An improved electronic capacitance meter for estimating herbage mass

Abstract

An improved electronic capacitance pasture meter is described, and data on its calibration and use in a grazing trial are presented. The instrument is light (1 -4 kg) and portable, and uses integrated circuits to record the readings from a number of sampled sites. It has a digital display and can be constructed for a modest cost. The meter is mainly responsive to the surface area of the herbage and hence it is less sensitive to variations in moisture content of the pasture than previous meters. Thus it can be calibrated to measure the mass of herbage dry matter to ground level and reduces the need to collect and dry herbage samples for frequent recalibration ofthe instrument.

Spatio-temporal modelling of biomass of intensively grazed perennial dairy pastures using multispectral remote sensing

“…Traditionally, pasture biomass information in dairy paddocks was collected using pasture cuts (Cayley and Bird, 1996) visual assessments (Haydock and Shaw, 1975;Stockdale, 1984a), rising plate metre (Lile et al, 2001;Stockdale, 1984b;Thomson et al, 2001) and capacitance metre (Tucker, 1980;Vickery et al, 1980). Many farmers in New Zealand use visual assessment or RPM to make pasture biomass estimates and RPM gives reliable estimates of pasture biomass when at least 50 readings per paddock are taken in paddocks where average herbage mass is in the range between 1000 and 4000 kg DM ha −1 (Lile et al, 2001).…”

Métodos de avaliação de massa de forragem em pastagens de capim-estrela submetidas a intensidades de pastejo

“…Dentre os métodos indiretos, estão a altura comprimida do relvado, utilizando-se o disco medidor de forragem (DMF) (disk meter) (CASTLE, 1976), denominado por igual de prato ascendente (rising plate meter), a altura não comprimida do dossel com o uso da régua (SHAW et al, 1976), o bastão graduado (BG) (sward stick) (BARTHRAM, 1986), a estimativa visual e o medidor de capacitância (MC) (pasture probe ou sonda eletrônica) (VICKERY et al, 1980). Os métodos indiretos também exigem o corte de amostras de forragem, porém em números mais reduzido e não necessariamente realizadas em locais de outras avaliações, tornam as amostragens de MF mais funcionais e ágeis, viabilizando a utilização em pastagens com áreas extensas.…”

Methodology Comparison for Effective LAI Retrieving Based on Digital Hemispherical Photograph in Rice Canopy

“…Indirect methods for determining LAI are now commonly used to overcome this problem [5,6] and have an additional advantage of being non-destructive. These methods include direct measurement of intercepted radiation using line quantum sensors [7] or radiometers, inclined point quadrant [8], gap fraction techniques [3,5] and capacitance sensors [9]. Of these techniques, it is the group based on gap fraction data that is now the most widely applied.…”