Evaluation of weighted disc meter for pasture yield estimation on intensively stocked dairy pasture

Powell, Todd

doi:10.1080/03015521.1974.10427682

Cited by 17 publications

(17 citation statements)

References 4 publications

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“…The relationship between forage bulk and pasture phytomass yield generally has been strong. Correlation coefficients greater than 0.90 often have been reported (Alexander et al 1962, Bransby et al 1977, Castle 1976, Powell 1974, Santillan et al 1979, Shrivastava et al 1969. Because forage bulk is a measure of "compressed volume"of forage, it integrates both ward height and density into a single, three-dimensional quantity, This is believed to explain its value as a predictor of phytomass yield (Alexander et al 1962, Michalk andHerbert 1977).…”

mentioning

confidence: 97%

“…Both pasture height (Bakhuis 1960, Michalk and Herbert 1977, Whitney 1974 and forage bulk (Bransby etal. 1977, Powell 1974) have beenemployed successfully as predictors of pasture phytomass.…”

mentioning

confidence: 99%

“…1962) to&borate mechanismswhichemploycounters and gears to automatically determine and record the resting height ofametal plate (Earleand McGowan 1979). Most numerous ofall, however, are "disc meters" employing circular plates constructed from wood (Baker et al 1981) or metal (Castle 1976, Powell 1974, Santillan et al 1979). These devices, while generally useful to determine forage bulk.…”

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confidence: 99%

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A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk

Sharrow¹

1984

Journal of Range Management

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A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk

Sharrow¹

1984

Journal of Range Management

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“…Powell (1974) found that the weighted disc gave a poor performance in autumn, while Vartha & Matches (1977) found a poor relationship between yield and disc readings when there was an accumulation of dead material.…”

Section: Methodsmentioning

confidence: 99%

Visual estimates of available herbage on hill country sheep pastures

Baars¹,

Dyson²

1981

New Zealand Journal of Experimental Agriculture

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Available standing herbage over a range of sheep-grazed hill pastures was visually estimated by the same observer at regular intervals throughout the year. The results were compared with dry matter (DM) yield cuts from nine quadrats sited within each paddock. Linear regressions of yield on visual estimates were significant at all times (r 2 = 0.6-0.9). The analyses showed that the same observer can consistently assess paddock differences throughout the year and between years without using yield cut calibrations. However, the conversion of visual estimates to DM yield values was only possible on occasions in spring and early summer when pastures were green and residual coefficients of variability (RCV) were low. At other times of the year, when RCV values were high, the observer tended to under-estimate total DM over whole paddocks by over-estimating the green fraction and under-estimating the dead material and had difficulty in maintaining consistency with between-paddock assessments of paddocks of widely differing sward densities. Scoring a number of small plots within each paddock is preferable to whole-paddock estimation methods.

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“…In some experiments the relationship between herbage mass and meter reading has been relatively constant for extended periods within seasons, especially over the winter (Phillips and Clarke, 1971;Powell, 1974;Earieand McGowan, 1976) although the relationship commonly varies between seasons (Phillips and Clarke, 1971;Powell, 1974;Vartha and Matches, 1977;Bransby et al, 1977), between species (Castle, 1976 and with different managements such as irrigation (Powell, 1974), This variability in relationship indicates that it may sometimes be necessary to develop local calibration regressions for each treatment plot and sampling date. In other situations, however, it appears possible to pool calibration data for a range of swards over some time period.…”

Section: Introduetionmentioning

confidence: 99%

Value of a rising‐plate meter for estimating herbage mass of grazed perennial ryegrass‐white clover swards

Michell¹

1982

Grass and Forage Science

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A rising-plate meter was used in a double sampling tecbnique to measure the herbage mass of rotationally grazed perennial ryegrass-white clover swards over a period of 2 years. The meter was calibrated by developing a linear regression between meter reading and herbage dry matter mass as measured by cutting 0-2-m^ quadrats to ground level.There was a strong relationship between meter reading and herbage mass, and correlation coefficients were consistently 0-8 or above. The calibration regression was normally constant for extended periods, especially over the winter and spring. The relationship was more variable over the summer but appeared to follow a pattern that was to some extent repeatable between years. The slope of the regression (kg DM ha~' cm~') was 312 and 267 in the two winters and reached values of 800 and 452 in the two summers. The calibration relationship was adequately described by a linear model over the winter and spring but there was a tendency for a curved relationship in midto late summer.The standard pooled regression found with winter ryegrass-clover swards was not applicable to the more erect prairie grass, and the standard regression overestimated slightly the yield of heavily grazed swards. There was no evidence ofa difference in relationship between irrigated and non-irrigated swards over the summer.The individual meter readings could be used to develop a useful diagrammatic picture of the Correspondence: Mr P, Michell, Mt, Pleasant Laboratories,

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Evaluation of weighted disc meter for pasture yield estimation on intensively stocked dairy pasture

Cited by 17 publications

References 4 publications

A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk

A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk

Visual estimates of available herbage on hill country sheep pastures

Value of a rising‐plate meter for estimating herbage mass of grazed perennial ryegrass‐white clover swards

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