A few weeks ago Teagasc held a workshop on soil quality and health for advisors, consultants and farmers. This proved to be an excellent event with a number of simple and visual messages.
There were many different topics addressed, including soil structure assessment, managing soil compaction, cultivation systems for different soils and organic matter and catch crops for soil health.
All had their own messages, but perhaps the most striking one was very visual – the impact of having a growing crop on a stubble post harvest, versus not.
Soils carry out many functions and their ability to do any or all of these depends to some degree on how they are managed.
Good soil structure and health is key to future proofing Irish agriculture
During the growing season, soils supply plant nutrients, enable crop rooting and anchorage, store and resupply water over the summer months, perform many biological functions to include suppressing pathogens, filter nutrients from percolating water, release nutrients through mineralisation and they break down pesticides and organic and inorganic substances in the ground, to name but a few.
Good soil structure and health is key to future proofing Irish agriculture.
Importance of a growing crop
Part of the workshop involved topics related to stubble and tillage ground. While the field in question was a winter barley stubble following grass, the impact of having plants of any sort growing on the stubble was dramatic.
A number of different catch crops were grown in one area, which included tillage radish, clover, natural regeneration, mixtures etc and one plot area had been kept free of vegetation since harvest. The impact was dramatic.
Almost regardless of the crops grown, when a cube of the root zone was dug up and left on a table, the soil broke apart almost instantly leaving a pile of nice crumbly, well-structured soil from which the roots were easily be pulled away.
Patrick Forristal and John Pettit showed that the more vigorous the root structure of the crop, the more the soil cube broke up.
Earthworms were often found in direct association with the plant roots, perhaps consuming some of the sugars being exuded from them.
The slumped soil, where no crop was growing, broke up into big lumps.
Compare that to where nothing was allowed to grow. This area had not been deliberately compacted, but a cube of that plot came up as a single block, which took some force to break. This was still a fresh ley soil structure. This soil had slumped, tightened up and lost much of its porosity (see pictures above).
It is important to remember that soil is naturally degraded by different aspects of weather, with rain being a very significant factor in our climate.
When soil structure is broken apart by rain, the finer clay and silt fractions tend to wash away and move in the flow of water. If this runs across the surface in a very worn field, the brown water can often result in gully erosion and run into drains or out the field gate.
The brown ‘soil’ is carrying with it fine clay particles and the nutrients which are attached. This is a straight loss of soil and fertility from the field.
Where the water can percolate down into the soil, the fine particles tend to flow to the point of first constriction and then build up in the soil pores.
The ground on which nothing was growing was now much tighter
This effectively clogs up the soil, making it stiff and more difficult to break down. This problem is further exacerbated by the absence of growing leaves to protect the soil from the rain and roots to help keep the soil open. These combined actions prevent the soil from tightening on itself and therefore make it easier to cultivate subsequently.
The ground on which nothing was growing was now much tighter and would most likely take longer to dry out as well as taking more power to cultivate, regardless of the establishment system used.
While ground beneath a growing crop may take slightly longer to dry out due to canopy cover, the looser nature of the soil should help it warm up faster and dry out quickly in good drying conditions.
Let the roots cultivate for you
One of the lesser talked about potential benefits of catch crops relates to the condition of the soil thanks to the roots.
Dermot Forrestal explained the need to match machine type and system with soil type and situation.
When a worn soil is improved following a number of years of catch cropping or organic matter incorporation, one of the big potential savings is the ability to drill directly into the crop residue without ploughing or deep cultivation.
That represents a significant cost saving in time and the improving soil should simultaneously result in higher yield potential with lower nitrogen requirement. Dermot Forristal spoke about the options in a plot of catch crop where a Weaving direct drill had gone through.
Direct drills can sow directly into a standing cover crop.
A lot of the work being done at Johnstown is looking at soil health in terms of the physical structure and the biological families that live in soil.
Fiona Brennan is doing good work in this area and she stressed that a healthy soil depends on it being fed with organic matter.
A range of products were being tested under catch crops and some, like straw itself, looked exceptionally impressive.
While all of the materials tested had the potential to provide nutrients for the crop, the visual results shown by Martin Bourke of Teagasc may have been influenced by the relative freshness of this ground.
