One of the few benefits of this prolonged lockdown has been the proliferation of webinars or online seminars that can be accessed from around the world. Perhaps they were always there, but our limited ability to travel has encouraged us to listen to people we may previously have not known.
Given my interest in soil, I was tempted a few weeks ago to listen in on one of the Cré sessions titled “SOIL – The Essence of Life on our Planet”. The address was given by Dr Rattan Lal from Ohio State University, a man with many titles and distinctions. My interest was based on his knowledge of soils and soil science.
While most of his comments related to cropped soils, that is a matter of relatively recent use, as most soils can be used for a range of enterprises. Sometimes, it is climate, rather than soil type, that has the greater influence on how land is used, but there are certainly different soils types too.
The three legs
He began by talking about the importance of carbon or organic matter in soil. He spoke about something I have often written about – the three pillars of soil health, the three-legged stool. The three legs are:
Physical – structure and texture.Chemical – soil fertility, which is also important for productivity, but can be very curtailed by poor soil structure.Biological – the presence of the trillions of organisms that give soil life.Dr Lal added a fourth leg. We might say that this adds increased stability to the stool, but it is still dependent on the other three. I prefer to describe it as the seat of the stool, rather than a fourth leg. This additional component is the ecological services a soil should provide.
The ecological seat
So, what are the ecological services a soil provides? Well, some are easy. Soil is where you build structures. Soil is where water should go when it rains. Soil should act as a filtering agent for nutrients and other compounds that pass through it in water or air. Soil provides anchorage and food for plants and the creatures that live in it. Soil provides a home for the recycling of nutrients and the many organisms involved in the process. As well as many other functions, the ecology of the soil delivers traits and nutrients that add to its productivity, regardless of what it is growing.
Soil should carry a range of aggregate sizes and show lots of root growth.
Putting all four together – the three legs and the seat – gives a healthy soil with good function. We all know what this looks like, even if it is only from memory. That dark colour in the topsoil, which is full of roots that can grow easily through the well-structured soil, is given to it by the high organic matter level. The roots effectively resurrect the nutrients from decaying organic matter to turn them back into plant material. The trillions of microorganisms compete for those same nutrients, as they attempt to grow their numbers in the presence of recycling organic matter.
That nutrient recycling process is generally capable of growing 5-6t DM/ha without additional nutrition when a soil is functioning well
This is the process that enables old unfertilised grassland to perform. That nutrient recycling process is generally capable of growing 5-6t DM/ha without additional nutrition when a soil is functioning well. Such soils are generally capable of good water percolation and in doing that, pull out nutrients and other compounds from the water, leaving it cleaner as it passes on to drains and rivers.
As a general rule, water that goes through the soil will be cleaner than water that flows over the surface.
The state of the soil
Contrast that picture of natural, old grassland that feeds itself from recycling with one that is undergoing intensive modern management, with much higher fertiliser input and high stocking density.
Contrast it also to continuous tillage soils, where the soil is forcibly torn apart every year, structure has deteriorated, compaction is common and there is no source of organic matter return. When we kill the natural part, we have to put more in to get less out.
... when water can no longer percolate, it runs over the surface, taking with it the fine soil as brown water
Contrast it once again to land that has been left idle with no vegetation. Rain beating on the surface results in continuous structure degradation and the fine particles produced from the grinding of the soil particles wash down with percolating water to fill the natural pore spaces in the soil. And when water can no longer percolate, it runs over the surface, taking with it the fine soil as brown water.
A slumped soil shows very poor structure and slows water percolation.
The absence of growing plants means no roots to keep the soil loosened and no leaves to assimilate carbon. Such soils slump, which means they fill up with fine soil, are slower to dry and more difficult and expensive to plough and cultivate.
To keep that seat on the stool, it is essential to have its three legs functioning properly. A soil that is not healthy and biologically active cannot be an ecosystems provider.
This is what the EU, and farmers, want soils to be. Such a soil will be a more productive, it will recover better from damage, it will carry higher yield potential in any use, it will let more water through and filter it better and it will produce higher yields. But none of this can continue to happen if the soil is not properly fed.
Wise old words
I want to give Dr Lal the last few comments here. In that seminar, he said a few simple things that we would all do well to remember.
“If you take more out than you put in, the soil will degrade. Soil can be a source or a sink for carbon.” That means that soil can either lose more carbon than it takes in or it can hold more than it gives off – management is the difference. This applies to all land uses.
The forced decoupling of these nutrients destroys this ability, leaving you with problems such as emissions, soil erosion, algal blooms etc
Talking about the natural degradation of organic matter in the soil by microorganisms, he commented: “The natural coupling of nutrients in the soil generates the ecosystem services. The forced decoupling of these nutrients destroys this ability, leaving you with problems such as emissions, soil erosion, algal blooms etc.”
These last few words are relevant to us all, in all walks of life, and the soil is no different. ‘Dose is the difference between medicine and poison.’ A correct amount is good, but too much can be deadly. This applies equally to fertiliser and organic manures.
To conclude, he stated that: “Soil health is helped by profitability, because farmers can afford to do what is right. People must be willing to pay for these ecosystem services, if not they have no right to demand them.”
Soils cannot be healthy unless the three elements – physical, chemical, and biological – are functioning properly.Together, these three elements enable a soil to fulfil ecological services, such as water percolation and filtration.Soils need to be fed, but dose is the difference between medicine and poison and we need to protect its natural systems.
