegrass swards and losses by leaching. J. Soil Sci. 31, 65–75.
Goodman P J and Collison M 1984 Growth, nitrogen uptake and fixation by ryegrass-white clover mixtures on Welsh upland soils.In Forage Legumes. Ed. D J Thompson. pp 199–200 Occasional symposium No. 16 British Grassland Society, Maidenhead.
Goodman P J and Collison M 1986 Effect of three clover varieties on growth,15N uptake and fixation by ryegrass/white clover mixtures at three sites in Wales. Grass and Forage Science 41, 191–198.
Haystead A 1981 Nitrogen fixation and the transfer of fixed nitrogen to associated grass.In Sward Measurement Handbook. Eds. J Hodgson, R D Baker, Alison Davies, A S Laidlaw and J D Leaver, pp 229–242. British Grassland Society, Maidenhead.
Haystead A and Marriott C 1979 Transfer of legume nitrogen to associated grass. Soil Biol. Biochem. 11, 99–104.
Humphries E C 1956 Mineral components and ash analysis.In Modern Methods of Plant Analysis 1. Eds. K Paech and M V Tracey. pp 468–502 Springer-Verlag, Berlin.
Starr C et al. 1984 Measurement of the nitrogen content of plant breeding material using a Carlo Erba Nitrogen Analyser. J. Agric. Sci. Camb. 103, 471–473.
Vose P B 1980 Introduction to Nuclear Techniques in Agronomy and Plant Biology. Pergamon, Oxford.
Walker T W et al. 1954 The nitrogen economy of grass legume associations. J. Br. Grassld Soc. 9, 249–274.
Wilson J K 1942 The loss of nodules from legume roots and its significance. J. Am. Soc. Agron. 34, 460–471.
Wolf G 1964 Isotopes in Biology. Academic Press. London.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Goodman, P.J. Nitrogen fixation, transfer and turnover in upland and lowland grass-clover swards, using15N isotope dilution. Plant Soil 112, 247–254 (1988). https://doi.org/10.1007/BF02140002
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02140002