A soil pit
One field at Johnstown had been in tillage (maize production) for a number of years in the recent past.
This suffered serious structural damage in the harvest of 2012 and part of the field was put back to grass afterwards, while the remainder went to spring barley production. A soil pit was dug for the event, which spanned both recent field uses.
Giulia Bondi of Teagasc manned the soil pit, which still clearly showed the relatively deep compacted plough pan that formed in the years of maize production.
Giulia Bondi explains the consequences of previous soil management on the appearance and performance of the land around this soil pit. An old plough pan can be seen where it is exposed.
This particular field suffers from a rising water table, but the presence of the compacted layer means that water will lie on the surface following heavy rain.
What was very obvious from that soil pit was the better structure and the absence of the plough pan in the area that went on to grow spring barley up to this year.
This had been managed in a way to specifically help the problem, with deeper ploughing in dry years to help break up that pan and shallower ploughing in wet years when damage might occur.
Not only was there no pan and a nicer looking structure in this section, it also looked as if the subsoil was in somewhat better condition.
Soil structure
One of the very important functioning aspects of a soil is its structure. Good structure means that a soil is open and has good porosity with lots of air spaces, which enable roots to grow and breathe and water to percolate down through the soil.
Structure can be damaged when land is worked or travelled on in wet conditions and the danger of damage increases with higher soil moisture levels.
Structure is not necessarily a permanent feature of a soil, in that it can be made worse or better by farm practice.
Machine weight is one of the ever increasing pressures being imposed, but so is the pressure of workload and the need to get through work in sometimes less than ideal conditions.
Farmers need to be aware of the importance of structure to soil function and especially to crop growth.
There is a need to know the relative state of the structure of a field, or an area in a field, with the aim to improve it over time.
Poor structure takes more pressure and will tend to naturally break into big lumps with straight edges
Mark Plunkett and Cathal Somers of Teagasc explained the simple basics of good structure and pointed out the ease with which soil breaks apart as a good indicator. Good structure will break apart easily with little force.
Poor structure takes more pressure and will tend to naturally break into big lumps with straight edges, which require more energy to cultivate and, subsequently, consolidate.
The Teagasc men showed examples of both good and poor structure.
Assessing structure in tillage fields is different to grassland, in that it should be done at greater depth and the process is referred to as the double-spade method. Good structure should want to break up like brown bread, while poor structure will just break into smaller lumps.
A further test is to squeeze a lump between the thumb and index finger and see if just a little pressure will cause further breakage.
Questions over sub-soiling
Subsoiling is seen by some as a cure for damaged structure. This is largely because pulling metal through the ground helps remove surface water. But pushing surface water down into the profile may only be moving that water down to a greater depth for bigger problems.
A sub-soiler can be useful if one has a problem at uniform depth and the soil is very dry
David Wall and Brendan Burke of Teagasc had pulled a large five leg sub-soiler through the tillage part of the same field in which the soil pit was located. It had rained the previous night and the surface water had certainly gone down, but it was now down in the channels created by the legs. So solving one problem can often create another.
That said, a sub-soiler can be useful if one has a problem at uniform depth and the soil is very dry.
If the area that needs shattering is damp, it will not shatter and is likely to behave like putty and result in a new smeared layer deeper in the profile.
The summer of 2018 did a huge amount of this work for free
What is needed is for the soil to be shattered both vertically and horizontally to enable water movement and root growth. The closer this can be done to when the roots are actively growing, the better the chance of keeping these cracks open as the roots grow down through them.
The summer of 2018 did a huge amount of this work for free and part of the performance of harvest 2019 may relate to it.
Asked if subsoiling tramlines is a useful operation, the opinion was a cautious “no”.
Where these same tracks are likely to be used year after year, loosening the soil to depth in these areas could well result in a tendency to hold water at a greater depth following loosening. This is not what one wants for tramlines.
The discussion about subsoiling was mainly negative, because of the additional risks involved and the very uncertain yield benefit in most instances. We must always remember that subsoiling does not cure a structure problem, it merely opens up a soil to allow water and air to penetrate to a greater depth.
