Module 1

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What is soil?

Soil is a mixture of minerals, dead and living organisms, organic materials, air and water.

What ecosystem services do soils perform?

• Provisioning

  • e.g. provide food, medicine, water.

• Regulating

  • e.g. processes that purify water, decompose wastes, control pests, or modify atmospheric gases.

• Supportive

  • e.g. assisting with nutrient cycling, seed dispersal, primary biomass production.

• Cultural

  • e.g. providing spiritual uplift, scenic views, and outdoor recreation opportunities.

What are the key functions of soil?

• Supports plant growth 

• Regulates water supplies 

• Controls exchanges of gas and heat 

• Acts as habitat

• Acts as an engineering medium 

• Acts as a recycling system

What are the three soil phases?

• Solid phase

  • Mineral phase

• Liquid phase

• Gaseous phase

What is the solid phase of soil?

The solid phase consists of mineral particles, organic matter (plant roots and residue), and soil microorganisms that provide structure and nutrients necessary for plant growth.

*also carbonaceous remains and stable end products of decomposition

What is the liquid phase of soil?

The liquid phase (soil solution) consists of water and dissolved nutrients, which are essential for plant uptake, respiration and biochemical processes within the soil.

Soil water is held within pores where the attraction between water and the surfaces of soil particles greatly restricts ability of water flow.

Soil saturation

Occurs when all the pore spaces within the soil are filled with water, leaving no room for air.

Field capacity

The amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in previous soils of uniform structure and texture. 

Permanent wilting point

May be defined as the amount of water per unit weight or per unit soil bulk volume in the soil, expressed in percent, that is held so tightly by the soil matrix that roots cannot absorb this water and a plant will wilt.

What problems arise when a soil contains too much water?

• Water logging (induces anoxic conditions)

• Root rot

• Rapid contaminant dispersion

• Leaching of minerals and nutrients

What is the gaseous phase of soil?

The gaseous phase is dependent on the soil pore system and contains gases such as N₂, O₂, and CO₂. O₂ is critical for plant roots and microbial respiration.

This phase has an inverse relationship with the liquid phase (as gas ↑ liquid ↓).

How do plants obtain nutrients?

To be taken by a plant, the nutrient element must be in a soluble form and must be located at the root surface. There are three principle mechanisms of nutrient uptake. All three mechanisms may operate simultaneously but one mechanism or another may be most important for a particular nutrient.

What are the three principle mechanisms of nutrient uptake?

• Root interception - growth of (root hairs) into new area 

• Mass flow – dissolved nutrient carried with water

• Diffusion – concentration gradient

How do soils form?

Soil formation is stimulated by climate and living organisms acting on parent materials over periods of time and under the modifying influence of topography.

e.g. bare rock and deposited material after landslides, floods, eruptions and retreated glaciers

What are the major environmental factors that control soil formation?

• Climate (cl)

• Organisms (o)

• Relief or topography (r)

• Parent materials (p)

• Time (t)

*Si = f × (cl,o,r,p,t)

Climate (as a soil forming factor)

• Affects the rates of chemical, physical, and biological processes through:

  • Effective precipitation (rainfall)

  • Temperature 

• Seasonal rainfall distribution, evaporative demand, site topography and soil permeability interact to determine how effectively precipitation can influence soil formation 

• For every 10°C rise in temp, the rate of biochemical reactions double 

• Temperature and moisture influence SOM content by affecting the balance between plant growth and microbial decomposition

Organism ( as a soil formation factor)

• Organic matter accumulation, biochemical weathering, profile mixing, nutrient cycling, and aggregate stability are all enhanced by the activities of organisms in the soil 

• They comprise of vegetation, macro- and meso-fauna and microorganisms 

• Organisms act by physical alteration, chemical alteration/carbon addition, and translocation of soil particles  

• In natural vegetation, cation cycling by trees and heterogeneity in rangelands (grasslands, shrublands, woodlands, wetlands and deserts) alter soil formation 

• Invertebrates impact soil structure and particle rearrangement by building channels in the soil, building structure and porosity as well as redistributing minerals  

• Human influence is considered the sixth factor in soil formation due to land use change, land management, land degradation, soil sealing (roads) and mining  

Relief (as a soil formation factor)

• Refers to the configuration of the land surface 

• Topography governs and is shaped by water movement

• The landscape controls the deposition and accumulation of material and soil profile layering and depth

