One essential requirement for an increase in the efficiency of pastoral grazing management in New Zealand is the development of a quick, reliable, and objective method for assessing pasture bulk. The traditional method for estimating biomass entails harvesting and dry-weighing sample quadrats, then extrapolating from the sample to the paddock. This is labour-intensive and slow, so we seek a means of 'remote weighing' of the pasture using optical remote sensing techniques. Field trials in the Waikato region (latitude 38ºS) of New Zealand have demonstrated that measuring pasture reflectance in three wavelength bands (near-infrared, red, green) permits us to retrieve green biomass to within an average root-mean square error of 260 kg / ha, for pasture green-bulk ranging from 70 to 4000 kg / ha, using a three-band regression. We find that the usual remote measure of greenness, NDVI (normalized difference vegetation index), saturates at moderate pasture densities, so is not useful in the New Zealand pastoral context. We have been able to confirm the field results with a pasture canopy radiance model which takes into account the effects of layering and variable live / dead fraction.adequately represent the density variations present within the paddock. And because pasture production varies with season, this sampling exercise needs to be repeated throughout the year in order to capture the seasonal changes.The direct method is tedious, labour intensive, and slow. A further disadvantage is that the total dry-matter, as an unsorted mix of green and dead, needs care when it comes to estimating feed value, since both fractions vary with season. In the Waikato, a moist temperate region, it is the green fraction of the normal pasture that provides the overwhelming proportion of the ruminant diet. What is needed is a quick and accurate method for estimating pasture biomass; the ideal method would be stable across seasons and farming zones, and would not demand a high labour input. In essence, we seek a means of 'remote weighing' of the pasture.One early attempt at remote weighing was the 'pasture capacitor', an ingenious device which treats the pasture biomass as a dielectric material which alters the capacitance between the conducting probes of a physically large capacitor. Essentially this device responds to the wet biomass, so seasonal adjustments to its calibration were found to be necessary as the moisture content of pasture vegetation varies with season and live/dead ratio. For example, plant moisture content for Waikato pastures might rise from ~70% in summer to ~85% in early winter.This experience allows us to tighten our specification of the 'ideal' pasture biomass-meter: the device should be insensitive to plant moisture, thus permitting the remote dry weighing of pasture. Further, if our primary interest is the reliable estimation of nutritional feed availability for the grazing animal, then the device should report the weight