Studied by 0 people
Looks like no one added any tags here yet for you.
What is Integrated Farm Management (IFM)?
Making the best use of available resources so they complement each other to produce profitable crops while practising environmental stewardship and using energy and manufactured inputs responsibly.
What seven things does the soil consist of?
- Organic matter (humus)
- Sand, silt and clay (minerals)
- Aggregates (stones, rocks etc)
- Living organisms (macro and micro)
- Water
- Air
- Nutrients and chemicals (macro and micro)
What is soil texture?
The relative proportions of sand, silt, and clay particles within the soil.
Which additional component is included in soil texture when abundant (above 8%)?
Organic matter
What is the composition of clay soils?
Heavy and dense, requiring more energy to move/work
What is the size range of clay particles?
Less than 0.002mm in diameter.
How do clay particles arrange themselves?
Clay particles are plate-like and have a large surface area. These stick together and stack on top of each other, resulting in cloddy soil when worked.
Why are clay soils resilient to weathering?
The plate-like clay particles bond strongly due to flocculation, resisting breakdown.
What is soil flocculation and what does this contribute towards?
The binding together of clay particles by cations such as Ca and Mg, enhancing the strength and structure of clay soils
Which cation is most effective at soil flocculation and why?
Calcium is most effected due to its larger ionic radius and weaker hydration shell
How does water surface tension hold clay particles together?
Water between clay particles creates surface tension, causing the particles to adhere and maintain a cohesive structure.
Why do clay soils have a high water retention and what benefits does this bring?
Due to small capillary spaces, making them less prone to drought and often higher yielding.
What is the electrical charge of clay particles?
Negative
How do clay particles reduce nutrient leaching?
Positively charged nutrient molecules stick to negatively charged clay surfaces, keeping nutrients in the soil solution and reducing leaching.
What is cation exchange capacity (CEC) and why is it high in clay soils?
Cation exchange capacity measures how many positively charged ions (cations) a soil can hold; clay's negative charge gives it a high CEC.
What happens when a cation attaches to a clay particle?
Another is released back into solution to maintain equilibrium
Which cations commonly attach to clay particles?
Potassium (K), Calcium (Ca), Magnesium (Mg), Copper (Cu), Manganese (Mn), Iron (Fe), and Zinc (Zn) are common cations in clay soils.
Why do calcium (Ca) and magnesium (Mg) aid flocculation in clay soils?
Calcium and magnesium have two positive charges that can be sandwiched between clay particles, helping bind them together into stable structures.
Which are the most abundant anions in clay soils?
Calcium and Magnesium
Why are negatively charged nutrient and organic matter molecules more prone to leaching in clay soils?
They are repelled by clay's negative surface charge, making them more likely to be washed away.
Which are some examples of anions that can leach in clay soils?
Examples include sulfate (SO₄²⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), borate (BO₃³⁻), and molybdate (MoO₄²⁻).
Why are clay soils said to be self structuring?
They expand when wet and then shrink when dry, forming vertical cracks which allow water to penetrate deeper and reach the roots
Why do clay soils smear when worked if wet?
Clay particles are sticky when wet, causing the soil to smear rather than crumble when cultivated which forms pans in the soil
What happens to clay soils in very dry conditions?
They will crack leading to preferential leaching
What is the drainage like in clay soils?
They are slow draining and more prone to waterlogging
How do clay soils respond to temperature changes?
Clay soils take longer to warm up and longer to cool down due to their higher water content.
Why do water particles in clay soils take longer to heat or cool than air particles?
Water requires more energy to change temperature than air (4x as much), so soils with higher water content change temperature more slowly.
What is the shape of sand particles?
Irregular, often cube-like, creating more air space in the soil.
What is the size range of sand particles?
Between 0.063mm and 2mm in diameter.
How can sand cause wear to machinery and plant tissue?
Sand is abrasive, and wind-driven particles can erode machinery parts and damage plant tissues.
Does sand have any electrical charge?
No
Why are sandy soils considered light and low in density?
Sandy soils have larger pore spaces and fewer fine particles, making them easier to work and lighter in weight (don't stick together)
How does sand affect water drainage?
Sandy soils are free-draining because the large pore spaces allow water to pass through quickly, making them less prone ro waterlogging
How quickly do sandy soils react to temperature changes and why?
Sandy soils warm up and cool down rapidly because they contain less water, which allows faster temperature changes.