  • e.g. shallow profile and deep soil profile

Parent material (as a soil formation factor)

• Igneous – solidification of molten material (magmatic origin) 

  • e.g. granite, basalt

• Sedimentary – solidified deposited material 

  • e.g. limestone, shale, sandstone

• Metamorphic – igneous or sedimentary material altered by heat and pressure 

  • e.g. marble, gneiss, slate and quartz 

• Differ in hardness and susceptibility to weathering 

Time (as a soil formation factor)

• Soil-forming processes take time 

• The weathering of rock generally creates 0.01-0.1 mm of new soil per year 

• The rock weathering into soil material tend to be greatest for the thinnest soils on steep slopes and rates as high 2 mm/year have been measured on steep mountains in high rainfall tropical areas

Weathering

A biochemical process that involves both destruction and synthesis. The original rocks and minerals are destroyed by both physical disintegration and chemical decomposition.

Physical weathering

Influenced by temperature, abrasion by water, ice and wind, and plant and animals 

Factors of biochemical weathering

• Hydration

  • water molecules may bind to minerals in soil 

• Hydrolysis

  • water molecules split into their hydrogen and hydroxyl components

  • the hydrogen often replaces a cation from the mineral structure 

• Dissolution

  • water is capable of dissolving many minerals by hydrating the cations and anions until they become dissociated from each other 

• Acid reactions

  • weathering is accelerated by the presence of acids, which increase the activity of hydrogen ions in water 

• Oxidation-reduction

  • occurring mostly in minerals that contain iron, manganese, or sulfur 

• Complexion

  • formation of organic complexes (e.g. metals with humic acid) 

What are the four basic processes of soil formation?

• Transformations

  • occur when soil constituents are chemically or physically modified or destroyed, and others are synthesized from the precursor materials 

• Translocations

  • involve the movement of inorganic and organic materials laterally within a horizon or vertically from one horizon up or down to another 

• Additions

  • inputs of materials to the developing soil profile from outside sources 

• Losses

  • materials lost from the soil profile by leaching to groundwater, erosion of surface materials and volatilisation of gases  

What are the main soil forming factors in Australia?

The main factors are wind and water. Other factors include:

• Physical weathering

  • freeze and thaw (temperature), eluviation/illuviation of clay (movement), abrasion, fragmentation.

• Chemical weathering

  • dissolution/precipitation, salinisation, leaching, calcification/decalcification, podsolisation. 

• Biological weathering

  • e.g. termites, ants, earthworms, burrowing animals.

The master horizons and layers

Six master soil horizons are commonly recognised and are designated using the capital letters O, A, E, B, C, and R.

Upper layers have been changed the most, while the deepest layers are most similar to the original regolith (soil’s original parent material).

O horizons

• Organic horizons that generally form above the mineral soil or occur in an organic soil profile 

  • Derived from dead plant and decomposed animal residues 

  • O horizons occur in forested areas  

  • Generally absent in grassland regions

A horizons

• The topmost mineral horizons, generally contain enough partially decomposed organic matter to give the soil a colour darker than that of lower horizons.

  • In medium-textured soils, A horizons are often coarser in texture having lost some of the finer materials by translocation to lower horizons and by erosion.

E horizons

• Zones of maximum leaching or eluviation of clay, iron, and aluminum oxides, which leaves a concentration of resistant minerals (such as quartz) in sand and silt sizes.

  • E horizon is usually lighter in colour

  • Quite common in soils developed under forests 

  • They rarely occur in soils developed under grasslands

B horizons

• Layer where materials have accumulated, typically translation or leaching from the horizons above.

  • In humid regions, B horizons are the layers of maximum accumulation of materials such as iron and aluminum oxides and silicate clays (Bt)

  • In arid and semiarid regions, calcium carbonate or calcium sulfate may accumulate

C horizons

• Unconsolidated material underlying the solum (A and B horizons), below zones of biological activity and has not been sufficiently altered by soil forming processes.

  • In dry regions, carbonate and gypsum may be concentrated in the C horizon.

R horizon

• Layer comprised of consolidated rock, with little evidence of weathering.

What characteristics allow us to identify soil layers?

