Raised beds and no dig.

I'm not dead against raised beds or no dig schemes in the allotment.  I just think that permanent raised beds need high inputs of water, fertiliser and organic matter.  They are also time consuming needing a lot of attention to produce high yields from crowded plants.

Putting large amounts of decomposing organic matter on the surface may deplete the top soil of nitrogen.

Even if  you are  a strict recycler, all these things will be dependant on oil; if only due to transporting them.

Also, I can't be doing with all the paths.  I just look at them and think wasted growing space.

There is some thought that walking on the soil destroys its structure.  I cannot for the life of me go along with this.   In any case plants will grow through concrete - how compacted is that? Plants still grew even with dinosaurs compacting the ground.

Plants need water which they obtain from the soil through their roots.  Roots also obtain dissolved nutrients from the soil and they need energy to do this.  To obtain energy they need to respire using oxygen.  This means that plants need both water and oxygen in the soil.  The more fibrous the structure, the better the relationship between these soil constituents.  Walking on soil will squash out some of the air.  Walking across wet  soil will squash out some of the air and fill the pours with water muddying the soil.

However, needs must and sometimes you just have to work the soil in wet weather.  Going over the ground that you have walked on with a fork restores the structure and allows air to enter the ground.  However, common sense says trying to work muddied ground when it is pouring down with rain is pointless.

I would suggest that the structure of the soil is much more dependant on its organic and mineral content than whether it is walked on.  I read somewhere that if you get the calcium and magnesium content of the soil just right you can park you car on the soil and still have a friable soil.  I would like to try this out before I recommend it though - and that will never happen.

So I will continue to use larger areas, wider spacing, less watering and sharp tools to cultivate the soil and produce good harvests.

Having said all this my beds, which are about 15 foot by 25 foot, are all raised above the original ground level. One of the old blokes on the allotment site said why didn't I use old paving slabs on end to keep the soil from falling on the paths and track ways.  This was a good idea and I have, over the years, put paving slabs around most of the beds.

The ground was raised by the addition of lots of organic matter.  It didn't really matter to me what the organic matter was, it still got buried.  I have buried old cotton shirts, leather handbags and shoes;  leather belts; woollen jumpers and socks; tree and shrub shreddings; shredded paper; weeds except for bind weed and mares tail; tree trunks and branches; lots of tree leaves, muck and manures.  I used to bury woollen carpets too until I found they put nasty chemicals on them to prevent them being eaten by moths and fungi.

All these additions to the soil were buried at least two spits down and mostly further than this.  When I dig down now I find nothing except a darker stained subsoil. The nutrients and carbon locked up in the structure of organic material is slowly returned to the soil to increase its fertility.

Apart from vastly improving the drainage of the allotment and enabling me to use the ground year round, the raised bed is like a hot bed.  The decomposing organic matter generates a certain amount of heat and this can warm the soil enabling seeds to germinate earlier - or that is the theory anyway.

To make the raised hot bed, I don't pile organic matter on the top of the soil.  I bury it deep in the soil.  I do this because I do not want it to deplete the top soil nitrogen.  Putting organic matter on the surface of the soil may deplete the soil of nitrogen when it decomposes.  I know there are many benefits of mulching but it needs to be done with understanding and more care than is often suggested.  Piling on mulches is not a magic solution to all your gardening problems.  It is just one more strategy in the armoury of methods you can use on the allotment.

So my beds are raised but they are much bigger than any other raised beds that I have seen.

There is nothing wrong with raised small beds done well but I can't be doing with them.  They are too small for my way of gardening.

And this time of year I just like to go out and dig for an hour or so.  Allotments are not just for growing; they are for fresh air and exercise too.

Just my own thoughts on raised beds and no dig methods.

  I am not really attacking either raised beds or no dig method.  I just cannot for the life of me see why they have become so fashionable.  Both methods involve applying large quantities of organic matter to the soil and this is a fundamental and basic requirement for sustained crop production.

However, adding organic matter does not have to be done in these ways.  There is nothing particularly magical about adding amendments to the soil.  People have been doing this, probably, since agriculture was developed.

