Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-11T02:49:59.312Z Has data issue: false hasContentIssue false
  • English
  • Français

A spatially explicit population model of the effect of spatial scale of heterogeneity in grass–clover grazing systems

Published online by Cambridge University Press:  02 April 2013

J. M. SHARP ,
G. R. EDWARDS  and
M. J. JEGER
J. M. SHARP*
Affiliation:
Division of Biology, Imperial College London, Wye Campus, Wye, Ashford, Kent TN25 5AH, UK
G. R. EDWARDS
Affiliation:
Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 84, Lincoln 7647, Canterbury, New Zealand
M. J. JEGER
Affiliation:
Division of Biology, Imperial College London, Wye Campus, Wye, Ashford, Kent TN25 5AH, UK
*
*To whom all correspondence should be addressed. Email: joanna.sharp@plantandfood.co.nz
Get access Rights & Permissions [Opens in a new window]

Summary

The benefits of using white clover (Trifolium repens L.) as a source of nitrogen (N) and nutritious feed in pasture grazed by ruminant livestock have been widely recognized. However, clover is considered inadequate and unreliable as the main source of N input, since its abundance in pasture is patchy, low (typically <0·20) and shows great year-to-year variation. This is thought to be due to the metabolic costs of N fixation, competition with grass, the preference for clover by grazing animals and patchy dung and urine deposition. One solution suggested by a number of authors is to increase the heterogeneity within the pasture by spatially separating clover from grass. This method of pasture management, in order to sustain higher clover content in both the sward and diet of grazing animals, would remove inter-specific competition and equalize grazing pressure, allowing clover to grow unimpeded in greater abundance than previously observed. An existing spatially explicit grass–clover simulation model, developed to investigate the intrinsic spatial and temporal variability within mixed grass–clover swards, was modified and then used to examine the impact of spatial separation on the content, variability and patchiness of clover in pasture. The results show that spatial separation increases both the content and spatial aggregation of clover and reduces year-to-year variation compared with a mixed pasture that fluctuates around a lower mean. The same model was also used to examine the impact of spatial separation across a range of spatial scales, from narrow strips to complete separation, as a means of managing the concerns over disruption to the N cycle within the pasture. The present study shows the importance of the initial sowing arrangement of plant species in sustaining a high content of clover within a pasture in the short term, to at least 20 years depending on the scale of separation, and demonstrates that the spatial separation of clover from grass within a grazed pasture may overcome some of the limitations associated with the use of clover in conventional grass–clover pastures. Results are discussed in terms of benefits to both herbage dry matter production and animal performance.