• Soil (matrix) colour 

• Redoximorphic features 

• Texture 

• Coarse fragments 

• Artefacts 

• Bulk density 

• Structure 

• Coatings and bridges 

• Cracks 

• Carbonates 

• Secondary carbonates 

• Secondary gypsum 

• Secondary silica 

• Cementation 

• Water saturation 

• Volcanic glasses 

• C_org content 

• Human alterations 

Anthroposol (soils resulting from human activities)

• Formed by modification, mixing, truncation or burial of the original soil or creation of new parent material.

  • Anthropic material must be > 0.3 m thick

  • Identified by the presence of artefacts

  • Sealed and semi-sealed surfaces are regarded as ‘non-soil’ (urban soils) 

    • e.g. streets, roads etc.

Organosol (organic soils)

• Dominated by organic matter, humus or peats.

  • Colder and wetter climates cause less oxidation and decomposition of organic matter resulting in peat swamps

  • Mainly southern Tasmania (uncommon in Australia).

Podosol (organic materials and aluminium, with or without iron)

• Characterised as B horizons dominated by the accumulation of organic matter (Bh), sesquioxides (Al/Fe) (Bs) or both (Bhs).

  • Bleached and sandy lower A horizon 

  • Mostly very permeable

  • Low fertility, poor water retention, waterlogging (some forms)

  • Requires vegetation (tree) cover 

  • Occurring in humid high rainfall areas.

Vertosol (shrink and swell clay soils)

• Clay soils that shrink and swell, and crack when dry, derived from basalt or alluvial deposits.

  • Good water holding capacity and fertility 

  • Self mulching 

  • Difficult to manage

    • High sodium in some cases

    • Excessive saturation and cracking can be a problem during storm season 

  • Limited to medium-low rainfall areas (around 600 mm)

  • Occurring in Queensland.

Hydrosol (wet soils)

• Soils that are seasonally or permanently saturated with water for at least 2-3 months in most years.

  • May or may not experience reduced conditions (indicated by grey/mottles) due to waterlogging or high groundwater table

  • Occurring in depressions and low-lying plains 

  • Mangrove swamps are borderline organosol or hydrosol.

Kurosol (acid soils with an abrupt increase in clay)

• Duplex soils with a distinct texture contrast between A and B horizons due to high amounts of leaching.

  • B horizon acidic (pH < 5.5) 

  • B horizon may be high in magnesium (magnesic), sodium (sodic) or aluminium 

  • Vegetation ranges from eucalypt woodland to forest (rainfall dependent).

  • Occurring in high rainfall regions.

Sodosol (high sodium soils, abrupt increase in clay)

• Soils that are sodic (high sodium content) and have a strong texture contrast between A and B horizon.

  • B horizon is sodic and clayey (dispersive and unstable) 

  • B horizon not acidic

  • Low agricultural potential due to poor structure, reduced permeability, and increased erodibility 

  • Mostly occurring in dry arid regions

  • Occurring in Victoria.

Chromosol (abrupt increase in clay)

• Soil with a strong texture contrast between A horizons and B horizons, where the subsoil is clayey and neither acidic or sodic.

  • Can be brightly coloured 

  • May have low internal drainage (due to clay content)

  • Red Chromosol occurring in NSW, Yellow Chromosol occurring in WA.

Calcarosol (soils with calcium carbonate)

• Soil with a high composition of calcium carbonate (lime or CaCO₃) in all or part of profile with gradual clay content with depth.

  • Shallow, low water retention, and wind erosion in sandier types 

  • High salinity, alkalinity and sodicity may be a problem (damaged soil structure)

  • Limited to low rainfall, arid areas

  • Occurring in SA.

Ferrosol (iron rich soils) 

• Soils that are rich in iron (>5% Fe in B horizon) and well-structured. 

  • May be degraded by erosion and compaction caused by tillage practices, may suffer from acidification 

  • Deep and well-drained, rapid infiltration and water movement

  • Good agricultural soil.

Dermosol (structured soils)

• Soils with a negligible texture contrast between A and B horizons but a well-developed soil structure in the subsoil.

  • Clay skins on peds 

  • Moderate to high fertility

  • Moderately deep and well drained (due to peds) in wetter regions.

Kandosol (Structureless soils)

• Soils with a negligible texture contrast between A and B horizons with a weakly structured subsoil (not many aggregates forming, mainly single grain soil).

  • Susceptible to crusting and hardening of soil surface 

  • May be brown, yellow or red 

  • Most have low fertility (grazing and native pastures) 

  • Occurring in NT.

