Biochar Experiment (2)

The biochar samples arrived from Oxford Biochar (Biochar Experiment). What we are required to do is to grow a crop of our own choice in two adjacent square metres of soil, identical except that one of the two mini-plots has biochar added. Today I have prepared two beds on part of one of my new raised beds and added the biochar to one of them. Although I won't be planting for a few weeks yet, by preparing them now I am giving the biochar a chance to be 'primed' by the soil organisms and the compost that I added (to both plots to maintain equality). Oxford Biochar didn't indicate if their material has gone through any priming process. When I submit my results I'll make sure that I record the length of time the biochar has been in the soil prior to planting. I know from reading about other biochar experiments that sometimes results which show no positive, or even negative results, from biochar application are explained by the fact that 'fresh' biochar has been used.

The application rate recommended by Oxford Biochar is 1.5Kg (the bag you see in the picture) per sq. metre. That is the equivalent of about 6 tonnes to the acre (15 tonnes/hectare)and is at the mid to lower end of recommended agricultural application rates, certainly not excessive.

With reasonable care taken to ensure that the soil and growing conditions of the two plots are comparable, it is reasonable to assume that any significant differences in crops yields will be because of the biochar. However, assuming there is a difference, there remains the problem of identifying which characteristics of biochar are responsible for the variation. In itself it has no nutrient value but one or more of its physical characteristics may increase my yields:

• There could be a rise in PH. This could be marginally helpful for some crops but my PH is generally OK for most things I am likely to grow.
• Biochar can help with drainage on sticky soils but my raised beds are fine in that respect.
• On the other hand they can also help retain moisture. In a dry summer that could be helpful.

You can begin to see how biochar's effect are most pronounced on degraded soil or those which suffer from a particular negative characteristic. On these criteria I can't imagine a dramatic effect but biochar's trump cards are:

• an ability to store nutrients in its maze of microscopic channels
• encouragement of microbial and fungal activity leading to
• increased availabity of Ca, Mg, P, and K

If I do see growth differences in this experiment I expect that it will be these latter characteristics which will be at work. I'll have to wait and see but there is one observable characteristic of biochar which is immediately obvious - the albedo effect. I hope you see in this picture (click to enlarge) how the biochar, although mixed into the soil, has left enough on the surface to darken it. My soil is a dark loam anyway but the additional darkening affect should retain that little bit more heat, valuable at this time of year as the soils struggles to heat up.

Of course there is one more important variable - what to grow! I might try to squeeze as much as possible from the experiment and plant to different veg, perhaps a root crop and something leafy. Carrots and lettuce?

Saturday, Seaweed and a Flurry of Snow

These past few days here in the North-East of Scotland we've had a bit of weather reversal with our English neighbours. Usually we are colder but while England has been coping with freezing rain and records lows we've had some balmy days. Is 11ºC (52ºF) balmy? From where you're sitting maybe not, but for us in February it's almost enough to tempt you to indulge in a frenzy of planting. Bad mistake, which I resisted because I am surrounded by old hands who have seen more snow falls in April than snowdrops in January and who are guided by dates not ephemeral warm spells. If global warming is kicking in these guys will need 20 years solid data before they'll plant their early tatties before the end of March.

So instead of premature outdoor planting I took advantage of a calm day, a warm sun and a tide which had left an offering on the strandline to collect some seaweed. The shore is a five minute stroll with the wheelbarrow.

You can see the line of seaweed deposited by the tide. Note the prolific growth nearer the low tide mark but this is growing, anchored seaweed which I wouldn't take. In fact I think it might be illegal. Few moral dilemmas though when I could have filled my barrow many more time from the strandline but I am reminded by Gardenzine that '. . . seaweed that is left behind when the tide retreats will be returned to the sea at high tide. In the meantime, it is providing shelter for hundreds of creatures and protecting them from dehydration until the sea picks them up again. Pick seaweed that has been pushed beyond the reach of the tide or has been washed up by storms and wash the seaweed in the sea if you can to allow any sea-dwelling creatures sheltering there to escape.'

The view is looking back upstream to the harbour but it's also the outfall for the River Dee and so although this is tidal there's a huge volume of fresh water passing this point too. That makes me think that the seaweed I am gathering may be lower in salt. Advice seems to vary about whether seaweed needs to be 'washed' before using. I'll take a chance with my composted, 'lo-salt' harvest which I'm using here to top off a compost bin.

I don't have to be convinced of the value of seaweed but I was intrigued to read, again in Gardenzine, that some bloggers complain that the flavour of Ayshire's famous potatoes has declined since a lack of available labour to cart seaweed on to the potato fields has meant that this traditional fertiliser is no longer used. More pejoratively, it was seaweed that underpinned so-called 'lazy-bed' agriculture in Ireland and the West coast of Scotland where the low fertility of peat-based soils were supplemented by the nutrients supplied by spread seaweed. The term lazy-bed seems unfair both to the crofters and the seaweed as it was probably the most productive solution to a poor soil and an easily available resource. And I know that even with my relative proximity to the source, carting seaweed from the shore to the land is not for the lazy.