Type
Crops and Soils Research Papers
Information
The Journal of Agricultural Science , Volume 152 , Issue 3 , June 2014 , pp. 394 - 407
Copyright
Copyright © Cambridge University Press 2013 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Brock, J. L. & Hay, M. J. M. (2001). White clover performance in sown pastures: a biological/ecological perspective. Proceedings of the New Zealand Grassland Association 63, 73–83.CrossRefGoogle Scholar
Cain, M. L., Pacala, S. W., Silander, J. A. & Fortin, M. J. (1995). Neighborhood models of clonal growth in the white clover Trifolium-repens. American Naturalist 145, 888–917.Google Scholar
Caradus, J. R., Woodfield, D. R. & Stewart, A. V. (1996). Overview and vision for white clover. In White Clover: New Zealand's Competitive Edge. Symposium of the New Zealand Grassland Association (Ed. Woodfield, D. R.), pp. 1–6. Lincoln, NZ: Lincoln University.Google Scholar
Champion, R. A., Orr, R. J., Penning, P. D. & Rutter, S. M. (2004). The effect of the spatial scale of heterogeneity of two herbage species on the grazing behaviour of lactating sheep. Applied Animal Behaviour Science 88, 61–76.Google Scholar
Chapman, D. F., Parsons, A. J. & Schwinning, S. (1996). Management of clover in grazed pastures: expectations, limitations and opportunities. In White Clover: New Zealand's Competitive Edge. Symposium of the New Zealand Grassland Association (Ed. Woodfield, D. R.), pp. 55–64. Lincoln, NZ: Lincoln University.Google Scholar
Cosgrove, G. P., Parsons, A. J., Marotti, D. M., Rutter, S. M. & Chapman, D. F. (2001). Opportunities for enhancing the delivery of novel forage attributes. Proceedings of the New Zealand Society of Animal Production 61, 16–19.Google Scholar
Davies, D. A. & Hopkins, A. (1996). Production benefits of legumes in grassland. In Legumes in Sustainable Farming Systems (Ed. Younie, D.), pp. 234–246. British Grassland Society Occasional Symposium, No. 30. Reading, UK: British Grassland Society.Google Scholar
Doak, B. W. (1952). Some chemical changes in the nitrogenous constituents of urine when voided on pasture. Journal of Agricultural Science, Cambridge 42, 162–171.Google Scholar
Edwards, G. R., Parsons, A. J., Newman, J. A. & Wright, I. A. (1996). The spatial pattern of vegetation in cut and grazed grass/white clover pastures. Grass and Forage Science 51, 219–231.CrossRefGoogle Scholar
Edwards, G. R., Parsons, A. J. & Bryant, R. H. (2008). Manipulating dietary preference to improve animal performance. Australian Journal of Experimental Agriculture 48, 773–779.Google Scholar
Evans, D. R., Williams, T. A., Jones, S. & Evans, S. A. (1998). The effect of cutting and intensive grazing managements on sward components of contrasting ryegrass and white clover types when grown in mixtures. Journal of Agricultural Science, Cambridge 130, 317–322.Google Scholar
Fothergill, M., Davies, D. A., Morgan, C. T. & Jones, J. R. (1996). White clover crashes. In Legumes in Sustainable Farming Systems (Ed. Younie, D.), pp. 172–176. British Grassland Society Occasional Symposium, No. 30. Reading, UK: British Grassland Society.Google Scholar
Frame, J., Charlton, J. F. L. & Laidlaw, A. S. (1998). Temperate Forage Legumes. Wallingford, UK: CAB International.Google Scholar
Fraser, T. J. & Rowarth, J. S. (1996). Legumes, herbs or grass for lamb performance? Proceedings of the New Zealand Grassland Association 58, 49–52.Google Scholar
Ledgard, S. F. (1991). Transfer of fixed nitrogen from white clover to associated grasses in swards grazed by dairy-cows, estimated using N-15 methods. Plant and Soil 131, 215–223.Google Scholar
Ledgard, S. F. (2001). Nitrogen cycling in low input legume-based agriculture, with emphasis on legume/grass pastures. Plant and Soil 228, 43–59.Google Scholar
Ledgard, S. F., Sprosen, M. S. & Steele, K. W. (1996). Nitrogen fixation by nine white clover cultivars in grazed pasture, as affected by nitrogen fertilization. Plant and Soil 178, 193–203.Google Scholar
Marriott, C. A., Smith, M. A. & Baird, M. A. (1987). The effect of sheep urine on clover performance in a grazed upland sward. Journal of Agricultural Science, Cambridge 109, 177–185.Google Scholar
Nolan, T., Connolly, J. & Wachendorf, M. (2001). Mixed grazing and climatic determinants of white clover (Trifolium repens L.) content in a permanent pasture. Annals of Botany 88, S1, 713–724.Google Scholar