Arenosol

• Soils with a sandy texture.

  • Deep sands (quartz) 

  • <15% clay 

  • Single grained

  • Occurring in WA.

Rudosol (minimal soil development)

• Soils with minimal pedological development (no profile development beyond the surface layer). 

  • Young soils (e.g. sediments)

  • Can vary widely in terms of texture and depth 

    • e.g. shallow or stony

  • Often stratified or highly saline 

  • Low fertility and water-holding capacity

  • Occurring in in desert and arid regions.

Tenosol (weakly developed soils)

• Soils with weak pedological development (more subsoil development than rudosols). 

  • Low fertility and water holding capacity.

What is the importance of soil organic matter?

• Adds soil moisture content

• Facilitates soil structure and compaction

• Contributes to soil nutrient status

• Facilitates cation exchange capacity

• Facilitates biological activity and energy storage

Effect of soil organic matter on soil structure

• Aggregate stability

  • Promotes the formation of stable soil aggregates

• Compaction

  • Particulate organic matter helps resist compaction

• Erosion

  • Aggregate stability helps reduce erosion

• Crusting

  • Helps reduce preconditions to crust formation (i.e. erosion and aggregate destruction)

Effect of soil organic matter on nutrient cycling

• Accept, hold and release cations

  • High cation exchange capacity of soil organic matter improves the ability to retain base cations

• Oxy-anion supply (N, P, S)

  • Organic N, P and S pool are source of plant available macronutrients via microbial mineralisation

Effect of soil organic matter on water regulation

• Infiltration and retention

  • Encourages stable and diverse pore structure to receive, store, and release moisture for plant use

• Water supply

  • Adequate water retention to buffer and reduce effects of drought

• Buffers extreme rainfall events

  • Encourages infiltration to reduce erosion and pooling in extreme rain event.

Effect of soil organic matter on microbial function

• Microbial diversity

  • Wide range of substrates supports many metabolic pathways, encouraging microbial diversity

• Store and release (recycle) energy

  • Primary repository of chemical energy used in microbial respiration, drives all major nutrient cycles

• Plant growth promotion

  • Supports higher levels of microbes which may benefit plant growth through disease suppression 

    • e.g. beans have symbiotic relationship with bacteria which fix nitrogen from air, so you don’t need to add fertiliser

Effect of soil organic matter on plant growth

• Seed germination and root growth

  • Improves seed imbibement and access to nutrients, reduces physical force on growing roots

• Buffer acidity, sodicity

  • High CEC of soil can buffer and reduce adverse chemistry

Effect of soil organic matter on waste management

• Sequester (hold or transform) biotoxic elements

  • High CEC can reduce metal mobility

• Degrade organic substances

  • Supports diverse microbial population that can degrade xenobiotics

Decomposition

Decomposition involves the breakdown of large organic molecules into smaller, simpler components

List the organic compounds in order of decomposition rate.

• Sugars, starches, and simple proteins 

• Crude proteins 

• Hemicellulose

• Cellulose  

• Fats and waxes 

• Lignins and phenolic compounds

What are the four general processes that take place when OM is added to the soil (under aerobic conditions)?

• Oxidation 

• Release 

• Synthesis 

• Protection

What reactions do microbes govern after the degradation of OM?

• Plant carbon compounds are enzymatically oxidised to produce carbon dioxide, water, energy, and decomposer biomass 

• Essential nutrient elements (N, P, S) are released and/or immobilised by a series of specific reactions 

• New compounds are synthesised by microbes as cellular constituents or as breakdown products or secondary metabolites 

• Some of the original plant compounds, their breakdown products and microbial compounds become physically, or chemical protected from further microbial decay

Why is C:N ratio important in organic residues?

