Saturday, 31 December 2011

Getting fed up of sieving the potato bed soil.

  I got a bit fed up of sieving the soil today.  I am mixing in some new horse manure and the pigeon muck as well as sieving out the stones.  The ground has become very wet over the last few days and this means that the soil is a little more reluctant to go through the holes in the bread tray sieve.

It is really time consuming and I am wondering whether to give it up for a while and continue to remove the rest of the stones next autumn.

Sieving is good exercise and produces a very friable soil.  The ground is free of cropping vegetables - the beetroot and the carrots are clamped and the parsnips soon will be.  So, I might as well sieve the soil  now and get it over and done with.

The number of stones that are in this soil is remarkable.  It was replacement soil for contaminated soil that was on my allotment and several others. The new soil was supposed to be top quality organic soil.  I am not sure whether it was organic because it was clay, full of stone and empty of both nutrients and body.  When a soil has no obvious organic matter or small creatures you start to wonder if this soil was treated with chemical fertilisers.  These chemicals will kill off things like worms because there is no organic matter in the soil for them to feed on.

This new soil has reacted really well to the addition of copious amounts of  compost, manure and cultivation.  The soil is finally becoming workable.  I am hoping that cultivating the potatoes will help to break it up  and work in the organic matter a little more.

I took the top off a 210 litre blue plastic butt to make a water barrel.  We have had a lot of rain recently and I am missing collecting it.  The down spout was reinstated - it had fallen off in the wind. I am going to duck tape it to the guttering to secure it and then put a small screw through it.  The down spout is tied in securely with wire.

There were quite a few slugs in my beer traps a few days ago.  I emptied them  into the comfrey butt and replaced the beer.  I looked today but there were no new slugs in the beer.   I am happy about the beer traps being effective.

I put some horse muck on the new sweet pea bed and if I have any left over from the potato bed I will use the left overs on the sweet peas.

Sunday, 25 December 2011

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.

Thursday, 22 December 2011

Heritage or modern seed?

I have bought quite a few seeds from the Real Seeds Catalogue but maybe I should have tried a little harder to buy heritage seeds.

However, if you want disease resistant varieties because you need to grow without pesticides then sometimes you need to compromise.  Also, I want to be able to keep some of my vegetables stored over winter and these good keeping varieties are not necessarily heritage.  Cauliflower: Brassica oleracea botrytis 'Clapton F1 Hybrid'  is a club root resistant variety so I thought that I would try it.  It was also half price in an end of season sale so I could not resist it. (Several others of the F1 seeds were in the sale as well so I got them too)  I have been growing Daucus carota 'Flyaway F1 Hybrid' for years to combat carrot root fly.  This year I am growing Resistafly F1 Hybrid.

The bottom line is to produce some organic carrots to eat. To make this a little more certain I will be growing crops that are resistant to pests.

I would like to believe that heritage plants have a greater affinity for mychorrhizal fungi and grow even better with charcoal but I have not found any significant difference between modern varieties and heritage grown with charcoal.  Both types of plants seem to benefit from the application of inoculated charcoal and  mychorrhiza.  Keeping the old varieties going is more to do with biodiversity than anything else.

I have two dust bins full of marinading lump wood, barbecue charcoal.  The liquid is made up of comfrey, nettle, sweet cicely, worm bin and diluted pigeon manure.  It has been marinading for at least five months now and I will not use it until the spring.  I reckon that will be ample time for the charcoal to take up nutrients.

It will be used on the potatoes first.  I cannot get barbecue charcoal at the moment because there is none in the shops, however I still have the Takesumi charcoal to experiment with.

While some of the old vegetable varieties are better flavoured there are many that are not and they are not so disease resistant either.

Looking around the allotment site people are using the same varieties year after year because they grow well in our allotment soil  with our north facing aspect.  These varieties are more or less the same as I am growing some of which are F1 hybrids. I think that I will continue to buy F1 seed at the moment.

