An Evaluation of an Electronic Instrument for Pasture Yield Estimation

The capacitance meters available in tbe past for estimating herbage yields bave lacked sensitivity at the extremes of tbeir range of measurement. Tbe preliminary evaluation of a bigbly sensitive capacitance meter described here indicates tbat accurate measurement is possible in tbe range 0-1100 kg DM/ba. Tbe implications of tbis development for tbe measurement of herbage of low availability are discussed.

Section: Discussionsupporting

confidence: 73%

“…Back (2), and a strong quadratic component is a feature of the relationship developed between MR and herbage yield parameters in the current work. This component was consistent over the four pasture types measured.…”

Section: Materuls and Methodsmentioning

confidence: 93%

The Electronic Measurement of Small Herbage Yields Using a High Sensitivity Capacitance Meter

Lovett¹,

Burchi²

1972

“…The various capacitance meters previously mentioned have been extensively field tested with mixed results. Several workers have reported promising results using these devices (Campbell et al, 1962;Alcock and Lovett, 1967;Back, 1968;Van Dyneef a/., 1968;Back et al, 1969;Johns, 1972;Currie et al, 1973;Neal and Neal, 1973) while others have found that there are too many sources of error which prohibit successful field usage of these devices in many field situations (Bryant et al, 1971).…”

Section: Capacitance Metersmentioning

confidence: 99%

A critical review of remote sensing and other methods for non‐destructive estimation of standing crop biomass

Tucker

1980

101

Several different techniques for the non-destructive estimation of pasture or range biomass are critically reviewed and compared to remote sensing methods. Similarities and differences between the visual estimation procedure, )S-attentuation, capacitance meters, weighted disc, and spectral methods are discussed in terms of accuracy, time, ease of operation, operational constraints and calibration procedures. No one technique has been shown to be superior across the board to the other techniques reviewed for ground-based biomass estimatiori. A discussion of the strengths and weaknesses of each non-destructive method allows for the selection of the technique most suited to a particular application.

“…Although high multiple correlation coefficients can occur with unacceptably high residual sums of squares (Back, 1968), we used them as summary statistics. These show relative performances of different regressor (independent) and regressand (dependent) variables, without necessarily being of use in determining whether the meter and associated regressors adequately predict a particular pasture parameter.…”

Section: (D) Statistical Analysismentioning

confidence: 99%

Limitations of the electronic capacitance meter in measuring yields of grazed tropical pastures

Jones

Sandland

Bunch

1977

Relationships between readings of the electronic (capacitance) pasture meter and descriptions of pasture yield were examined over the yearly growth cycle in grazed pastures of Setaria anceps cv. Nandi, with or without Macroptilium atropurpurem cv. Siratro and Desmodium intortum cv. Greenleaf. There was a poor relationship between meter reading and pasture dry matter yield (r = +0-574 pooled over pastures and seasons) but this relationship was improved to r = +0-750 by inclusion of other regressors describing pasture height and proportion of inert material. Meter reading was more closely related to fresh pasture yield (r = +0-830), water yield (r = +0-885) or dried green yield (r = +0-830), although inclusion of a pasture height term still improved the relationship slightly. Suggestions are made about using the meter to estimate dried green yield rather than total dry matter yield, and taking more consideration of the proportion of inert material when relating the meter reading to total dry matter yield.Visual estimation was also compared with actual pasture yield measured by cutting. Even though prior training for yield estimation was inadequate, the relationships between visually estimated and actual yield were as good as those from the pasture meter. It is concluded that the pasture meter will not find a regular use as a sampling tool in most grazed tropical pastures.