Soil texture
What is it?
determine soil texture. There is no good, or bad
value for soil texture. All soil textures, sandy, silty
and clayey, have advantages and disadvantages.
Write the soil texture on the Bullseye Score Card.
Soil texture is determined by the proportion of
sand, silt and clay it contains. A soil sample will
either feel gritty, silky or smooth depending on
the relative quantity of those components.
Measuring method:
Why it is important:
Soil texture needs to be assessed only once at
each monitoring site. Use a spade to take a sample
from halfway along the transect, between two
grass plants. A large golf-ball sized amount of soil
from 5-10cm deep is enough. Use this sample to
carry out the Ribbon Test shown on the next page.
Texture strongly influences a number of soil
properties including structure, water infiltration
and water holding capacity. Texture does not
readily change as it is an inherent property of the
soil. A soil’s texture depends mainly on the type
of rock from which it was formed. Soil texture is a
key characteristic of any land type.
Equipment:
How to assess it:
Soil texture is assessed by the Ribbon Test – which
is the way a soil behaves when a small handful of
soil is moistened and rolled into a bolus (ball) in the
palm of the hand. This bolus is then pressed out
between thumb and forefinger to form a ribbon.
The strength and feel of the bolus and the length
of the ribbon formed are rated against a chart to
Spade, water bottle, water, ruler, rag or paper
towel, mortar and pestle, RASH Manual.
Soil texture only needs to be assessed once
at each monitoring site. It is an inherent
property of the soil and will not change –
determining texture is not a soil health test.
Soil texture table
Evaluate samples against this table for bolus coherence, feel and ribbon length.
1 2 3 4 5 6
Bolus
coherence Feel Approx.
ribbon length Soil texture
type Comments Approx. %
clay content
Nil to slight Sandy and gritty Less than
15mm Sand Unable to form a ball, single
grains stick to fingers Up to 10%
Slight to just
firm Sandy 15-25mm Sandy loam Sand grains can be seen or
felt 10-25%
Loams Can feel spongy or silky, no
sand can be felt 20-30%
Firm
Smooth, spongy Approx. 25mm
and may be greasy
Firm to
strong Sandy 25-40mm Sandy clay
loam Sandy to touch with grains
visible 20-30%
Firm to
strong Smooth 40-50mm Clay loam Smooth to touch 30-35%
Strong
plastic bolus Plastic 50-85mm Light clay Smooth like soft plasticine 35-45%
Strong
plastic bolus Plastic Greater than
85mm Medium –
heavy clays Smooth and handles like
plasticine Over 45%
10 - RASH MANUAL