Herbage measurement <i>in situ</i> by electronics. 1. The multiple‐probe‐type capacitance meter: a brief review

Angelone, Alfonso; Toledo, José Manuel Almendros; Burns, J. C.

doi:10.1111/j.1365-2494.1980.tb01489.x

Cited by 8 publications

(7 citation statements)

References 20 publications

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“…If the antenna is approximated by a disk of diameter D, then the angular dependence of both the transmitted and received power is the Airy diffraction pattern [47]. The use of a sensor array changes (6) to:…”

Section: Sensor Arrays and Beam-formingmentioning

confidence: 99%

“…Satellite, aerial, and ground-based platforms equipped with advanced sensors provide the potential for fast, non-destructive, and low-cost monitoring of plant growth, development, and yield in a field environment [3]. The methods currently used include the measurement of parameters such as capacitance, spectral properties, pasture height (known as sward height), and compressed sward height [4][5][6][7][8][9][10][11][12]. A wide range of optical sensors have been used to measure a range of parameters of crops and pastures, including biomass [9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…The current work describes a new proximal sensor, and satellite and airborne methods will not be discussed in detail. However, for more information, the reader is referred to review papers such as those provided in references [3,[6][7][8][9][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Ultrasonic Proximal Sensing of Pasture Biomass

Legg

Bradley²

2019

Remote Sensing

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The optimization of pasture food value, known as ‘biomass’, is crucial in the management of the farming of grazing animals and in improving food production for the future. Optical sensing methods, particularly from satellite platforms, provide relatively inexpensive and frequently updated wide-area coverage for monitoring biomass and other forage properties. However, there are also benefits from direct or proximal sensing methods for higher accuracy, more immediate results, and for continuous updates when cloud cover precludes satellite measurements. Direct measurement, by cutting and weighing the pasture, is destructive, and may not give results representative of a larger area of pasture. Proximal sensing methods may also suffer from sampling small areas, and can be generally inaccurate. A new proximal methodology is described here, in which low-frequency ultrasound is used as a sonar to obtain a measure of the vertical variation of the pasture density between the top of the pasture and the ground and to relate this to biomass. The instrument is designed to operate from a farm vehicle moving at up to 20 km h−1, thus allowing a farmer to obtain wide coverage in the normal course of farm operations. This is the only method providing detailed biomass profile information from throughout the entire pasture canopy. An essential feature is the identification of features from the ultrasonic reflectance, which can be related sensibly to biomass, thereby generating a physically-based regression model. The result is significantly improved estimation of pasture biomass, in comparison with other proximal methods. Comparing remotely sensed biomass to the biomass measured via cutting and weighing gives coefficients of determination, R2, in the range of 0.7 to 0.8 for a range of pastures and when operating the farm vehicle at speeds of up to 20 km h−1.

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Section: Sensor Arrays and Beam-formingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrasonic Proximal Sensing of Pasture Biomass

Legg

Bradley²

2019

Remote Sensing

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“…In some cases, the legs are omitted and the instrument rests on the probes. The "earth-plate" meters operate on a slightly different basis from the probe types with a plate capacitor parallel to the ground surface (Angelone et al 1980a, 1980band Toledo et al 1980. In actual use readings are taken on several placements of the instrument and the herbage beneath the instrument clipped in a double-sampling procedure.…”

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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“…The possible reason for these conflicting reports is that MR is affected by a number of external factors such as plant moisture level (Jones & Haydock 1970;Johns 1972;Angelone et al 1980), the effect of dead herbage (Currie et al 1973;, and the effect of sward compaction through trampling and lodging (Campbell et al 1%2;Jones & Haydock 1970). Unsatisfactory results may be obtained if such factors are not accounted for in the operation .…”

Section: Introductionmentioning

confidence: 99%

Factors influencing the accuracy of herbage mass determinations with a capacitance meter

1983

New Zealand Journal of Experimental Agriculture

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Herbage measurement in situ by electronics. 1. The multiple‐probe‐type capacitance meter: a brief review

Cited by 8 publications

References 20 publications

Ultrasonic Proximal Sensing of Pasture Biomass

Ultrasonic Proximal Sensing of Pasture Biomass

Rangeland vegetation productivity and biomass

Factors influencing the accuracy of herbage mass determinations with a capacitance meter

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