Upper layer of earth

1. WHAT IS SOIL?
The upper layer of earth in which
plants grow, a black or dark brown
material typically consisting of a
mixture of organic remains, clay,
and rock particles

2. Physical properties of soil
1. Soil Texture
 Texture refers to the relative proportions of
particles of various sizes such as sand, silt
and clay in the soil
 Sand particles are the largest and clay
particles the smallest
 Most soils are a combination of the three.
The relative percentages of sand, silt, and
clay are what give soil its texture


3.  A clay loam texture soil, for example, has nearly
equal parts of sand, slit, and clay

4. Soil Structure
 Soil structure is the arrangement of soil
particles into small clumps, called peds
or aggregates
 Soil particles (sand, silt, clay and even
organic matter) bind together to form
peds
 Depending on the composition and on
the conditions in which the peds formed
the ped has a specific shape

5.  They could be granular (like
gardening soil), blocky, columnar,
platy, massive (like modeling clay)
or single-grained (like beach sand)

6. SOIL COLOR
 Soil color is influenced primarily by soil
mineralogy – telling us what is in a
specific soil
 Soils high in iron are deep orange-
brown to yellowish-brown
 Those soils that are high in organic
matter are dark brown or black


7.  Color can also tell us
how a soil “behaves” –
a soil that drains well is
brightly colored and
one that is often wet
will have a mottled
pattern of grays, reds,
and yellows

8. Chemical properties of soil
 Soil chemical properties including pH,
electrical conductivity (EC), cation
exchange capacity (CEC), C/N ratio of
added amendment, and organic matter
(OM) content can impact soil N supply

9. Acidity (pH)
 Acidity (pH) is a measure of the concentration
of free hydrogen ions (H+)
 A high concentration in the soil signifies a low
pH, whilst a low concentration equals a high
pH
 Soils and other substances with a pH below 6
are called acidic, whilst those with a pH above
6 are known as base or alkaline

10. Salt levels
 The salt level is the sum of all the mineral salts
that are present in the soil
 They can originate from the soil itself, fertilizer,
organic manure and in coastal areas from salt
marshes or tidal marshes.

11. CEC
 CEC is the abbreviation of cation exchange
capacity, which notes the amount of cations can
be bound to the soil
 These cations are mainly Ca2+, Mg2+, K+, Na+
and to a lesser extent NH4+ , Al3+, Fe2+, Mn2+
and H+

13. Macro-elements
 Macro-elements are the most important nutrients for
plants
 They occur naturally in the soil to some extent and
can be supplemented with fertilizers, manure and
compost
 The macro-elements are calcium (Ca), magnesium
(Mg), potassium (K), Sulphur (S), phosphate (P),
nitrogen (N), sodium (Na)

14. Micro-elements
 Trace elements are nutrients that plants
need in small doses
 The trace elements are boron (B),
copper (Cu), manganese (Mn), cobalt
(Co), silicon (Si), zinc (Zn), iron (Fe) and
molybdenum (Mo)