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Sample size and sampling intensity in relation to the precision of small-plot herbage sward trials

Published online by Cambridge University Press:  27 March 2009

C. A. Foster  and
C. E. Wright
C. A. Foster
Affiliation:
Plant Breeding Station, Loughgall, Co. Armagh, Northern Ireland
C. E. Wright
Affiliation:
Plant Breeding Station, Loughgall, Co. Armagh, Northern Ireland
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Summery

Three sampling experiments were conducted to examine the effect of sample size and sampling intensity on the precision of dry-matter content and botanical composition estimates of perennial rye-grass-white clover herbage. One of these experiments examined the between-sample variability of these attributes and of dry-matter yield in relation to other sources of experimental error in a small-plot sward trial. The sample sizes examined were 800 g, 400 g, 200 g, 100 g, 50 g and 25 g green weight. In general the accuracy of dry-matter content and botanical composition estimates decreased with decreasing sample size. The between-sample variabilities of 25 g and 50g samples were high in relation to their between-plot variabilities. Single 100 g samples provided reasonably good estimates of these attributes and of dry-matter yield, but single 200 g samples provided a more satisfactory margin for error. Samples larger than 200 g appeared to be unnecessary. When weight-for-weight comparisons of single and duplicate samples were made there appeared to be little advantage in duplicate sampling. A theoretical examination of measurement inaccuracies inherent in the techniques used in small-plot sward trialssuggested that variation in plot length measurements in particular may make an undesirable contribution to the variability of such trials. A procedure for the conduct of small-plot trials is recommended. It is concluded that, where plot size and replication are limited, further improvement in the precision of such trials will not be readily attainable.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 70 , Issue 1 , February 1968 , pp. 19 - 27
Copyright
Copyright © Cambridge University Press 1968

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References

Alder, F. E. (1963). A comparison of the productivity of Aberystwyth-bred and commercial grass varieties in small farm units. I. J. Br. Orassld Soc. 18, 146.CrossRefGoogle Scholar
Bartlett, M. S. & Greenhill, A. W. (1936). The relative importance of plot variation and of field and laboratory sampling errors in small plot pasture productivity experiments. J. agric. Sci., Oamb. 26, 258.CrossRefGoogle Scholar
Castle, M. E. & Reid, D. (1960). A comparison of lucerne varieties in south-west Scotland. J. Br. Qrassld Soc. 15, 281.Google Scholar
Chestnutt, D. M. B. & Rutherford, A. A. (1965). The effect of sample size on the precision of botanical composition estimates. Rec. agric. Res. Minist. Agric. Nth. Ire. 14, 1.Google Scholar
Commonwealth Aoricultubal Bureaux (Comm. Bur. Past, and Fd Crops). Bull. no. 45 (1961). Research techniques in use at the Grassland Research Institute, Hurley.Google Scholar
Davies, W. E. & Tyler, B. F. (1962). The yields of lucerne varieties in West Wales. J. Br. Orassld Soc. 17, 218.CrossRefGoogle Scholar
Dent, J. W. & Aldrich, D. T. A. (1963). The interrelationships between heading date, yield, chemical composition and digestibility in varieties of perennial ryegrass, timothy, cocksfoot and meadow fescue. J. natn. Inst. agric. Bot. 9, 261.Google Scholar
Feltner, K. C. & Massengale, M. A. (1965). The influence of temperature and harvest management on growth, level of carbohydrates in the roots, and survival of alfalfa (Medicago saliva). Crop Sci. 5, 585.CrossRefGoogle Scholar
Green, J. O., Langer, H. J. & Williams, T. E. (1952). Sources and magnitudes of experimental errors in grazing trials. Proc. §th int. Orassld Congr. p. 1374.Google Scholar
Jackobs, J. A. (1963). A measurement of the contribution of ten species to pasture mixtures. Agron. J. 55, 127.CrossRefGoogle Scholar
Langille, J. E. & Warren, F. S. (1964). Influence of time of seeding on establishment and persistence of species and yield of forage mixtures. Can. J. PI. Sci. 44, 78.CrossRefGoogle Scholar
Lynch, P. B. (1960). Conduct of field experiments. Bull. Dept. Arigc. N.Z. no. 399.Google Scholar
Petersen, R. G. & Lucas, H. L. (1960). Experimental errors in grazing trials. Proc. 8th int. Orassld Congr. p. 747.Google Scholar
Rogers, H. H. & Lazbnby, A. (1966). The evaluation and with clover only, under simulated pasture condiof grasses in micro-plots. J. agric. Sri., Camb. 66, 147CrossRefGoogle Scholar
Sampford, M. R. (1960). Some statistical problems in Estimates of herbage yields and consumption. Proc. 8th int. Qrassld Congr. p. 742.Google Scholar
Stewart, T. A., Brown, S. M. & Boyd, M. (1966). Relative production of six perennial ryegrass cultivars clipping and nitrogen on competition between three grown with and without clover plus artificial nitrogen and with clover only, under simulated pasture conditions. Rec. agric. Res. Minist. Agrio. Nth Ire. 15, 99.Google Scholar
Torrie, J. H., Schmidt, D. R. & Tenpas, G. H. (1963). Estimates of optimum plot size and shape and replicate number for forage yield of alfalfa-bromegrass mixtures. Agron. J. 55, 258.Google Scholar
Wilson, D. B. & McGuire, W. S. (1961). Effects of clipping and nitrogen on competition between three pasture species. Can. J. PI. Sci. 41, 631.CrossRefGoogle Scholar