How susceptible are sandy soils to waterlogging?
Less prone to waterlogging due to their high drainage capability.
Why are sandy soils prone to nutrient leaching (except phosphate)?
Rapid drainage due to their poor structure washes away most soluble nutrients, though phosphate tends to adhere to soil particles more strongly.
Why are sandy soils prone to erosion?
The large, loose particles in sandy soils can be easily carried away by wind or water.
Why do sandy soils have weak structure and become compacted easily?
Without much cohesion between particles, sandy soils collapse under pressure, leading to compaction, slumping and capping
What is slumping in sandy soils?
Slumping occurs when a seedbed disintegrates back into an unconsolidated state after rain, losing its structure.
What is capping in sandy soils and why does it hinder seedlings?
Capping happens when the soil surface dries into a crust after slumping, preventing seedlings from emerging through the hardened layer.
What is the size range of silt particles?
Between 0.002mm and 0.063mm in diameter.
Why is silt considered a middle ground between clay and sand?
Silt's particle size and properties fall between those of clay and sand, providing balanced drainage and moisture retention (valuable land as they are best of both worlds)
Does silt have any electrical charge?
No
How is silt formed?
By sedimentation, where fine particles settle out of water and wind-blown deposits.
How easy is it to work with silt soils?
Silt soils are easy to cultivate, offering workable tilth under many conditions.
Why are silt soils prone to compaction, slumping, and capping?
Their fine but non-cohesive particles can stick together when wet and harden into a crust when dry.
How does silt compare to sand and clay in terms of water and nutrient retention?
Silt retains water and nutrients better than sand but not as well as clay
What is the approximate organic matter percentage in soils of East England and Scotland?
Around 2%
When is a soil classified as an organic soil?
When OM content exceeds 8%
What is the OM% of organic mineral soils?
8% to 20% (organic sandy loam)
What is the OM% of peaty soils?
20% to 35%
What is the OM% of peat soils?
> 35%
How does organic matter affect cation exchange capacity?
Organic matter adds cation exchange sites, increasing the soil's ability to hold cationic nutrients (K, Ca, Mg etc)
How can soil pH impact trace element deficiencies in organic soils?
Higher organic matter and certain pH levels can reduce the availability of trace elements, leading to possible deficiencies.
How does organic matter mineralise to release nutrients such as nitrogen and what does this depend on?
Microbial decomposition of organic matter releases nutrients over time, a process dependent on soil conditions like temperature and moisture.
What structural issue do peaty and peat soils face?
Peaty and peat soils often lack a firm structure and are prone to erosion due to their high organic content.
What is soil structure?
The aggregation and forming together of soil particles
What five things should seed bed structure allow?
- Good seed to soil contact
- Poor spares for good root development, aeration and drainage
- Drilling at uniform depth
- Coverage of the seed
- Smooth drilling operation
How is soil typically divided for agricultural purposes?
Topsoil (25-30 cm) and subsoil, each having different requirements and characteristics.
What is the depth of the topsoil and why is it important?
The topsoil is generally 25-30 cm deep and is crucial for seedbed preparation and root establishment.
Why is the subsoil important?
The subsoil is key for drainage and deeper root development, influencing overall plant health.
Why should topsoil contain gaps for air?
Air spaces in topsoil allow roots and soil organisms to breathe and support healthy plant growth.
Why should seedbed aggregates be small?
To create good seed-to-soil contact (tilth), enabling easier access to moisture and nutrients for seedlings.
What does the optimum size of top soil aggregation depend on?
The size of the seed
Why must a seedbed be both loose and firm?
A loose seedbed promotes root development and aeration, while firmness ensures good seed/root to soil contact for anchorage and nutrient uptake.
What will aggregation be like within the top soil below the seedbed?
The aggregates will be larger but still small and loose enough to allow for good root development, drainage and airflow
Why is subsoil important for drainage and root development?
Subsoil with good structure and vertical cracks allows water to drain and roots to explore deeper layers (some crop roots can penetrate to well over 1m)
Why are vertical cracks desirable in subsoil?
Vertical cracks improve aeration, water penetration, and root growth beyond the topsoil layer.
Why are horizontal pans undesirable in subsoil?
Horizontal pans form hard layers that restrict root growth and water movement, creating straight, impenetrable lines in the soil.
Do carboniferous clay soils naturally release potash?
No
