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I was intrigued to read that ploughing causes the loss of Potassium from the soil - necessitating the use of fertilisers. (Natures Building Blocks - Oxford University Press).
I then went on to find several references to the destructive properties of ploughing from Wikipedia
"Problems with mouldboard ploughing
Mouldboard ploughing has become increasingly recognized as a highly destructive farming practice with the possibility of rapidly depleting soil resources. In the short term, however, it can be successful, hence the reason it was practised for such a long time. A field that is mouldboarded once will generally have an extraordinary one time yield as the larvae of pests and seed from weeds are buried too deeply to survive. After the first harvest, however, continued mouldboarding will diminish yields greatly.
The diminishing returns of mouldboard ploughing can be attributed to a number of side effects of the practice:-
Foremost is the formation of hardpan, or the calcification of the sub layer of soil. In some areas, hardpan could once be found so thick it could not be broken up with a pickaxe. The only effective means of removing hardpan is using a "ripper", or chisel plow, which is pulled through the hardpan by an extremely powerful and costly tractor. Obviously, this layer eventually becomes impenetrable to the roots of plants and restricts growth and yields. This layer also becomes impenetrable to water, leading to flooding and the drowning of crops.
Mouldboard ploughing rapidly depletes the organic matter content of soil and promotes erosion; these two problems go hand in hand. As soil is brought to the surface, the root structure of the previous harvest is broken up, and the natural adhesion of soil particles is also lost; though loose soil appears good for plant germination (and it is), this loose soil without cohesion is highly susceptible to erosion, multiplying the rate of erosion by several factors compared to a non-mouldboarded plot. This increased rate of erosion will not only outpace the rate of soil genesis but also the replacement rate for organics in the soil, thus depleting the soil more rapidly than normal.
Mouldboard ploughing leads to increased soil compaction and loss of pore space within the soil. Soil is a bit like a bucket full of balls filled with sand. Each ball represents a cohesive particle of soil, and when stacked the balls leave a great deal of air space, required for healthy root growth and proper drainage. Mouldboarding so disturbs the soil that it breaks these balls and releases their contents. When this happens, the much smaller particles that are within the larger particles are released and pore space diminishes, leading to hard compacted soil that floods easily and restricts root growth.
[edit] Soil erosion
One negative effect of plowing is to dramatically increase the rate of soil erosion, both by wind and water, where soil is moved elsewhere on land or deposited in bodies of water, such as the oceans. Plowing is thought to be a contributing factor to the Dust Bowl in the US in the 1930s. Alternatives to plowing, such as the no till method, have the potential to limit damage while still allowing farming."
It made me think twice about turf stripping and double digging. In turning a patch of the grass (polytunnel) back into a veg patch I have tried to retain as much of the topsoil as possible. I will however need to add a lot of compost and manure to compensate.
Should we really be breaking up the soil as much as we are? I have a hand tiller (?) from Lidl which goes down 10cm or so. Is that doing damage to the topsoil by breaking it up too much.
I then went on to find several references to the destructive properties of ploughing from Wikipedia
"Problems with mouldboard ploughing
Mouldboard ploughing has become increasingly recognized as a highly destructive farming practice with the possibility of rapidly depleting soil resources. In the short term, however, it can be successful, hence the reason it was practised for such a long time. A field that is mouldboarded once will generally have an extraordinary one time yield as the larvae of pests and seed from weeds are buried too deeply to survive. After the first harvest, however, continued mouldboarding will diminish yields greatly.
The diminishing returns of mouldboard ploughing can be attributed to a number of side effects of the practice:-
Foremost is the formation of hardpan, or the calcification of the sub layer of soil. In some areas, hardpan could once be found so thick it could not be broken up with a pickaxe. The only effective means of removing hardpan is using a "ripper", or chisel plow, which is pulled through the hardpan by an extremely powerful and costly tractor. Obviously, this layer eventually becomes impenetrable to the roots of plants and restricts growth and yields. This layer also becomes impenetrable to water, leading to flooding and the drowning of crops.
Mouldboard ploughing rapidly depletes the organic matter content of soil and promotes erosion; these two problems go hand in hand. As soil is brought to the surface, the root structure of the previous harvest is broken up, and the natural adhesion of soil particles is also lost; though loose soil appears good for plant germination (and it is), this loose soil without cohesion is highly susceptible to erosion, multiplying the rate of erosion by several factors compared to a non-mouldboarded plot. This increased rate of erosion will not only outpace the rate of soil genesis but also the replacement rate for organics in the soil, thus depleting the soil more rapidly than normal.
Mouldboard ploughing leads to increased soil compaction and loss of pore space within the soil. Soil is a bit like a bucket full of balls filled with sand. Each ball represents a cohesive particle of soil, and when stacked the balls leave a great deal of air space, required for healthy root growth and proper drainage. Mouldboarding so disturbs the soil that it breaks these balls and releases their contents. When this happens, the much smaller particles that are within the larger particles are released and pore space diminishes, leading to hard compacted soil that floods easily and restricts root growth.
[edit] Soil erosion
One negative effect of plowing is to dramatically increase the rate of soil erosion, both by wind and water, where soil is moved elsewhere on land or deposited in bodies of water, such as the oceans. Plowing is thought to be a contributing factor to the Dust Bowl in the US in the 1930s. Alternatives to plowing, such as the no till method, have the potential to limit damage while still allowing farming."
It made me think twice about turf stripping and double digging. In turning a patch of the grass (polytunnel) back into a veg patch I have tried to retain as much of the topsoil as possible. I will however need to add a lot of compost and manure to compensate.
Should we really be breaking up the soil as much as we are? I have a hand tiller (?) from Lidl which goes down 10cm or so. Is that doing damage to the topsoil by breaking it up too much.
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