Finally, I have got into growing particular varieties and want to carry on if I can.
This is why I kept some seed in 2011 and I am going to sow it during next season (2012). Seed saving has been quite successful this year so I am going to continue to collect my own seed.  For this I need non F1 hybrids because only these will breed true.  Maybe this is an argument for selecting heritage seeds. So, there are good reasons for getting both F1 hybrids and heritage seed and I will be using both.

Monday, 19 December 2011

Seeds for 2012

These are the seeds that I am going to use in the new year.  Sometimes I like to grow specific varieties so I have bought the seeds from various companies.  Not all the seeds have a cultivar or variety.  There are 64 different kinds of vegetable, herb and soft fruit here.  Some are already in the ground while I am getting very impatient about planting some of the others.

Vegetable Latin Name Cultivar
American land cress Barbarea verna
Asparagus Pea Tetragonolobus purpureus ¬¬¬¬¬¬¬¬¬¬
Basil  Ocimum basilicum Dark Opal
Bay tree Laurus nobilis 
Beetroot Beta vulgaris Boltardy
Beetroot Beta vulgaris Wodan F1 Hybrid
Birds foot trefoil  Lotus corniculatus ¬¬¬¬¬¬¬¬¬¬¬ Just a companion plant
Black berry  Rubus fruticosus  Adrienne
Black currant Ribes nigrum Ben Sarek
Black currant Ribes nigrum Ben Lomond
Borlotti beans Phaseolus vulgaris Cuthbert's
Broad bean Vicia faba Own kept seeds
Broccoli Brassica oleracea Early Purple blend
Broccoli Brassica oleracea Sprouting Redhead
Brussel sprouts Brassica oleracea var. gemmifera  Trafalgar 
Cabbage Brassica oleracea capitata Holand Winter White
Cabbage Brassica oleracea capitata Sherwood
Cabbage Brassica oleracea capitata Golden Acre Primo (II)
Calabrese Brassica oleracea Belstar F1 hybrid
Calabrese Brassica oleracea Green Sprouting
Carrot Daucus carota  Early Nants
Carrot Daucus carota  Resistafly 
Carrot  Daucus carota  Nandor F1 Hybrid
Cauliflower Brassica oleracea botrytis Clapton F1 Hybrid
Cauliflower Brassica  oleracea botrytis Winter Alsmeer
Cauliflower Brassica oleracea botrytis All the year round
Celeriac Apium graveolens rapaceum Monarch
Celery  Apium graveolens var dulce Lanthorn Self Blanching
Celery  Apium graveolens var dulce Full White (Self Blanching)
Celery  Apium graveolens var dulce Granada
Chamomile Anthemis nobilis ¬¬¬¬¬¬¬¬
Chicory Cichorium intybus ¬¬¬¬¬¬¬¬¬¬¬
Courgette Cucurbita pepo ovifera Black Beauty
Cucumber Cucumis sativus Wautoma
Cumin Cuminum cyminum ¬¬¬¬¬¬¬¬¬¬
Dill Anethum gaveolens ¬¬¬¬¬¬¬¬¬¬
Florence fennel Foeniculum vulgare Colossal
French beans Phaseolus vulgaris Own kept seeds 
French climbing bean Phaseolus vulgaris Cherokee Trail of Tears
French climbing bean Phaseolus vulgaris Own kept seeds 'Cobra'
Garlic Allium sativum
Goosberry bush Ribes grossularia Xenia
Grape  Vitis vinifera
Hamburg parsley Petroselinum crispum Berliner
Jerusalem Artichoke Heleanthus tuberosus
Kohlrabi Brassica oleracea caulo-rapa Gigant
Lambs lettuce Valerianalla locusta  Cavallo        
Leek  Allium porrium Oarsman F1 Hybrid
Leek  Allium porrum Mammoth Blanched
Leeks Allium porrum Bleu de Solaise 
Leek  Allium porrum Musselburgh
Lettuce  Lactuca sativa Webbs Wonderful
Marjoram Origanum majorana ¬¬¬¬¬¬¬¬¬¬¬
Mizuna Brassica rapa Waido
Oca Oxalis tuberosum ¬¬¬¬¬¬¬¬
Onion Allium cepa Vision
Onion Allium cepa Ailsa Craig
Allium cepa Mammoth Improved
Onion Allium cepa Bedfordshire Champion
Parcel  Apium graveolens var secalinum ¬¬¬¬¬¬¬¬¬¬¬
Parsnip Pastinaca sativa Tender and True
Pea Pisum sativum Early Onward
Pea Pisum sativum Hurst Green Shaft
Pea  Pisum sativum Onward
Potato Solanum tuberosum Kestrel
Pumpkin Cucurbita pepo  Rouge Vif dEtamps
Radish  Raphanus sativus Cherrybelle
Raspberry Rubus idaeus
Rhubarb  Rheum rhaponticum Champaign 
Rhubarb  Rheum rhaponticum Timperley Early
Rocket Eruca sativa Sweet Oakleaf
Runner beanPhaseolus coccinus Own kept seeds
Sage Salvia officinalis Green Leaved
Salad Burnet Sanguisorba minor ¬¬¬¬¬¬¬¬¬¬¬¬¬
Salsify Tragopogon porrifolius ¬¬¬¬¬¬¬¬¬¬¬¬¬
Scorzonera Scorzonera hispanica Maxima
Shallots Allium ascalonicum Jermore
Spinach Spinacia oleracea Mediana
Spinach Spinacia oleracea Renegade F1 Hybrid
Squash Cucurbita moschata Waltham butternut
Strawberries Fragaria ananassa  Cambridge
Swede Brassica napus napobrassica  Gowrie
Sweet cicely Osmorhiza claytonii ¬¬¬¬¬¬¬¬¬¬¬¬
Sweet corn Zea mays Double Standard
Sweet corn Zea mays Northern Extra Sweet
Sweet pea Lathyrus odoratus Many
Swiss Chard Beta vulgaris subsp. Cicla Galaxy 
Tarragon  Artemisia dracunculoides ¬¬¬¬¬¬¬¬¬¬¬¬¬¬
Tomato Lycopersicon esculentum. Rose de Berne
Tomato Lycopersicon esculentum. Dr Carolyn Pink
Tomato Lycopersicon esculentum. Latah (Bush)
Turnip Brassica  rapa Oasis
Turnip Brassica  rapa Galaxy F1

