The use of a rising plate meter to evaluate lucerne (Medicago sativa L.) height as an important agronomic trait enabling yield estimation

Abstract

A rising plate meter (RPM) is an instrument used for the measurement of compressed sward height and estimation of yield on grasslands. The aim of this study was to investigate the use of an RPM to evaluate lucerne height as an agronomic trait enabling yield estimation. Compressed height (CH), stem length, plant and stem density and yield measurements were recorded from the late‐vegetative stage to flowering in the first cut and from the late‐bud stage to flowering in the second and third cuts, during three successive years. For lucerne maximal stem‐length prediction, CH could be used successfully (with R 2 over 0·90) in developmental stages before flowering and for stem lengths up to 80 cm, irrespective of stand density or order of cut. The dry‐matter yield of lucerne was better predicted using CH (R 2 = 0·72) than maximal stem length (MSL) (R 2 = 0·53). The recommended number of observations was 7–9 per treatment in the first cut and twice this in subsequent cuts because of higher variability in stand structure. The use of RPM to measure CH of lucerne is not recommended when MSL exceeds 80 cm, or in the case of lodging. RPM may also be suitable for similar forage crops with erect or semi‐erect stems, subject to consideration of disc weight and diameter. Heavy discs are unsuitable for lucerne height prediction but could be more suitable for yield prediction.

Do sheep grazing patterns affect ecosystem functioning in steppe grassland ecosystems in Inner Mongolia?

“…The biomass was quantified five times by measuring height in each grid point with a 20 cm diameter rising plate meter (GRASTEC) (the diameter is 20 cm) and a mean value was calculated for that point. A calibration equation (1) was used to quantify the linear relationship between aboveground standing biomass (g DM/m 2 ) and sward height (H) (Schönbach et al, 2008;Hakl et al, 2012). The semivariograms show the heterogeneity of vegetation under different grazing intensity in two systems (Fig.…”

Differences in the crude protein fractions of lucerne leaves and stems under different stand structures

“…The average plant density of the stand reached about 60 plants m −2 . Average values of stand traits (Table ) were within the typical ranges previously obtained for 3‐ to 5‐year‐old lucerne stands (Hakl et al ., 2012b).…”

“…Our results suggest that stand traits make an important contribution, accounting for about 75% of CP fraction variability. Above all, MSL is a variable that can be easily assessed for individual plants or estimated from the compressed height of a lucerne stand as measured using a rising plate meter (Hakl et al ., 2012b). This variable also has a strong negative correlation with LWR (see Figure ), which is assessed less easily than MSL.…”

Comparing mobile and static assessment of biomass in heterogeneous grassland with a multi-sensor system

“…Swards of the latter two stocking rates showed similar USH levels in both years, although pastures were managed and monitored by the use of a compressed sward height meter (CSH; according Castle, 1976), maintaining levels at 6 cm (moderate), 12 cm (lenient) and 18 cm (very lenient) (Wrage et al, 2012). This disparity may indicate the influence of sward structure on the conducted measurement methods: while CSH reflects the resistance of biomass according to stem density and sward height (Hakl et al, 2012), USH predominantly detects protruding objects regardless of other sward conditions in subordinate layers (Fricke et al, 2011). This fact indicates the limitations of biomass predictions based on pure USH, as it may not directly reflect the biomass, particularly if swards are composed by plants of varying phenology, which is common in leniently grazed swards (Rook and Tallowin, 2003;Wrage et al, 2011).…”