Determination of Pasture Biomass Using Four Indirect Methods

Abstract

The most accurate method for determining canopy biomass of pastures for forage availability is by cutting and weighing forage from known areas. Faster methods that require less time and labor would help producers to monitor forage availability in pastures on a daily or weekly basis. Indirect methods rely on calibrations performed on pure or evenly distributed plant compositions to determine forage biomass. However, microclimates developed by varying landscape positions and soil morphological characteristics of pastures may cause uneven plant and species distributions. This study was performed to compare the ability of a modified Robel pole, rising plate meter, canopy height stick, and Li‐Cor LAI 2000 leaf canopy analyzer to determine forage availability in pastures with varying species composition from four areas. Swards consisted of pure warm‐season grass stands, cool‐season grass stands, legume stands, and grass‐legume mixtures. Instrument readings were compared with forage availability determined by clipping and were measured for accuracy, or closeness to clipped weight. For all observations, coefficients of determination (r2), were 0.63, 0.59, 0.55, and 0.32 for the modified Robel pole, rising plate meter, canopy height stick, and leaf canopy analyzer, respectively. For modified Robel pole readings, r2 was highest for observations in red clover (Trifolium pratense L.) (r2 = 0.83), smooth bromegrass (Bromus inermis Leyss.) (r2 = 0.82), and alfalfa (Medicago sativa L. (r2 = 0.76) swards, whereas the rising plate meter r2 values were highest for observations in tall fescue (Festuca arundinacea Schreb.) (r2 = 0.85), alfalfa (r2 = 0.84), and red clover (r2 = 0.73) swards. Grass observations also had their highest r2 values with the modified Robel pole and rising plate meter at 0.63 and 0.59, respectively. The modified Robel pole proved to be the most accurate method used over a variety of species.

Distinguishing Intensity Levels of Grassland Fertilization Using Vegetation Indices

“…We assume that this was caused by small differences in canopy biomass occurring at this stage. This is supported by measurements of Compressed Sward Height (CSH), which are highly correlated to canopy biomass [49]. (Table A2) (Table A2).…”

Effects of nitrogen fertilization on biomass yield and quality in large fields of established switchgrass in southern Iowa, USA

“…In 1998 and 1999, canopy height was measured at harvest for each landscape position using a modified rising plate meter [11]. The rising plate meter consisted of a 0.929 m 2 plexi-glass plate with a 1.3 cm hole in its center, through which a 1.3 cm electric aluminum tube marked at 1 cm intervals was inserted.…”

Integration of Optical and X-Band Radar Data for Pasture Biomass Estimation in an Open Savannah Woodland

“…Pastures play an important role in rangeland ecology, ecosystem services, and livestock-related industries [2]. Physical sampling of pasture biomass over large areas is not generally considered feasible in rangeland and savannah systems; it is not possible to collect and collate sufficient field data to adequately inform land managers and provide sufficient input for pasture biomass modelling [3]. A major issue is the estimation of pasture biomass for livestock forage budgeting and conservation purposes [4].…”