## 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 R^{2}), 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 language | English |
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Pages (from-to) | 127-132 |

Number of pages | 6 |

Journal | Grassland Science |

Volume | 58 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2012 Sep 1 |

Externally published | Yes |

## 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