A Comparison of Methods Used to Determine Biomass on Naturalized Swards

Abstract

An experiment was conducted in 2000 to compare simple visual estimate, sward height and rising plate meter (RPM) methods for determining forage biomass in mixed-species, naturalized, rotationally grazed dairy and beef pastures. Measurements were taken pre-and post-grazing on 10 sampling dates at the dairy pasture, and post-grazing at 13 sampling dates at the beef pasture. For each sampling date, the effectiveness of each method for estimating the actual biomass from a quadrat was evaluated using regression analysis. The results for the visual estimate method were not consistent, with non-linear relationships occurring early and late in the season. While the meter stick was most effective in the dairy pasture, the RPM was most effective in the beef pasture. Species composition and structural characteristics of the stand were important factors affecting accuracy of biomass estimation. Equations developed for each method and site using data from all dates had low R 2 -adjusted values, and were unreliable predictors of biomass. The results from individual sites and dates were extremely variable, with no single method effective in all circumstances. To estimate forage biomass in mixedspecies, naturalized pastures, standard quadrat harvesting remains the most reliable method, provided that enough quadrats are clipped to adequately represent a given area.

The importance of grasslands for animal production and other functions: a review on management and methodological progress in the tropics

“…Alternatives such as the pasture capacitance meter and the pasture plate meter or rising plate meter (Gourley and McGowan, 1991) have been developed, and in reasonably uniform stands of a single or two-species pastures these can be effective (Murphy et al, 1995;Martin et al, 2005). However, in tropical pastures, herbage mass was often overestimated by the indirect methods and revalidation was frequently necessary (Braga et al, 2009;Lopez-Guerrero et al, 2011).…”

Biophysical and economic water productivity of dual-purpose cattle farming

“…Rainfall data were obtained from the local meteorological station, which was located at a maximum distance of 7 km from farms. Forage biomass was determined by weighing plant samples harvested from each plot within a 1 m² quadrat at each harvest (Martin et al, 2005). Subsequently, the nutrients (net energy and digestible protein) supplied by this biomass were estimated.…”

Developing in situ Non-Destructive Estimates of Crop Biomass to Address Issues of Scale in Remote Sensing

“…In addition, with a high density of biomass estimates generated by these techniques, transects can be made that account for uncertainties over heterogeneous canopies for remote sensing applications [12]. Reviews of in situ non-spectral methods pertaining to crops and rangelands can be found in [13][14][15]. These techniques involve: visual assessment (e.g., [16]), crop height (H) (e.g., [17]), fraction of absorbed photosynthetically active radiation (FAPAR) derived from a ceptometer, fraction of vegetation cover (FVC) derived from red-green-blue (RGB) band photographs (e.g., [18]), electronic capacitance probes (e.g., [19]), weighted discs (e.g., [20]) or pendulum sensors (e.g., [21]).…”