The allotment plan does not allow for all of these seeds and I will probably be keeping some of them for next year or for later planting.

Vegetables that I have never grown before are Tarragon, Salad Burnet, Dill, Cumin, Asparagus Pea and Parcel.  Now I think that parcel is a bit of a con because it is  celeriac under a different name.  It says  that you eat the petioles and leaves rather than the swollen stem.  Oh well, I'll give it a try.

Getting these latin names right is a pain.  Brussel sprouts in Johnson and Smith's "Plant names simplified" are called Brassica oleracea bullata, while elsewhere they are referred to as Brassica oleracea var. gemmifera.  Now, I would go with bullata because that means bubbles or blisters and is a good description of the buds.  However gemmifera means a similar thing - a plant with stem buds.  The RHS who seem to be the authority on these kinds of names calls Brussel sprouts Brassica oleracea gemmifera so that is what I will do.  I have had the same difficulty with the swede.  It is a type of Brassica napus that colours the fields with yellow in the summer.

I haven't grown celery for a very long time.  It is very demanding of both nutrients and water.  I am going to grow it at the bottom of a trench to see if I can keep it damp enough.  It is also very susceptible to slug damage so I am trying to reduce the slug and snail population now.  This means that there will not be so many next year to reproduce and create a problem.  At the moment I am using beer traps and Ferric phosphate but next year I plan to use a lot more nematodes Phasmarhabditis hermaphorodita to help to keep the slug and snail population down.  