I have just heard about the Sinhalese practice of deep trenching and adding any organic matter to the trench before covering with soil and growing crops.  I should not be surprised because it seems that similar methods of growing have developed throughout the world.

Whether you go up; adding organic matter to the surface, or go down; adding organic matter to trenches or even a mixture of both, the common principle of all these methods is adding organic matter.

I dig and I no dig depending upon the needs of the soil.  If the soil has had little organic matter added then I will dig some into the top soil and mulch.  If green manures have been sown in the autumn I will dig them in in the spring.  I will mulch in the summer to conserve water and suppress weeds.  I will do this to produce good crops not because it is a fashion.

I have put concrete slabs on end around the allotment as a retaining wall, not because it is a trend or fashion but because I need to retain my top soil.  The level of the top soil has been raised because I have added so much organic matter.

Another reason, and this is really why I embarked on raising the allotment top soil, was to enable me to drain the soil because it was water logged for most of the winter.

Raised beds are just a waste of time and effort.   There are more paths than growing area.

The gardening philosophy that suggests that soil should not be walked on because it destroys its structure just does not ring true.  I was watching "The Victorian Kitchen Garden" for May on YouTube and the gardeners there were scuffing the ground along the drill lines to consolidate it before raking and making a seed bed.  This is what I was taught to do when I was a lad. It breaks down the large lumps of soil and allows you to make a really good tilth with the rake.

When I was learning how to grow from my grandfather and father they always firmed the soil in seed beds by treading along the rows and raking afterwards.  In this way a really fine tilth could be made fairly quickly.  I still tread along my seed lines to firm the soil before a final rake and taking out the seed drills.  This technique does not seem to prevent the seeds from germinating.

I tread between the rows to hoe and cultivate along the plants.  Removing weeds and scuffing up the soil to slow evaporation seems to be much more important in producing good crops than avoiding compaction.

There are times that I avoid walking on the soil.  When the soil is very wet it can be easily compacted and will form an impenetrable cap on the top soil.  Also when it is frozen, I avoid walking over it.   Otherwise I am constantly walking over the soil.  I do usually scuff it up afterwards but that is just to make the soil look presentable.

So I think that the important thing is to add as much organic matter as possible in as many forms as possible and only use retaining walls to prevent the raised soil from falling onto the paths or to enable drainage.

One of the most enjoyable parts of gardening is to improve the native soil.  Filling raised beds with commercial sterile composts seems to be a complete anathema to organic growing.  These composts are peat based and usually contain inorganic fertilizers.  They will grow some good vegetables for a few years but they are not sustainable.

I will stick to using the native soil adding amendments as they become available.  At the moment I am using home made compost, horse manure, lawn mowings, turfy top soil and shredded branches.

I am also making comfrey, sweet cicely and nettle tea to use as a liquid manure and pigeon manure as a quick acting nitrogen fertilizer.

I am using the charcoal , which in itself is fairly inert , as a method of applying a slow release fertilizer after being inoculated with comfrey tea.  It seems to work for me particularly when I have used mychorrhizal fungi as well.

I must admit I am completely practical about various gardening techniques.  If they work I will keep doing them; if they don't then I will abandon them. The only criterion for success is whether the vegetables cropped well or not.

I do what works for me.

Thoughts on digging or no digging strategies.

I have mixed feelings about this debate.

The modern fashion for using raised beds to grow vegetables can be seen as a method of avoiding digging.  The no dig system seems to have been developed, like so many other gardening techniques, by trial and error.  Then the amateurs that developed it become evangelical and the gullible see it as a some magical method; following the method's disciples' recipes and instructions as if there were no other ways of cultivation.

It is just multiple layers of this and that built up within  planked containers to make  higher than ground level growing areas.  And lots and lots of paths.

I do not think that there is anything magical in the materials that are used to develop these beds.  Indeed filling a raised bed with commercial multi purpose compost or ordinary garden soil seems to get good results.  However, there seems to be a consensus that you start off with a layer of newspaper to suppress weeds and then cover  with compost or other organic material such as straw or hay in layers with some addition of chicken manure.  The layers are built up until the correct height is obtained and a surface layer of compost or soil tops it off.  Certainly it is a very  intensive organic matter form of gardening.  I should be really enthusiastic about this system of growing.