• Intense competition among microorganisms for available soil nitrogen occurs when residues having a high C:N ration are added to soils 

• The residue C:N ratio helps determine the rate of decay and the rate at which nitrogen is made available to plant (N is the primary source of nutrition for plants) 

  • This is why increasing soil N increases yield

Factors to keep in mind to manage carbon in soils

• Carbon is removed from the soil when produce is harvested 

• Temperature, moisture and soil texture determine the concentration of OM in surface soils

• Constant tillage can be unaffordable and speed up OM decomposition through oxidation and sunlight exposure

List the important soil organisms (by size)

• Microorganisms

  • Viruses 

  • Bacteria 

  • Nematoda 

  • Protozoa (amoeba, flagellates) 

  • Rotifera

• Meso-organisms 

  • Acari (mites, ticks) 

  • Collembolia (springtails) 

  • Probura and diplura 

  • Isoptera (termites) 

• Macro-organisms

  • Oligochaeta (microdriles, earthworms)

  • Myriapoda (symphylans, centipedes, millipedes) 

  • Other arachnids (pseudoscorpions, spiders, harvesters)

  • Crustacea (isopods, amphipods) 

  • Coleoptera (beetles) 

How do organisms play a fundamental role in soil processes?

• Facilitate carbon cycling

• Facilitate nutrient cycling

• Facilitate decomposition

As a result of this metabolism, soil is created and stabilized and carbon dioxide, heat energy, and mineral nutrients are released into the soil environment.

What identifying features of specific groups of soil organisms determine their importance?

• The numbers of individuals in the soil 

• Their weight (biomass) per unit volume or area of soil

• Their metabolic activity 

What factors determine soil organism numbers?

• Soil organism numbers are influenced primarily by the amount and quality (especially the C and N content) of food available 

• Physical factors

  • e.g. moisture and temperature

• Biotic factors

  • e.g. predation and competition 

• Chemical characteristics of the soil

  • e.g. pH, dissolved nutrients, and salinity

• Environmental conditions affecting the growth and activity of soil microorganisms: 

  • e.g. organic resources, oxygen requirements (aerobic or anaerobic), soil moisture and temperature 

*most activity occurs at the soil surface (the most dynamic layer of soil)

What are the beneficial effects of soil organisms on plant communities?

• Soil organic matter formation and nutrient cycling 

  • Decompose dead plant tissues 

  • Assimilate wastes from animals and humans and other OM 

    • Degrade toxins

    • Microbes synthesise new compounds (some stabilise soil structure) 

  • Dead microbes are part of soil humus 

  • Bacteria, fungi and archaeans may be sources of N, P and S (extracted in soil solution) 

• Breakdown of toxic compounds 

  • Some of the toxics are produced by soil organisms, added on purpose (agrochemicals) or accidentally (environmental contamination) 

  • Biologically produced toxins are prone to microbial breakdown 

  • Fungi and soil prokaryotes are able to breakdown some toxins as well 

• Inorganic transformations 

  • Oxidative processes stimulated by soil microorganisms 

    • e.g. we usually apply nitrogen as urea which is degraded as ammonium to nitrates (which plants love) 

• Nitrogen fixation 

  • The fixation of elemental nitrogen gas into compounds usable by plant is an important microbial process 

  • Actinomycetes in the genus Frankia fix major amounts of nitrogen in forest ecosystems 

  • Cyanobacteria are important in flooded rice paddies, wetland, and deserts 

  • Rhizobia bacteria are the most important group for the capture of gaseous nitrogen in grassland and agricultural soils  

• Rhizobacteria 

  • Bacteria especially adapted to living in the rhizosphere (the zone around plant roots) are termed rhizobacteria, many of which are beneficial to higher plants (the so-called plant growth-promoting rhizobacteria) 

  • Certain rhizobacteria promote plant growth in other ways, such as enhanced nutrient uptake or hormonal stimulation   

• Mycorrhiza 

  • Symbiotic relationship between certain fungi and roots of higher plants; they play crucial roles in plant nutrition, soil biology and soil chemistry 

  • The most frequently reported benefit is enhanced ability of plants to take up P from low-phosphorus soils 

    • e.g. ectomycorrhizal are fungi, simulated by root exudates, that cover the surface of feeder roots with a fungal mantle. Endomycorrhiza are fungal hyphae that actually penetrate cortical root cell walls and once inside the plant cell form small, highly branched structures known as arbuscules   

• Plant pests and parasites 

  • Soil fauna include many herbivorous soil fauna that are injurious to the plants they feed on 

  • Microbes and place disease 

    • Disease infestations (great variety) 

  • The fungi that are responsible for the majority of soilborne plant diseases  

    • e.g. Agents of plant diseases  like Pythium, Fusarium, Phytophthora, and Rhizoctonia Fungi 

    • e.g. Symptoms include damping-off, root rots, leaf blights and wilts  

What are soil colloids and the soil colloidal fraction?

