Soil Characterisation

Table of Contents

1.0 Soil: An Introduction................................................................. 1

1.1 Soil Formation.................................................................2

1.2 Soil Profile......................................................................5

1.3 Soil Composition..............................................................7

1.4 Physical Properties of Soil....................................................9

1.5 Chemical Properties of Soil...................................................11

1.6 Soil Macro and Micronutrients................................................13

2.0 References..................................................................................20

2.1 Book and Journal.....................................................................20

2.2 Internet.................................................................................21

Appendix A

List of Figures

Figure 1.1 Soil Interface...................................................................1

Figure 1.2 Water Table........................................................................5

Figure 1.3 Soil Profile.........................................................................6

Figure 1.4 Soil Composition..................................................................7

Figure 1.5 Soil Structure.......................................................................10

Figure 1.6 Flocculation and Aggregation Formation.................................... 11

Figure 1.7 Nutrient Availability............................................................12

Figure 1.8 Nitrogen Cycle....................................................................15

Figure 1.9 Phosphorous Cycle...............................................................16

Figure 1.10 Micronutrient Availability......................................................18

List of Tables

Table 1.1 Properties of Soil Solids.......................................................9

Table 1.2 Plant Available Form of Micronutrient......................................18

Table 1.3 Micronutrient Fertilizer Forms and Application...........................19

1.0 Soil: An Introduction.

The soil or the pedosphere is the uppermost layer of the Earths crust that is inhabited by living organisms [1]. Soil is the collection of natural bodies occupying portions of the Earth's surface that support plants and that have properties due to the integrated effects of climate and living matter acting upon parent material, as conditioned by relief, over periods of time [2]. Soil however is not merely the sum of minerals, organic matter, water and air but is the interface zone where the atmosphere, the hydrosphere, the biosphere and the geosphere all meet and it owes its existence to the interactions that occur between the spheres. It is these dynamic reactions which contribute to the multiple functions which soils perform, which include supporting plant life and life within the soil, biogeochemical cycling of elements, energy cycles, water storage and exchange and ecosystem productivity. Soil can be considered a non-renewable natural resource because it develops over a very long timescale [3].

Fig. 1.1 Soil Interface [14]

1.1 Soil Formation

There are a number of factors which influence soil formation and development. They are,

§ climate

§ parent material

§ living organisms

§ topography

§ time

§ water table

Climate

Climate is the most important factor influencing soil formation. This is so because, in addition to its direct influence on parent material weathering and soil development, it is largely responsible for variation in plant and animal life. Its influence overrides that of the other factors. Rainfall and air temperature are the most important climatic criteria. On the basis of these, the world can be divided into climatic regions or zones. Each climatic region contains a range of soils specific to it. Ireland's climate is dominated by low air temperature and evaporation rate. As a result, rainfall exceeds evaporation and most soils tend to be leached of bases. This makes them acid, requiring regular liming and fertilizer addition. Regional variation in rainfall and evaporation is reflected in soil type variation [4].

Parent Material

Soil is developed from the underlying material (the "parent material ") by a weathering and ageing process. The nature of the parent material and of the weathering and ageing process strongly influences the properties and usefulness of individual soils. Parent materials are classified as residual, transported or cumulose.

Residual materials are rock deposits which weather in situ long enough for soils to develop from them. Transported materials are broken-down rock which has been transported some distance by natural forces such as wind, water, ice or gravity. Soil then develops from these transported materials in their new locations. This is the most important of parent material classes as it includes all material moved by water (such as alluvium, colluvium, lacrustine