I think that I will have a lovely variety of vegetables next year.  Now all I want is to find some really great recipes for cooking them.

Sunday, 18 December 2011

Keeping sweet pea seeds

This year I have kept a lot of sweet pea seeds and planted them in pots at the end of October.  They have all germinated well. My assumption was that they would not breed true because of cross pollination between varieties that were grown quite close to each other.

However, it seems that  sweet peas are normally self pollinated.  While this may suggest that all sweet pea seeds will breed true, there is some doubt whether this is always the case.  My sweet pea plants were not protected from cross pollination - they were "open pollinated".

Now I had always thought that a bumble bee landing on the keel petals of the flower would make the stamen pop out and coat the underside of the bee with pollen which would then be taken to the next flower.  The fact that the stamen and stigma are protected by the keel petals seems to give the flower more chance of self pollination.  When the flower has gone over, pollen has been shed and fallen on the stigma which does not normally protrude from the petals giving a self pollinated flower.

If the sweet pea is self pollinated then it should be quite easy to keep varieties pure because they would only change by mutation. This might give the opportunity for saving seed with some reliability that doing so would produce the same variety as the parents.
Sweet Pea Stamens
Stamens and stigma of sweet pea Lathyrus odoratus (FCIT)
I'm not so sure and will carefully examine  flowers next year to see if this is true.  Unfortunately, I mixed up all the seeds that I gathered this year so I will get a mixture of colours when I plant them out next year.  

Saturday, 10 December 2011

Planning for (Napomyza) Phytomyza gymnostoma

This is the leek and onion miner fly, which I am battling with on the allotment.  According to the Central Science Laboratory the first record of Phytomyza gymnostoma  in England was in 2003 when the fly was formally identified on allotments around Wolverhampton.  I reckon that it was on my allotment in 1999 at least.  I had decided to give up half of my allotment in 1998 and then used the top bed on the allotment to grow onions.  I remember someone saying my onions look a little worse for wear. The onions were slowly twisting up.

As I am an organic gardener and there is no effective chemical method of combating this little fly anyway, the  way to protect the onions Allium cepa; the leeks Allium porrium and the garlic Allium sativum from Phytomyza gymnostoma is to cover them with a barrier. 

The adult flies are about 3mm long so the mesh of the barrier needs to be finer than this.  There can be no gaps in the barrier and the best way to construct it is with hoops covered with enviromesh netting.

I am using 2.5 metre lengths of 20mm water tubing with a bamboo cane secured along the top to give more stability.  The blue piping is just stuck into the ground.  The enviromesh is stretched over the top of the hoops and the edges are buried in the ground.

This will give a large protected area for the onions and leeks.

The dates that I am going to cover the onions and leeks are March 15th 2012 till May 20th. 2012.   This should cover the time that the adults are flying.  They are probably flying for less time than this but it will ensure that the Alliums are covered for the correct period.  The nets will go back on the leeks on the 1st. of  September 2011 and come off on the 1st of November 2011 when the adults are no longer flying.

There is some evidence that the Larvae, which is 6mm long, can travel through the soil when the Allium plant it is infecting rots away.  Hopefully, burying the enviromesh edges will prevent the Phytomyza gymnostoma larvae from reaching the protected area.

Regardless of how weedy the onions, leeks and garlic get during this period, I will not remove the mesh until the dates listed.  I have seen some people's onions when they have removed the mesh for weeding and it is obvious that the fly has reached the plants.  I will be watering through the mesh.

That's how I am going to deal with Phytomyza gymnostoma.   

Friday, 9 December 2011

Using pigeon manure

I am trying to remove all the large stones from the new potato bed which is quite a chore.  Both the top soil and the subsoil need to be sieved and this is time consuming.  The sieve I am using is the bread tray.  While I am sieving, I am adding pigeon manure; compost; horse manure and sieved turf to the top soil.  

