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The design and conduct of experiments to measure animal and herbage production responses to fertilizer nitrogen under cutting and grazing managements

Published online by Cambridge University Press:  27 March 2009

R. V. Large ,
J. M. Cobby  and
R. D. Baker
R. V. Large
Affiliation:
The Grassland Research Institute, Hurley, Maidenhead, Berkshire, SL6 5LR
J. M. Cobby
Affiliation:
The Grassland Research Institute, Hurley, Maidenhead, Berkshire, SL6 5LR
R. D. Baker
Affiliation:
The Grassland Research Institute, Hurley, Maidenhead, Berkshire, SL6 5LR
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Summary

Two experiments were conducted to provide information on the precision of herbage sampling, the degree of replication and the logistics of managing rotational and continuous grazing experiments. In a third experiment the possibility of estimating herbage growth, during the rotational grazing of paddocks for 4 days, by linear extrapolation of measured growth estimates made during the interval between grazings was investigated. A fourth experiment was then conducted to investigate animal and herbage production responses to nitrogen applied at five levels over the range 80–900 kg N/ha with three replicates per treatment.

Results from Expts 1 and 2 showed that similar precision could be obtained under both rotational and continuous systems of grazing with the same number of replicates and samples of herbage. There was little advantage in having more than three replicates and four samples per paddock or two replicates and eight samples per paddock. Under continuous grazing a 3-weekly sampling and movement of exclosure cages was indicated. It was also found, from Expt 3 that, under rotational grazing, linear extrapolation of growth from 0–24 days did not reflect growth to 28 days in a consistent manner. Six animals per treatment, permanently in the paddocks, proved adequate for the estimation of live-weight gain.

Experiment 4 confirmed that response curves could be fitted with an acceptable degree of precision if there was one low, one very high, and two intermediate levels of nitrogen. Adjustment of the number of animals to maintain sward height at between 5 and 7 cm ensured similar sward conditions and rates of live-weight gain across all treatments.

The problems associated with the measurement of herbage production under grazing are discussed.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 104 , Issue 1 , February 1985 , pp. 85 - 94
Copyright
Copyright © Cambridge University Press 1985

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References

Bosch, S. (1956). The determination of pasture yields. Netherlands Journal of Agricultural Science 4, 305–313.CrossRefGoogle Scholar
Brown, D. (1954). Methods of surveying and measuring vegetation. Bulletin 42. Hurley, Berks.: Commonwealth Bureau of Pastures and Field Crops.Google Scholar
Cobby, J. M., Chapman, P. F., Reeks, J. M. & Pike, D. J. (1983). The design and analysis of nitrogen response experiments. Annual Report Grassland Research Institute, Hurley, 1982, p. 121.Google Scholar
Forbes, T. J., Dibb, C, Green, J. O., Hopkins, A. & Peel, S. (1980). Factors affecting the productivity of permanent grassland. A National Farm Study. 141 pp. Hurley: Grassland Research Institute – Agricultural Development and Advisory Service, Joint Permanent Pasture Group.Google Scholar
Frame, J. (1981). Herbage mass. In Sward Measurement Handbook (ed. Hodgson, J., Baker, R. D., Davies, Alison, Laidlaw, S., and Leaver, J. D.), pp. 39–69. Hurley, Berks.: British Grassland Society.Google Scholar
Grassland Research Institute (1961). Research techniques in use at the Grassland Research Institute, Hurley. Bulletin 45. Hurley, Berks.: Commonwealth Bureau of Pastures and Field Crops.Google Scholar
Holmes, C. W. (1974). The Massey Grass Meter. Dairy Farming Annual 1974, 26–30.Google Scholar
Jackson, M. V. & Williams, T. B. (1979). Response of grass swards to fertilizer N under cutting or grazing. Journal of Agricultural Science, Cambridge 92, 549–562.CrossRefGoogle Scholar
Klingman, D. L., Miles, S. R. & Mott, G. O. (1943). The cage method for determining consumption and yield of pasture herbage. Journal of the American Society of Agronomy 35, 739–746.CrossRefGoogle Scholar
Linehan, P. A., Lowe, J. & Stewart, R. H. (1947). The output of pasture and its measurement. Part II. Journal of the British Grassland Society 2, 145–168.CrossRefGoogle Scholar
T'Mannetje, L. (1978). Measurement of grassland vegetation and animal production. Bulletin 52. Hurley, Berks.: Commonwealth Bureau of Pastures and Field Crops.Google Scholar
Morrison, J., Jackson, M. V. & Sparrow, P. E. (1980). The response of perennial ryegrass to fertilizer nitrogen in relation to climate and soil. Technical Report No. 27. Hurley, Berks.: Grassland Research Institute.Google Scholar
Parsons, A. J., Collbtt, B. & Lewis, J. (1984). Changes in the structure and physiology of a perennial ryegrass sward when released from a continuous stocking management – implications for the use of exclusion cages in continuously stocked swards. Grass and Forage Science 39, 1–9.CrossRefGoogle Scholar
Pollott, G. E. & Kilkenny, J. B. (1977). An investigation of the factors influencing the utilised output from grassland. Animal Production 24, 161.Google Scholar
Tallowin, J. R. B. (1981). An interpretation of tiller number changes under grazing. In Plant Physiology and Herbage Production. British Grassland Society Occasional Symposium No. 13, (ed. Wright, C. E.), pp. 77–80.Google Scholar
Waddington, J. & Cook, D. A. (1971). The influence of sample size and number on the precision of estimates of herbage production and consumption in two grazing experiments. Journal of the British Grassland Society 26, 95–101.CrossRefGoogle Scholar