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Uses and capabilities of electronic capacitance instruments for estimating standing herbage

Posted date: November 17, 2016
Publication Year: 
1973
Authors: Currie, P. O.; Morris, M. J.; Neal, D. L.
Publication Series: 
Scientific Journal (JRNL)
Source: Grass and Forage Science. 28: 155-160.

Abstract

An electronic capacitance meter was used to estimate herbage yield from sown ranges in western USA. On an area in Arizona where the grass stand had been sown broadcast, ^a r2 of 0-47 was obtained between the meter value and oven-dry weight estimate. Excluding those plots with very large amounts of standing dead organic matter (OM), or very succulent plants which bad not been sown, improved yield estimates. Tests on pastures in Colorado in which seed had been drilled and the meter tested to evaluate performance in relation to drill rows showed that a common regression could be used for estimating yield. Methods of placing the meter in relation to row directions are described which avoid a biased estimate of total pasture yield. Cutting the herbage in a 3-dimensional manner improved the r2 values over those obtained by the usual 2-dimensional cutting procedure. Separation of dead OM from living plant material did not significantly change the r2 values and showed that dead OM bad very little influence on the meter reading. This dead OM can contribute significantly to variation of the estimate about the regression line, however, and if differences in dead OM are substantial, sample sizes may need to be increased or sampling stratified to obtain an accurate yield estimate. Pertinent literature on the evolution of electronic capacitance instruments for estimating herbage yields bas been presented in Part 1 of this series (3). The present evaluation is restricted to the herbage yield estimates from mechanically sown pastures. The Neal Electronics Model 18-612 meter was used to make the yield estimates.

Citation

Currie, P. O.; Morris, M. J.; Neal, D. L. 1973. Uses and capabilities of electronic capacitance instruments for estimating standing herbage. Grass and Forage Science. 28: 155-160.