The fraction of the soil made up collectively of small (<0.002 mm) inorganic and organic particles (clay and humus). Colloids are highly reactive materials with electrically charged surfaces (majority negative). Due to their size and shape, they give the soil an enormous amount of reactive surface area.

General properties of soil colloids

• Size 

• Surface area 

  • The smaller the size of the particles in a given mass of soil, the greater the surface area 

  • Larger surface areas attracts more nutrients and contaminants 

• Surface charges 

  • For majority of soil negative charge predominates (exception in very acidic soils) 

• Adsorption of cations and anions 

  • Mostly attraction of positively charged ions (cations) to the surface of negatively charge soil colloids 

• Adsorption of water 

  • Greater surface area of the soil colloids, the greater the amount of water held when the soil is air-dry  

Why do sands leach quickly?

• Pore spaces and surface area play a dominant role in transport processes of soil

• Soil with a high hydraulic conductivity rate facilitate increased and rapid water movement through the soil which contributes to leaching 

Why do clay minerals hold more water and nutrients?

• Clay minerals have a layered structure and a large surface area that can absorb water and nutrients 

• More clay indicates more positions to hold cations

• Low clay content means fewer positions to hold cations

Humus

Consists of highly decomposed organic matter that retains water and nutrients. These colloids have a complex structure and are chemically composed mainly of C, H and O.

Why do we add organic matter to soils?

Organic amendments (e.g. compost) are added to soil because humus increases surface area, nutrients, water holding capacity, porosity and carbon stocks .

• Soil is negatively charged therefore, some of the cations (positively charged) will be easily absorbed onto the soil 

• Sometimes you need to be careful when you add fertiliser as nitrates can be easily leached

  • This is because there is no exchange between anions (negative charge) and soil particles (also negative charge).

What is cation exchange capacity (CEC) and why is it important?

A measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations) but allow these to exchange with other positively charged particles in the surrounding soil solution.

• CEC is used as a measure of soil fertility: it indicates the capacity of the soil to retain several nutrients 

• Bigger CEC rates mean greater nutrient retention

Soil aeration

Soil must be well ventilated for plant roots and other soil organisms to readily carry on respiration. This allows the exchange of gases between the soil and the atmosphere to supply enough oxygen (O2), while preventing the potentially toxic accumulation of gases such as carbon dioxide (CO2), methane (CH4) and ethylene (C2H6).

However, hydrophytes are able to grow in saturated soils that are virtually devoid of oxygen (e.g. the unique root system of mangroves). 

Factors affecting soil aeration

• Drainage of excess water 

• Rates of respiration in the soil (plant roots and microbial activity) 

• Soil profile characteristics (layering) 

• Soil heterogeneity (tillage, pore sizes, plant root pathways) 

• Seasonal differences (dry and wet phases)

• Effects of vegetation (increased transpiration – water table)

What factors regulate oxygen availability in the field?

• Soil macroporosity 

• Soil water content 

• O2 consumption by respiring organisms (including plant roots and microorganisms)

Soil temperature

The temperature of a soil greatly affects the physical, biological, and chemical processes occurring in that soil and in the plants growing on it. Temperature impacts seed germination and plant emergence, root shoot growth and function (water and nutrient uptake), and photosynthesis (optimum temp range).

What soil processes does temperature influence?

• Pedogenetic processes

  • Weathering of minerals and soil formation, accumulation of soil organic matter 

• Soil water storage (evaporation), movement of water, freezing and thawing 

• Soil respiration (gas exchange) 

• Nutrient cycling 

• Microbial processes

How do we control soil temperature?

• Organic mulches and plant-residue management 

  • Applying different coloured mulch (seal the surface) can reduce evaporation loss, leaching and act as weed control

• Plastic mulches

  • Can be environmentally problematic 

• Soil moisture to cool crops 

  • Drainage and irrigation systems

    • e.g In Europe farmers apply an irrigation system in winter to insulate (freeze) crops like cherries to prolong the period before flowering 

• Tillage practices (raised beds)

Soil heat capacity

The ability of a substance to hold or store heat. The greater its heat capacity, the more heat it can gain (or lose) per unit rise (fall) in temperature.

Thermal conductivity

The ability of soil to conduct heat. It describes the heat flow in response to temperature gradient (change).