Orr, R. J., Penning, P. D., Parsons, A. J. & Champion, R. A. (1995). Herbage intake and N excretion by sheep grazing monocultures or a mixture of grass and white clover. Grass and Forage Science 50, 31–40.Google Scholar
Parsons, A. J. & Chapman, D. F. (2000). Principles of pasture growth and utilization. In Grass: its Production and Utilization. Third Edition (Ed. Hopkins, A.), pp. 31–89. Oxford, UK: Blackwell Science.Google Scholar
Parsons, A. J., Harvey, A. & Johnson, I. R. (1991 a). Plant animal interactions in a continuously grazed mixture. 2. The role of differences in the physiology of plant-growth and of selective grazing on the performance and stability of species in a mixture. Journal of Applied Ecology 28, 635–658.Google Scholar
Parsons, A. J., Orr, R. J., Penning, P. D., Lockyer, D. R. & Ryden, J. C. (1991 b). Uptake, cycling and fate of nitrogen in grass clover swards continuously grazed by sheep. Journal of Agricultural Science, Cambridge 116, 47–61.Google Scholar
Parsons, A. J., Newman, J. A., Penning, P. D., Harvey, A. & Orr, R. J. (1994). Diet preference of sheep – effects of recent diet, physiological-state and species abundance. Journal of Animal Ecology 63, 465–478.CrossRefGoogle Scholar
Parsons, A. J., Edwards, G. R., Chapman, D. F. & Carran, R. A. (2006). How far have we come: 75 years ‘in clover’? Proceedings of the New Zealand Grassland Association 68, 7–13.Google Scholar
Racz, E. V. P. & Karsai, J. (2006). The effect of initial pattern on competitive exclusion. Community Ecology 7, 23–33.Google Scholar
Rutter, S. M. (2006). Diet preference for grass and legumes in free-ranging domestic sheep and cattle: current theory and future application. Applied Animal Behaviour Science 97, 17–35.Google Scholar
Rutter, S. M., Orr, R. J., Penning, P. D., Yarrow, N. H. & Champion, R. A. (2002). Ingestive behaviour of heifers grazing monocultures of ryegrass or white clover. Applied Animal Behaviour Science 76, 1–9.Google Scholar
Ryden, J. C. (1984). The Flow of Nitrogen in Grassland. Proceedings No. 229. London: Fertiliser Society London.Google Scholar
Schwinning, S. & Parsons, A. J. (1996 a). Analysis of the coexistence mechanisms for grasses and legumes in grazing systems. Journal of Ecology 84, 799–813.CrossRefGoogle Scholar
Schwinning, S. & Parsons, A. J. (1996 b). A spatially explicit population model of stoloniferous N-fixing legumes in mixed pasture with grass. Journal of Ecology 84, 815–826.Google Scholar
Schwinning, S. & Parsons, A. J. (1996 c). Interaction between grasses and legumes: understanding variability in species composition. In Legumes in Sustainable Farming Systems (Ed. Younie, D.), pp. 153–163. British Grassland Society Occasional Symposium, No. 30. Reading, UK: British Grassland Society.Google Scholar
Sharp, J. M. (2007). Use of novel spatial presentations of plant species to improve legume abundance. Ph.D. Thesis, University of London.Google Scholar
Sharp, J. M., Edwards, G. R. & Jeger, M. (2012 a). Impact of the spatial scale of grass-legume mixtures on sheep grazing behaviour, preference and intake, and subsequent effects on pasture. Animal 6, 1848–1856.Google Scholar
Sharp, J. M., Edwards, G. R. & Jeger, M. (2012 b). Impact of spatial heterogeneity of plant species on pasture productivity, quality and ewe and lamb performance in continuously stocked grass-clover pasture. Grass and Forage Science DOI: 10.1111/gfs.12027.Google Scholar
Silvertown, J., Holtier, S., Johnson, J. & Dale, P. (1992). Cellular automaton models of interspecific competition for space – the effect of pattern on process. Journal of Ecology 80, 527–534.Google Scholar
Thornley, J. H. M. (1998). Grassland Dynamics: An Ecosystem Simulation Model. Wallingford, Oxon: CAB International.Google Scholar
Thornley, J. H. M., Bergelson, J. & Parsons, A. J. (1995). Complex dynamics in a carbon-nitrogen model of a grass legume pasture. Annals of Botany 75, 79–94.CrossRefGoogle Scholar
Whitehead, D. C. (1995). Grassland Nitrogen. Wallingford: CAB International.CrossRefGoogle Scholar
Williams, T. A., Evans, D. R., Rhodes, I. & Abberton, M. T. (2003). Long-term performance of white clover varieties grown with perennial ryegrass under rotational grazing by sheep with different nitrogen applications. Journal of Agricultural Science, Cambridge 140, 151–159.Google Scholar