Soil
What is soil?
What is soil?
Dirt? Where plants grow? The ground beneath our feet?
Dirt? Where plants grow? The ground beneath our feet?
Dirt? Where plants grow? The ground beneath our feet?
Soil is all those things and much more. It’s the perfect example of a word that’s been around for longer than the understanding of the material it describes.
The more closely soil is examined, the more complex it becomes. It is not just a medium in which multiple processes take place, it is a living ecosystem with infinite variety across time and space. Soil is made up of a mineral component – usually weathered rocks - and an organic component, comprised of living organisms, the material they produce and dead organisms in various states of decomposition.
The organic part is usually in the upper of a series of layers – known as horizons – and is mostly what we see.
The texture of soil, determined by the relative abundance of particles of sand, silt and clay, is well understood, and is crucial to our understanding of how soils behave under different environmental conditions. Soils rich in sand, the largest of the components, will hold less water for example than a soil made up of clay, the smallest.
The mixture of the organic and mineral components adds complexity to the soil system along with living organisms such as bacteria, fungi, insects and worms and lead to the profile of a soil.
Plants have a symbiotic relationship with the soil, drawing on its nutrients, water and warmth and recycling nutrients and organic matter in return. About a third of the carbon taken up by plants from the atmosphere through photosynthesis is stored in the soil due to the microbiome around their roots.
The majority of plant species have symbiotic relationships with fungi, and direct carbon to them via their roots. Between 10-50% of carbon gained by plants can enter the soil in this way. Although a lot of the carbon absorbed by fungi is respired, a portion remains over longer periods.
Overuse of pesticides and fertilizers can interfere with these processes, reducing the amount of carbon stored. Different management approaches can also speed them up or slow them down. For example, deep tilling, which exposes the soil to oxygen, can lead to increased loss of carbon.
Understanding soil systems, their variety and complexity, is vital for developing sustainable farming practices which are sensitive to the changes brought about by different conditions and seasons, as each square metre of each field will have different needs and outcomes.
Dirt? Where plants grow? The ground beneath our feet?
Soil is all those things and much more. It’s the perfect example of a word that’s been around for longer than the understanding of the material it describes.
The more closely soil is examined, the more complex it becomes. It is not just a medium in which multiple processes take place, it is a living ecosystem with infinite variety across time and space. Soil is made up of a mineral component – usually weathered rocks - and an organic component, comprised of living organisms, the material they produce and dead organisms in various states of decomposition.
The organic part is usually in the upper of a series of layers – known as horizons – and is mostly what we see.
The texture of soil, determined by the relative abundance of particles of sand, silt and clay, is well understood, and is crucial to our understanding of how soils behave under different environmental conditions. Soils rich in sand, the largest of the components, will hold less water for example than a soil made up of clay, the smallest.
The mixture of the organic and mineral components adds complexity to the soil system along with living organisms such as bacteria, fungi, insects and worms and lead to the profile of a soil.
Plants have a symbiotic relationship with the soil, drawing on its nutrients, water and warmth and recycling nutrients and organic matter in return. About a third of the carbon taken up by plants from the atmosphere through photosynthesis is stored in the soil due to the microbiome around their roots.
The majority of plant species have symbiotic relationships with fungi, and direct carbon to them via their roots. Between 10-50% of carbon gained by plants can enter the soil in this way. Although a lot of the carbon absorbed by fungi is respired, a portion remains over longer periods.
Overuse of pesticides and fertilizers can interfere with these processes, reducing the amount of carbon stored. Different management approaches can also speed them up or slow them down. For example, deep tilling, which exposes the soil to oxygen, can lead to increased loss of carbon.
Understanding soil systems, their variety and complexity, is vital for developing sustainable farming practices which are sensitive to the changes brought about by different conditions and seasons, as each square metre of each field will have different needs and outcomes.