The bread tray sieve
The pigeon manure has a  ratio of 4/2/1 which is fairly good going in the realms of manuring NPK ratios.  Chicken Manure (fresh)   has a NPK ratio of 1.6/1.5/1.0 so pigeon muck compares very well with this.  Now I don't really think that I should give an awful lot of credence to these ratios because I got them from the internet and you should never believe anything you see on the internet.  Having said that,  it does give you a rule of thumb. 

It is obvious from the ammonia smell coming off the pigeon muck that it is very high in nitrogen. And loads of people tell you how good chicken manure is and I agree with them.   So if pigeon muck is like chicken manure,  it will be a valuable addition to the soil.  However, the high levels of nitrogen can damage roots and foliage unless  pigeon muck is added with care.  This is why I am adding the manure now, when there are no plants growing in this soil, so that it can rot down a little more during the winter.  By the time I plant potatoes the concentration of nitrogen should be at a level that will not cause damage. The damage that it causes roots is due to the high concentration of salts in the rhizosphere that cause water to be drawn out of roots desiccating them.  This is what people call burning the roots.     

The various additions to the soil have been really well mixed because of the sieving.  It has also produced a very friable soil.  There is now a good mixture of manure, top soil and compost fairly evenly mixed throughout the soil profile to a depth of about 600mm.  Homogeneity of the soil mixture means that there are no high concentrations of manure in some places while other parts of the soil profile have little or none.  There seems to be more benefit in producing a homogeneous soil, where all plants have equal access to added nutrients and organic matter, than having a patchwork of high and low concentrations of nutrient.  Manure added in the top 300mm of soil is most readily taken up by plant roots so this is where the manure should be mixed in.  However, I am trying to encourage mychorrhizal symbiosis and the fungi will be able to access nutrients below the 300mm depth and be able to transport them to plant roots.

I would have dug deeper but I was digging up the x Cupressocyparis leylandii shreddings that I put in last year as a kind of Hugelkultur.  The whole idea of using shreddings is to provide a sponge for water which will be released slowly throughout the summer.  I didn't really want to damage my sponge by mixing it with topsoil.  

I don't know whether it works but it keeps me happy doing stuff like this.   

I dug right up to the Boltardy Beta vulgaris  so I cannot carry on digging until the beetroot, carrots and parsnips are taken out.  

So to begin the clearance, I harvested Beta vulgaris;  Petroselinum crispum; Tragopogon porrifolius; Scorzonera hispanica;  Daucus carota;  Pastinaca sativa and Oxalis tuberosa.  However, I still have a lot left in the ground.  Who says there is nothing to harvest during the winter? I did not harvest any Allium porrum or Brassica oleracea bullata   mainly because they will stand for a while without deteriorating.  I was also going to get some Eruca sativa but it got too late and dark.  I will have to get some tomorrow.  

Still eating the pumpkin Cucurbita pepo and the Apium graveolens rapaceum  that I harvested earlier in the week.  

I am going to put some of the root vegetables into a box in the shed and cover them with soil.  The rest will be clamped and really I need to get onto doing that quite quickly because we are having the second heavy frost tonight.  

How I make a clamp.
The best way to make a clamp is to put a layer of gravel onto the soil; put the carrots on top with a little top soil to keep them in place;  cover with straw and then cover the straw with top soil.  This keeps them in fairly good nick for most of the winter.  I will probably use them all before the end of the winter though.  I used this method for the parsnips too.  

I am going to try to grow some long carrots next year so I took the bread tray sieve up to the new roots bed and began sieving the top soil.  I want to remove all the stone so that the carrots do not fork.  No fertiliser is being added at all because this may also make the carrot roots fork.  I'm not sure whether this is true but I am not taking any chances.  Really, the soil is in good heart and I don't think that it needs fertiliser.  The carrots are going where the squashes were last year and I added a lot of compost for the squashes.  This should be more than sufficient for the Daucus carota.  