A few weeks ago Teagasc held a workshop on soil quality and health for advisors, consultants and farmers. This proved to be an excellent event with a number of simple and visual messages.
There were many different topics addressed, including soil structure assessment, managing soil compaction, cultivation systems for different soils and organic matter and catch crops for soil health.
All had their own messages, but perhaps the most striking one was very visual – the impact of having a growing crop on a stubble post harvest, versus not.
Soils carry out many functions and their ability to do any or all of these depends to some degree on how they are managed.
Good soil structure and health is key to future proofing Irish agriculture
During the growing season, soils supply plant nutrients, enable crop rooting and anchorage, store and resupply water over the summer months, perform many biological functions to include suppressing pathogens, filter nutrients from percolating water, release nutrients through mineralisation and they break down pesticides and organic and inorganic substances in the ground, to name but a few.
Good soil structure and health is key to future proofing Irish agriculture.
Importance of a growing crop
Part of the workshop involved topics related to stubble and tillage ground. While the field in question was a winter barley stubble following grass, the impact of having plants of any sort growing on the stubble was dramatic.
A number of different catch crops were grown in one area, which included tillage radish, clover, natural regeneration, mixtures etc and one plot area had been kept free of vegetation since harvest. The impact was dramatic.
Almost regardless of the crops grown, when a cube of the root zone was dug up and left on a table, the soil broke apart almost instantly leaving a pile of nice crumbly, well-structured soil from which the roots were easily be pulled away.
Patrick Forristal and John Pettit showed that the more vigorous the root structure of the crop, the more the soil cube broke up.
Earthworms were often found in direct association with the plant roots, perhaps consuming some of the sugars being exuded from them.
The slumped soil, where no crop was growing, broke up into big lumps.
Compare that to where nothing was allowed to grow. This area had not been deliberately compacted, but a cube of that plot came up as a single block, which took some force to break. This was still a fresh ley soil structure. This soil had slumped, tightened up and lost much of its porosity (see pictures above).
It is important to remember that soil is naturally degraded by different aspects of weather, with rain being a very significant factor in our climate.
When soil structure is broken apart by rain, the finer clay and silt fractions tend to wash away and move in the flow of water. If this runs across the surface in a very worn field, the brown water can often result in gully erosion and run into drains or out the field gate.
The brown ‘soil’ is carrying with it fine clay particles and the nutrients which are attached. This is a straight loss of soil and fertility from the field.
Where the water can percolate down into the soil, the fine particles tend to flow to the point of first constriction and then build up in the soil pores.
The ground on which nothing was growing was now much tighter
This effectively clogs up the soil, making it stiff and more difficult to break down. This problem is further exacerbated by the absence of growing leaves to protect the soil from the rain and roots to help keep the soil open. These combined actions prevent the soil from tightening on itself and therefore make it easier to cultivate subsequently.
The ground on which nothing was growing was now much tighter and would most likely take longer to dry out as well as taking more power to cultivate, regardless of the establishment system used.
While ground beneath a growing crop may take slightly longer to dry out due to canopy cover, the looser nature of the soil should help it warm up faster and dry out quickly in good drying conditions.
Let the roots cultivate for you
One of the lesser talked about potential benefits of catch crops relates to the condition of the soil thanks to the roots.
Dermot Forrestal explained the need to match machine type and system with soil type and situation.
When a worn soil is improved following a number of years of catch cropping or organic matter incorporation, one of the big potential savings is the ability to drill directly into the crop residue without ploughing or deep cultivation.
That represents a significant cost saving in time and the improving soil should simultaneously result in higher yield potential with lower nitrogen requirement. Dermot Forristal spoke about the options in a plot of catch crop where a Weaving direct drill had gone through.
Direct drills can sow directly into a standing cover crop.
A lot of the work being done at Johnstown is looking at soil health in terms of the physical structure and the biological families that live in soil.
Fiona Brennan is doing good work in this area and she stressed that a healthy soil depends on it being fed with organic matter.
A range of products were being tested under catch crops and some, like straw itself, looked exceptionally impressive.
While all of the materials tested had the potential to provide nutrients for the crop, the visual results shown by Martin Bourke of Teagasc may have been influenced by the relative freshness of this ground.