It is a quick and relatively easy way of cultivating an area of weed infested ground because weeds are suppressed by the newspaper in the raised bed and paths are covered in weed suppressing membranes.

It also emphasises the importance of creating and maintaining a high level of soil organisms such as nitrogen fixing bacteria and mychorrhizal fungi.  Again this is something that I agree with and would like to promote on my allotment.

The use of mulches and green manures should enable the beds to reach a high level of fertility and this might be maintained over many years. That is; leaching is reduced and chelating humin, fulvic and humic acids will form complexes that will trap minerals in the soil structure.

Thirdly you do not have to step onto the bed to cultivate it having access from paths constructed around the beds.  This means that the soil is never compacted and is always aerated and well drained.

There is some debate that says that the soil is rarely disturbed in nature and has not evolved to cope with being cultivated to the extent it is on an allotment.

So why am I apprehensive about following the fashion?

I have raised my whole allotment about 600 mm above the original ground level and this does indeed seem to improve the drainage.  However, I have dug down quite deeply too and broken up the subsoil to quite a depth and this might be the main factor in improving the drainage.  Also, I have added a lot of organic matter in the form of logs, branches, leaves and branch shreddings to the subsoil in a kind of Huglekulture and that too might have improved the drainage of the allotment. (Oh yes, and Huglekulture does not have to be constructed on the surface of the soil.)

Adding large amounts of organic matter does seem, anecdotally, to improve the fertility of the soil.  I would conjecture that this is some part due to the provision of carbon for free living nitrogen fixing bacteria such as Azotobacteraceae.  These bacteria are fairly ubiquitous and once they have a carbon source will multiply rapidly whether the organic matter is on the surface or mixed into the top soil.  I doubt very much if digging would severely deplete the numbers of bacteria in the soil especially if it is combined with the addition of organic matter.

I can see that the repeated addition of inorganic fertilizers in place of organic amendments would indeed reduce the number of soil organisms by reducing the amount of carbon available to the heterotrophic soil fauna and flora. However, there are few gardeners now that will use inorganic fertilizer to the extent they were used in the past.  

I would also suggest that a sizeable proportion of soil organisms can survive digging because of their relative size. It is the macro organisms such as worms, soil centipedes, etc. that would indeed be affected by digging. Yet some of these macro organisms may be pathogens and we might want them to be removed from the soil.  Such animals as slugs, snails and pathogenic fungi would fall into this category.  It is noticeable the difference in the number of worms in an undisturbed soil compared with cultivated soil. This is a major disadvantage of digging.  I would suggest though that any cultivated soil would have a reduced number of worms.

In one text book I read recently, there was a chapter on raised bed, no dig growing system giving chapter and verse about how good it was to grow in this way and went on to say that after making a raised bed why not plant green manure to start with...

Now, on several gardening, forums people are going to extraordinary lengths to grow green manure while not digging it into the top soil.  Some suggest strimming and leaving the tops on the surface to rot down or putting a membrane or cardboard over the surface to kill off the green manure.  Others are suggesting that the green manure is hoed off and the tops put onto the compost heap.

I find this incredibly unpractical and self defeating.   The green manure is there to add carbon to the soil in a form that is readily available to microorganisms.  Any nitrogen fixed by legumes will be removed by hoeing off and putting on the compost heap.  Covering or strimming are just adding slug and snail encouraging complexities unnecessarily.

Single digging, slicing off the green manure to put at the bottom of a shallow trench seems to me to be the simplest  and most practical option of mixing the green manure into the soil.

This introduces another important part of using digging as a strategy in the vegetable garden.  Digging done well will mix the soil.  Rotavators do this particularly well.  Any organic matter will be mixed relatively evenly throughout the top soil making it available to organisms throughout the profile.  When it has finally broken down into humus, this will enable chelation and possibly enable plant roots to access the nutrients trapped in it.    There is a great deal of evidence that top soil with large amounts of the black, oily liquid we call humus coating  soil particles is particularly fertile.

