Estimating Root Length Density by the Core-Break Method
1989
Bland, William L.
Rapid and accurate methods of measuring root length density (RLD, cm root cm⁻³ soil) are needed for verifying growth predictions and assessing genotypic differences. The core-break technique, in which the number of roots visible at a broken cross section of a soil core is used to estimate rooting, was evaluated as a means of measuring RLD. Root systems of wheat, Triticum aestivum L., cotton, Gossypium hirsutum L., and sorghum, Sorghum bicolor (L.) Moench, were sampled and core-break root counts regressed on RLD measured in the same soil core. Linear relationships were obtained between counts and RLD for each crop on each day of sampling. Calibration equations were derived from regressions of all data for a species. Prediction intervals (90%) for an estimate of RLD from the mean of several core-break counts were about ± 0.3 cm⁻² for wheat, ±0.2 cm⁻² for cotton, and ±0.8 cm⁻² for sorghum. The core-break method yields only a low-precision estimate of RLD from the mean of several core counts, even if calibrated for the soil and crop combination of interest.
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