A soil pit
One field at Johnstown had been in tillage (maize production) for a number of years in the recent past.
This suffered serious structural damage in the harvest of 2012 and part of the field was put back to grass afterwards, while the remainder went to spring barley production. A soil pit was dug for the event, which spanned both recent field uses.
Giulia Bondi of Teagasc manned the soil pit, which still clearly showed the relatively deep compacted plough pan that formed in the years of maize production.
Giulia Bondi explains the consequences of previous soil management on the appearance and performance of the land around this soil pit. An old plough pan can be seen where it is exposed.
This particular field suffers from a rising water table, but the presence of the compacted layer means that water will lie on the surface following heavy rain.
What was very obvious from that soil pit was the better structure and the absence of the plough pan in the area that went on to grow spring barley up to this year.
This had been managed in a way to specifically help the problem, with deeper ploughing in dry years to help break up that pan and shallower ploughing in wet years when damage might occur.
Not only was there no pan and a nicer looking structure in this section, it also looked as if the subsoil was in somewhat better condition.
Soil structure
One of the very important functioning aspects of a soil is its structure. Good structure means that a soil is open and has good porosity with lots of air spaces, which enable roots to grow and breathe and water to percolate down through the soil.
Structure can be damaged when land is worked or travelled on in wet conditions and the danger of damage increases with higher soil moisture levels.
Structure is not necessarily a permanent feature of a soil, in that it can be made worse or better by farm practice.
Machine weight is one of the ever increasing pressures being imposed, but so is the pressure of workload and the need to get through work in sometimes less than ideal conditions.
Farmers need to be aware of the importance of structure to soil function and especially to crop growth.
There is a need to know the relative state of the structure of a field, or an area in a field, with the aim to improve it over time.
Poor structure takes more pressure and will tend to naturally break into big lumps with straight edges
Mark Plunkett and Cathal Somers of Teagasc explained the simple basics of good structure and pointed out the ease with which soil breaks apart as a good indicator. Good structure will break apart easily with little force.
Poor structure takes more pressure and will tend to naturally break into big lumps with straight edges, which require more energy to cultivate and, subsequently, consolidate.
The Teagasc men showed examples of both good and poor structure.
Assessing structure in tillage fields is different to grassland, in that it should be done at greater depth and the process is referred to as the double-spade method. Good structure should want to break up like brown bread, while poor structure will just break into smaller lumps.
A further test is to squeeze a lump between the thumb and index finger and see if just a little pressure will cause further breakage.
Questions over sub-soiling
Subsoiling is seen by some as a cure for damaged structure. This is largely because pulling metal through the ground helps remove surface water. But pushing surface water down into the profile may only be moving that water down to a greater depth for bigger problems.
A sub-soiler can be useful if one has a problem at uniform depth and the soil is very dry
David Wall and Brendan Burke of Teagasc had pulled a large five leg sub-soiler through the tillage part of the same field in which the soil pit was located. It had rained the previous night and the surface water had certainly gone down, but it was now down in the channels created by the legs. So solving one problem can often create another.
That said, a sub-soiler can be useful if one has a problem at uniform depth and the soil is very dry.
If the area that needs shattering is damp, it will not shatter and is likely to behave like putty and result in a new smeared layer deeper in the profile.
The summer of 2018 did a huge amount of this work for free
What is needed is for the soil to be shattered both vertically and horizontally to enable water movement and root growth. The closer this can be done to when the roots are actively growing, the better the chance of keeping these cracks open as the roots grow down through them.
The summer of 2018 did a huge amount of this work for free and part of the performance of harvest 2019 may relate to it.
Asked if subsoiling tramlines is a useful operation, the opinion was a cautious “no”.
Where these same tracks are likely to be used year after year, loosening the soil to depth in these areas could well result in a tendency to hold water at a greater depth following loosening. This is not what one wants for tramlines.
The discussion about subsoiling was mainly negative, because of the additional risks involved and the very uncertain yield benefit in most instances. We must always remember that subsoiling does not cure a structure problem, it merely opens up a soil to allow water and air to penetrate to a greater depth.
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