One of the few benefits of this prolonged lockdown has been the proliferation of webinars or online seminars that can be accessed from around the world. Perhaps they were always there, but our limited ability to travel has encouraged us to listen to people we may previously have not known.
Given my interest in soil, I was tempted a few weeks ago to listen in on one of the Cré sessions titled “SOIL – The Essence of Life on our Planet”. The address was given by Dr Rattan Lal from Ohio State University, a man with many titles and distinctions. My interest was based on his knowledge of soils and soil science.
While most of his comments related to cropped soils, that is a matter of relatively recent use, as most soils can be used for a range of enterprises. Sometimes, it is climate, rather than soil type, that has the greater influence on how land is used, but there are certainly different soils types too.
The three legs
He began by talking about the importance of carbon or organic matter in soil. He spoke about something I have often written about – the three pillars of soil health, the three-legged stool. The three legs are:
Physical – structure and texture.Chemical – soil fertility, which is also important for productivity, but can be very curtailed by poor soil structure.Biological – the presence of the trillions of organisms that give soil life.Dr Lal added a fourth leg. We might say that this adds increased stability to the stool, but it is still dependent on the other three. I prefer to describe it as the seat of the stool, rather than a fourth leg. This additional component is the ecological services a soil should provide.
The ecological seat
So, what are the ecological services a soil provides? Well, some are easy. Soil is where you build structures. Soil is where water should go when it rains. Soil should act as a filtering agent for nutrients and other compounds that pass through it in water or air. Soil provides anchorage and food for plants and the creatures that live in it. Soil provides a home for the recycling of nutrients and the many organisms involved in the process. As well as many other functions, the ecology of the soil delivers traits and nutrients that add to its productivity, regardless of what it is growing.
Soil should carry a range of aggregate sizes and show lots of root growth.
Putting all four together – the three legs and the seat – gives a healthy soil with good function. We all know what this looks like, even if it is only from memory. That dark colour in the topsoil, which is full of roots that can grow easily through the well-structured soil, is given to it by the high organic matter level. The roots effectively resurrect the nutrients from decaying organic matter to turn them back into plant material. The trillions of microorganisms compete for those same nutrients, as they attempt to grow their numbers in the presence of recycling organic matter.
That nutrient recycling process is generally capable of growing 5-6t DM/ha without additional nutrition when a soil is functioning well
This is the process that enables old unfertilised grassland to perform. That nutrient recycling process is generally capable of growing 5-6t DM/ha without additional nutrition when a soil is functioning well. Such soils are generally capable of good water percolation and in doing that, pull out nutrients and other compounds from the water, leaving it cleaner as it passes on to drains and rivers.
As a general rule, water that goes through the soil will be cleaner than water that flows over the surface.
The state of the soil
Contrast that picture of natural, old grassland that feeds itself from recycling with one that is undergoing intensive modern management, with much higher fertiliser input and high stocking density.
Contrast it also to continuous tillage soils, where the soil is forcibly torn apart every year, structure has deteriorated, compaction is common and there is no source of organic matter return. When we kill the natural part, we have to put more in to get less out.
... when water can no longer percolate, it runs over the surface, taking with it the fine soil as brown water
Contrast it once again to land that has been left idle with no vegetation. Rain beating on the surface results in continuous structure degradation and the fine particles produced from the grinding of the soil particles wash down with percolating water to fill the natural pore spaces in the soil. And when water can no longer percolate, it runs over the surface, taking with it the fine soil as brown water.
A slumped soil shows very poor structure and slows water percolation.
The absence of growing plants means no roots to keep the soil loosened and no leaves to assimilate carbon. Such soils slump, which means they fill up with fine soil, are slower to dry and more difficult and expensive to plough and cultivate.
To keep that seat on the stool, it is essential to have its three legs functioning properly. A soil that is not healthy and biologically active cannot be an ecosystems provider.
This is what the EU, and farmers, want soils to be. Such a soil will be a more productive, it will recover better from damage, it will carry higher yield potential in any use, it will let more water through and filter it better and it will produce higher yields. But none of this can continue to happen if the soil is not properly fed.
Wise old words
I want to give Dr Lal the last few comments here. In that seminar, he said a few simple things that we would all do well to remember.
“If you take more out than you put in, the soil will degrade. Soil can be a source or a sink for carbon.” That means that soil can either lose more carbon than it takes in or it can hold more than it gives off – management is the difference. This applies to all land uses.
The forced decoupling of these nutrients destroys this ability, leaving you with problems such as emissions, soil erosion, algal blooms etc
Talking about the natural degradation of organic matter in the soil by microorganisms, he commented: “The natural coupling of nutrients in the soil generates the ecosystem services. The forced decoupling of these nutrients destroys this ability, leaving you with problems such as emissions, soil erosion, algal blooms etc.”
These last few words are relevant to us all, in all walks of life, and the soil is no different. ‘Dose is the difference between medicine and poison.’ A correct amount is good, but too much can be deadly. This applies equally to fertiliser and organic manures.
To conclude, he stated that: “Soil health is helped by profitability, because farmers can afford to do what is right. People must be willing to pay for these ecosystem services, if not they have no right to demand them.”
Soils cannot be healthy unless the three elements – physical, chemical, and biological – are functioning properly.Together, these three elements enable a soil to fulfil ecological services, such as water percolation and filtration.Soils need to be fed, but dose is the difference between medicine and poison and we need to protect its natural systems. 
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