The electronic measurement of the yield of growing pasture I. A statistical assessment

Alcock, M. B.; Lovett, J. V.

doi:10.1017/s0021859600017822

Cited by 16 publications

(16 citation statements)

References 3 publications

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“…Since sample cutting will be needed for each plot, or at least for each experimental treatment, the amount of work required will exceed that anticipated by other workers who have used such devices (Campbell et al 1962;Johns & Watkin, 1965;Alcock & Lovett, 1967). The method has, however, proved to be of value in grazing experiments where large plots have to be sampled.…”

Section: Possibilities and Problems Of The Proposed New Methodsmentioning

confidence: 99%

“…Since our meter readings have been corrected for residue, and since the meter reads to ground level, the bias is not due to different proportions of total herbage remaining after cutting as might have occurred in the study by Alcock & Lovett (1967). Back (1968) has emphasized the magnitude of the residual variation due to differences between days obtained by the use of an overall prediction equation, although he was unable to reduce this using dry matter percentage and a number of climatic variables.…”

Section: Use Of Relative Water Content In An Overall Predictionmentioning

confidence: 98%

“…1962;Johns & Watkin, 1965;Neal & Neal, 1966;Back, 1968). Some workers have shown that the use of water content can reduce the differences that exist between pastures, Alcock (1964), Alcock & Lovett (1967), whilst Back (1968 has shown little effect of dry matter percentage in improving the relation. It is not known whether meter reading was actually compared with weight of water in the latter case.…”

Section: Use Of Relative Water Content In An Overall Predictionmentioning

confidence: 99%

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Yield estimation of tropical and temperate pasture species using an electronic capacitance meter

Jones¹,

Haydock

1970

J. Agric. Sci.

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Modifications to the New Zealand meter (Campbell, Phillips & O'Reilly, 1962) are briefly described and the results obtained with the modified meters presented.Water was shown to have the dominant influence on meter reading-dessication of the plant material reduced readings, application of water increased readings.The relation between yield of water (W) and meter reading (MR) depended on the circuitry of the meter used and was similar to that between capacitance change induced by a variable capacitor and meter reading. With the new meters this relation was strongly linear. For individual species the simple correlation of W on MR was generally superior to that for weight of dry matter. Regression coefficients for weight of water on meter reading differed between species and/or days but were correlated with the relative water content of the species (RW). Inclusion of RW in addition to that of W increased the variation accounted for (V %) when all species were included from 76-0 to 86-9 %. However, the multiple regression did not eliminate bias. For individual species, there was no benefit in including the RW term.The inclusion of height of herbage (H) in a multiple regression equation with weight of water greatly improved the V % when compared with the regression of meter reading on weight of water alone for oats dressed with three levels of nitrogen. The V % increased from 71-3 % for W alone to 90'0% when W, H and H a •were included in the regression. Further testing using height of herbage over a wide range of species will be required to confirm this improvement for use in an overall regression.Emphasis is placed on the very strong linear relation between yield (of water or dry matter) and meter reading within any one pasture at any one time. Use is made of this relation in the presentation of a new method, which overcomes the bias associated with prediction equations, for estimating pasture yields. This entails establishing the mean reading for any pasture and cutting for yield estimation three samples having such a mean. The limitations of the method for use with mixtures is discussed. t * ie °k.) ect being to summarize the results achieved, to describe a new method for estimating pasture Work at the Cunningham Laboratory on an yields and to determine the factors which are being electronic capacitance meter for the measurement measured by the meter. of pasture yields commenced in 1962 when plans of Basically the meter is a radio frequency (B.F.) the New Zealand model (Campbell et al. 1962) were tuned circuit (see below) in which the probes are forwarded to us. a condenser. Since that time considerable testing of the unitThe frequency of oscillation of the R.F. circuit is followed by modifications has occurred. These have related to the capacitance between the electrodes of been reported on briefly in annual reports of the the condenser by the formula: C.S.I.R.O. Division of Tropical Pastures 1963-67. Details of the modifications are not reported here, / ~ 1[(2ITJ(CL)),

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Section: Possibilities and Problems Of The Proposed New Methodsmentioning

confidence: 99%

Section: Use Of Relative Water Content In An Overall Predictionmentioning

confidence: 98%

Section: Use Of Relative Water Content In An Overall Predictionmentioning

confidence: 99%

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Yield estimation of tropical and temperate pasture species using an electronic capacitance meter

Jones¹,

Haydock

1970

J. Agric. Sci.

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“…Campbell et al (1962 described a model with several improvements over earlier models and Neal and Neal (1965) described their "Heterodyne Vegetation Meter". Different meters have been described by Alcock (1964), Johns et al (1965), Alcock and Lovett (1967), Kreil and Matschke (1968), and Van Dyne et al (1968).…”

Section: Capacitance Metersmentioning

confidence: 99%

Rangeland vegetation productivity and biomass

Pieper¹

1988

Vegetation Science Applications for Rangeland Analysis and Management

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Herbage weight or biomass is an important characteristic for range vegetation since it supports directly or indirectly all consumer groups. Plant biomass is also important as a measure of dominance in plant communities. Many methods have been devised to estimate plant biomass, but all have some limitations. Estimation techniques, either by plot or plant, often involve a double sampling procedure to improve on the estimates. Direct harvesting is a destructive sampling procedure which is often used when biomass is the response measured in research studies. Precipitation has been used as an independent variable to predict end-of-season biomass. However, considerable data are necessary to develop reliable relationships. Capacitance meters, biomass meters, and p-attenuation techniques have promise for specific situations, but have not received widespread support among range researchers and ecologists. All these techniques require considerable calibration before they can be used for specific situations. Plant biomass data are useful for establishing dominance of individual species, estimating livestock stocking rates, and determining range condition. IntroductionMeasurement of plant biomass or standing crop has been of interest to range workers for some time because herbivores depend directly upon plant biomass for their food. Interest in production ecology is of more recent emphasis by plant ecologists, particularly during the International Biological Program Studies during the 1970's (Milner and Hughes 1968). These studies illustrate the importance of plant biomass as an indicator of general ecological importance of individual plants and communities.

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“…Data which have shown the value of capacitance probes as a means of making non-destructive measurements of pasture growth have been published by several workers (1,2,3,5). This technique has been shown to be applicable to monocultures of grasses and legumes and to mixtures of grasses and legumes; but, there are no recorded results with field crops.…”

Section: Introductionmentioning

confidence: 99%

THE ELECTRONIC MEASUREMENT OF THE YIELD OF RAPE (Brassica napus)

Lovett

Bofinger

1970

Grass and Forage Science

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The electronic measurement of the yield of growing pasture I. A statistical assessment

Abstract: 1. A modified capacitance meter used to make rapid non-destructive measurements of growingpasture is briefly described.

Cited by 16 publications

References 3 publications

Yield estimation of tropical and temperate pasture species using an electronic capacitance meter

Yield estimation of tropical and temperate pasture species using an electronic capacitance meter

Rangeland vegetation productivity and biomass

THE ELECTRONIC MEASUREMENT OF THE YIELD OF RAPE (Brassica napus)

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