Incorporating a periodic function into an equation for estimating herbage mass in Zoysia-dominated pastures from rising plate readings

Shiro Itano, Hajime Tomimatsu, Koji Nakagami, Yasuyuki Maeda

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A rising plate meter (RPM), which enables rapid, non-destructive estimation of herbage mass of pastures, is useful in grazing management. Herbage mass is estimated from the RPM readings using a linear regression model, which has the parameters α (constant) and β (slope). In this study, we analyzed the seasonal changes in the two parameter values for total and green herbage (TH and GH, respectively) masses in Zoysia-dominated pastures, and examined the potential for incorporating a periodic function (PF) of the parameters into the equation for estimating herbage mass. The values of both α and β showed a weak seasonal periodicity for TH. No periodicity and a clear seasonal periodicity were detected in the α and β values for GH, respectively. Compared with the linear regression models developed separately for individual dates, the equation incorporating a PF for β improved the estimation accuracy for the GH mass (from 0.64 to 0.77 as R2), though it did not affect the predictability for the TH mass. Incorporation of a PF into the model relating herbage mass to the RPM reading increases the sample number and broadens the data range by allowing the use of all seasonal data, and produces a single equation useful for estimating herbage mass across seasons.

Original languageEnglish
Pages (from-to)127-132
Number of pages6
JournalGrassland Science
Volume58
Issue number3
DOIs
Publication statusPublished - 2012 Sep 1
Externally publishedYes

Keywords

  • Green mass
  • Herbage mass
  • Periodic function model
  • Rising plate meter
  • Zoysia-dominated pastures

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Agronomy and Crop Science
  • Plant Science

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