A Flotation Method for Determining Root Mass in Soil¹

Abstract

Root weight is commonly determined as a criterion of root response to the environment. Determination of root weight by soaking soil and associated roots, and washing over sieves may result in losses of root material. In this study the distribution of cotton roots with depth and time was determined by soaking soil and roots in a solution containing 40 g/liter sodiumhexametaphosphate in a 1:5 soil solution ratio. The density of the resulting soil suspension was increased to 1.5 g/cm3 by adding dry, 78% pure CaCl2 in a ratio of 1 g CaCl2 to 2 g soil suspension. Roots floated to the surface and were skimmed from the surface with a fine wire strainer. By subsequent washing in tap water roots and organic debris ,were separated. Distributions of fine roots (mean diameter 0.25 mm) and total root mass for field grown cotton is shown at various times and depths.

Leaf area and transpiration efficiency during different growth stages in oats

“…The shape of the IT/ET p curve in Fig. 5 is almost identical to the one published by Al-Khafaf et al (1978) for cotton. From Figs 5 and 6 it is evident that, at < 3-4, LAI increased normalized IT and T (broken curve in Fig.…”

Arid site water balance: evapotranspiration modeling and measurements

“…Soil collected from each split-tube sample was returned to the lab to determine gravimetric water and root content. Roots were extracted from the soil using a flotation screening process, described by Al-Khafaf, Wierenga and Williams (1977), that uses a dispersant and salt mixture to float off organic material.…”