Water from the springs has started to flow down the side of the allotment again so I am going to dig out a new soak away and put in another drainage pipe alongside the allotment.  I am going to put the soak away under the tap path and this will involve lifting two slabs.  Not something that I am looking forward to.  I have not raised these two slabs since I put them down in the 1980s.  It means that there is still some top soil underneath them.  I will use the bread tray to sieve this top soil and put it on the allotment somewhere.  The hole will be filled with stone that I have sieved from the potato bed.

This is a central precept of permaculture:  Always turn an adversity into something positive.  So the stones will be used to make the soak away and the slabs will be put on top.  This means that I will gain some more topsoil and a soakaway. There is no downside.  Second thoughts; it's cold and wet and it was trying to snow today.  That's the downside.
There are some leaves mixed with lawn mowings in the bins by the gate but I have not used any of them yet. 

Friday, 2 December 2011

Takasumi Charcoal

The Takasumi charcoal has arrived in a big box.  I am still thinking about how to use it.

I will be marinading some of it in comfrey liquid but I am thinking of trying some of it neat.  I reckon that it would be more effective if inoculated with nutrients, however I might be wrong.

Lots of the experiments that the commercial firms have done are using pot plants.  What might be illuminating is how it affects containerised tomatoes in the greenhouse.  The conditions there might be a little more homogeneous than outside and the growing medium used could be from the same batch.

This I will do.

Thursday, 1 December 2011

More interest in Biochar and Terra Preta?

It is surprising that the "Allotment and Leisure Gardener" (the NSALG magazine) has an article about biochar in it.  I knew that the Japanese have been using biochar for hundreds of years and that they thought that it had a beneficial effect on plant growth but it does not seem to have been accepted by mainstream gardening until quite recently.

I have been experimenting with inoculated, lump, barbecue charcoal  (i.e. marinaded in comfrey Symphytum x uplandicum; nettle Urtica dioica; sweet cicely Myrrhis odorata and worm bin liquid manure mix.) mixing  mychorrhizal fungi to the dried crushed inoculated charcoal before adding to planting holes and seed drills.
Charcoal marinading in the rich black comfrey liquid mix
Sweet cicely being added to the comfrey bins. It will rot down to
a rich black liquid manure which can be tapped off.
Nettles and comfrey are also added to the bins to rot down
and give a rich black humus rich liquid.

I have convinced myself that this is an effective soil amendment and that plants seem to respond remarkably well to the charcoal especially if growing on poorish soil.

As  German and American research has indicated, the biochar black earths or Terra preta of the Amazonian rain forests are incredibly fertile allowing crops to be grown for millennia while elsewhere in the rainforests crops soon deplete the soil of nutrients.

Experiments with biochar amendments to soil by modern scientists have not shown remarkable differences in the growth of plants because it needs to be inoculated with nutrients.  It does not seem that the Takesumi bamboo charcoal is inoculated with anything.  Whether the "Takesumi"  bamboo biochar is more effective than lump barbecue charcoal remains to be seen.  I would rather use charcoal that has been inoculated and used in conjunction with mychorrhizal fungi because this is what I have found to be effective.  "Carbon Gold" seems to have the same kinds of ingredients that I have been experimenting with so I would expect this to have more of an effect than the "Takesumi".

There is an offer in the NSALG magazine so I will look at the site and see if it is worth getting some and experimenting with it.

Well, as it is 70% off and it is worth having a go with, I am going to get some to see if it is more effective than using the lump charcoal.

There is thought that there may be differences in properties between woods that are used; the temperature it is charred at and the fineness or coarseness of the final crushed charcoal.  Indeed there may be a difference in the properties caused by the materials charred.  Any organic matter can be used to make biochar.  Crop waste such as the stems of sweet corn Zea mays is being used in the USA.  So finding the most efficacious biochar is an ongoing challenge.

My very limited experiments have to be restricted by the time I can devote and the amount of money that I can throw at it.  That is why I am using barbecue charcoal and crushing it with a bull hammer after inoculation.

It may not be the most effective biochar to add to the soil but it works for me.