Seasonal Variation in the Rising Plate Meter Calibration for Forage Mass

Abstract

Measurement of forage mass is critical to the management of forage allowance in grazing systems. Th e rising plate meter (RPM) was developed to monitor forage mass quickly and easily; however, it must be calibrated to provide reliable calculations of forage mass and the calibration coeffi cients may vary across seasons. Our objective was to investigate seasonal patterns in calibrations of the RPM for estimating forage mass in six cool-season grass swards in Ohio. Th e RPM reading was highly signifi cant (P < 0.01) in explaining variation in forage mass across sites and weeks; however, the RPM × week, RPM × site, and RPM × week × site interactions (P < 0.01) for forage mass indicated the relationship between RPM reading and forage mass varied among sites and over time. At one site, the RPM to forage mass relationship was investigated for three cool-season grass species, but the RPM × species and RPM × week × species interactions were not signifi cant (P > 0.05). Although there was variation among and within sites for the slope coeffi cients of forage mass regressed on RPM reading, a broadly similar seasonal pattern was found at most sites. Th e slope coeffi cients were usually high in early spring, decreased rapidly during the fi rst weeks of the growing season, and then increased from early summer to the autumn. We concluded the RPM should be calibrated at least monthly over the growing season to defi ne the seasonal pattern and changes in the slope coeffi cients for forage mass regressed on RPM readings.

Improving pooled calibration of a rising‐plate meter for estimating herbage mass over a season in cool‐season grass pasture

“…() reported for Zoysia ‐dominated pasture in Japan, but the asymmetric pattern as Ferraro et al . () reported in cool‐season grasses in the USA. The intercept coefficients showed seasonal pattern opposite to that shown by slope coefficients and a strong inverse correlation with them ( r = −0·89, P < 0·001, n = 86).…”

“…However, the method has a disadvantage of inaccuracy because it ignores seasonal variations in the relationship between RPM reading and herbage mass (e.g. Martin et al ., ; Braga et al ., ; Ferraro et al ., ). The third one has been developed as an intermediate method of the first two (L'Huillier and Thomson, ) and established by RPM manufacturers or advisers (Ferraro et al ., ).…”

“…However, the periodic function is unlikely to fit to asymmetric seasonal changes in the calibration parameters for cool‐season grasses, as Ferraro et al . () noted. Therefore, the objectives of this study were (i) to confirm the seasonal trend in the parameters of the calibration of RPM for estimating herbage mass for cool‐season grass in Japan and (ii) to construct a new calibration method that considers the seasonal pattern in RPM calibrations, applicable to cool‐season pastures.…”

Effects of sites and years on the coefficients of rising plate meter calibration under varying coefficient models

“…The former would be attributed to the accumulation of dead residue caused by the management in the previous season (Braga et al 2009;Ferraro et al 2012;Nakagami and Itano 2014) and the latter to the management practice and the meteorological condition affecting the dead-material content after the reproductive stage.…”

Evaluation of a Rising Plate Meter for Use in Multispecies Swards

“…Forage measurements allow producers to determine appropriate forage allowance for optimal animal performance and to reduce feed costs (Ferraro et al, 2012). In pasture-based dairy systems, accurate budgeting of available forage is crucial to maintaining milk production while maximizing limited pasture resources.…”