Apart from nutrients obtained from decayed organic matter there is also a source of minerals that can be obtained from the break up of stones within the soil by weathering.  I am not sure whether digging can be classified as a weathering factor but other factors such as wind and water seem to have an effect through friction.  I would suggest that digging also breaks up soil minerals by the action of friction releasing nutrients from stones and possibly rocks in the soil.  Digging also exposes the soil to the action of frost and freezing and thawing effects not only breaking up compacted soil but also releasing nutrients from stones in the soil.

There are some times that cropping means that effectively you are digging over the soil.  For example, taking out potatoes.  How on Earth do you do that without digging quite deeply down into the soil?  And then how do you ensure that you have removed all the little potatoes that will undoubtedly survive the winter and begin to grow again right in the middle of another crop and possibly harbour pests and diseases to infect the new years potatoes?  The only way I know is to dig over the potato bed very carefully. The same argument could be put forward for carrots, parsnips and other root vegetables.

There are some that grow potatoes under straw or membranes and harvest from under these.  Well I cannot justify covering the area of potatoes that I grow with membrane or straw for that matter.  Small crops on little beds may make it a little more practical but why add these complexities unnecessarily just so you can say that you don't dig?

The argument that the soil is rarely disturbed in nature is an uniformed view of how nature works.  If you had seem the damage that badgers do to a lawn you would never subscribe to this notion.  Foxes looking for worms on my allotment are continuously digging holes as are cats when they do whopsies.  Take that up to larger animals such as wild boars and deer and we can begin to see that the soil has been continuously turned over and this has happened from the earliest times.  Indeed dinosaurs could make a serious mess of soil structure.  That is why plants called ephemerals evolved; to exploit disturbed ground.  These are plants that we commonly call weeds.

I am really confused about why walking on the soil is such an anathema to no diggers especially as most of the ground in a raised bed system is covered in very compacted, membrane covered, soil paths.

Compaction of the soil is not to be encouraged but I made temporary paths along the sweet pea rows this year compacting the soil quite a lot.  This did not stop the weeds from growing - unfortunately.  Alongside my allotment is the trackway along which cars are continuously being driven up and down.  I mow the trackway regularly to make sure that the weeds do not take over.  Compaction does not seem to have affected the growth of these plants.  There is obviously some relationship between the optimum amount of water and air that should be in the soil and this might be affected by compaction, however to actually squeeze out all the air and water from soil is incredibly difficult - unless you are growing on a clay soil.

I have seen videos on YouTube - old gardening videos where the soil is consolidated by treading along the sowing lines before raking and the drill taken out.    This is what my grandfather and father used to do and I copy them even now when preparing a seed bed.  My seeds still germinate as did my grandfather's and father's.

I do have paths on the allotment; one I made myself and three that were inherited.  After having thought a great deal about them, I dug out the top soil and replaced it with stones covering them with subsoil and putting concrete slabs on top.  This meant that the top soil from under the paths could be added to the growing beds and I would have drainage channels across the allotment under the paths. There is no way I can reach the whole of the beds from the pathways though and I have to tread on the soil to reach their centres.  Does not seem to affect how the plants grow.  If you doubt look at the allotment photographs for April, May, June and July.  I do try to keep off the soil if I possibly can because it makes it easier to work the soil when it is necessary.  I would not like to hoe up the potatoes using compacted soil. But this is all I will concede -  keeping off the soil makes it easier to work

Digging does not prevent you from using green manures and mulches.

I am not rejecting a no dig raised bed system for growing, however I would not advocate that it is the panacea for all growing problems.  There are benefits to digging and sometimes it is the only effective procedure for preparing the soil for crops.  Sometimes, when the soil is clean from the previous crop, the ground will only need hoeing and raking over to make it suitable for the next crop.  I think that this is what I will do after all the brassicas are taken out next spring and I will plant peas and beans in the ground.

So I might be a grumpy old man stuck in my ways and clinging to the past but I see no advantage in making things too complex and creating work for myself.  With the large areas of crops that I grow, I will use the best method of preparing the soil and sometimes that will mean digging.