With the harvest put to bed in the compost heap and given its covering blanket the sun disappeared in a darkening sky and a few snow flakes flurried in a bitter wind. The seasonal temperatures had returned. The tools went back in the shed and I was pleased to have kept the seeds in their packets for the time being.

Gaining An Edge - Small Increment No. 1

OK, it's not a brilliant drawing, I concede. Let me explain.

I doubt if any of us have a garden or allotment which is perfect in every respect. We all have to work round limitations of one kind or another - soil, aspect, shading, wind, temperature, builders' rubble. Your gardening limitation is the biological equivalent of the slowest ship in a convoy. What is slowing you down? For me, I know it's not the soil - deep, free-draining in the raised beds, reasonable PH. But give me a longer a season and another 5° on average temperature and I'm sure I could double the yield I'm expecting.

Some things we have to accept; others we can squeeze a little.

Things I Have To Accept No. 1 Daylight hours on 22 December (shortest day) amount to 6 hours 40 minutes

Things I Have To Accept No. 2 My plot is on a north-facing slope.

Things I Have To Accept No. 3 Average annual temperature 7.9 °C (46 °F).

What this means is that the long winters, amplified for me by the hill to the south shielding an already low sun, causes the soil to warm very, very slowly in spring, late frosts can wipe out early plantings and even when summer does come higher temperatures are elusive. What I have to do is find ways to extend the season by using all the tricks that I can to squeeze a little here, a little here...

Small Increment No. 1: level the soil So back to my 'graphical representation'. What is happening here is that by making the soil in the raised beds level, rather than following the natural slope, I've increased the angle that the sun hits the soil from 20° to 30°. Joy Larkcom, in her inspiring Grow Your Own Vegetables quotes research that suggests that a 5° gain in slope is equivalent to moving 30 miles to the south. On that basis, my raised beds at least, if not my rhubarb languishing on my un-levelled border, have moved to Dundee with their 10° gain. (Perhaps by creating 10° south-facing slopes in the raised beds they could be in Edinburgh.)

More Small Increments to follow. Dundee is only the first stop!

Received Wisdom - Apply in Small Quantities Only

There's plenty still to do at the lottie. But biting winds some days, frozen soil others, are slowing me down. It does give me the chance to some reading though. I'm not a scientist but enjoy reading explanations by scientists or experts in a particular field about how things work, or, in the case of soil and growing healthy plants, what exactly is happening at the microscopic level and what we do can encourage natural processes to function most effectively.

Of course, you have to choose your sources carefully and, for me, approach every explanation and piece of advice with a healthy dose of scepticism. I'm old enough to have seen scores of 'facts' in the fields of nutrition, health, medicine and plant husbandry proved wrong. Most of us now accept that: blood-letting is not a cure for illness; formula milk is not better than breast milk for babies; homosexuality is not a disease. Too obvious? How about: margarine is not better than butter for your health; having high cholesterol is not a reason for not eating eggs; chocolate does not cause acne. But in farming and gardening, despite some progress in some countries towards the recognition that organic systems are good both for the environment and personal health, many millions of growers world-wide are still being duped by powerful forces to believe that inorganic nutrients added in liquid or granular forms combined with remedial use of herbicides, insecticides and fungicides are a legitimate and sustainable way to grow crops.

But it is precisely because I know how easy it is to persuade when the listener is sympathetic to the argument that when I read about organic growing I don't necessarily want my beliefs to be re-enforced, I want them to be challenged. It is just as possible for 'received wisdom' which is actually nonsense to be handed down as fact in the organic world as it is in the non-organic arena (still chitting potatoes? - maybe wasting your time!). That is why I relish the two papers, both available free online, which I have been absorbed in these last few days. Both, in different ways, have challenging things to say about compost and its value. Both are written by people who are undisputedly supporters of organic systems so I don't doubt their credibility on that score and I am prepared to respect their viewpoint and listen to what they say. I know that both will make me think harder about the complex biology of living soil systems.

Can You Have Too Much Compost?

The first is Steve Solomon's Organic Gardener's Composting. It covers the basics - how to make compost, building heaps, materials - but in great and fascinating detail, and he talks knowledgeably about historical aspects, vermicompost and the vital role of humus in the soil. But for me it gets particularly interesting when he develops a theme with the following prelude: 'Encouraged by a mistaken belief that the more organic matter the healthier, they [home and market gardeners] enrich their soil far beyond any natural capacity. Often this is called "building up the soil." But increasing organic matter in gardens well above a climax ecology level does not further increase the nutritional value of vegetables and in many circumstances will decrease their value markedly.' Talking to puzzled gardeners who came to his talks with tales of disappointing yields, Solomon writes: 'Mr. Organic owned a pickup and loved to haul organic matter and to make and spread compost. His soil was full of worms and had a remarkably high humus level but still did not grow great crops.' and 'In Organic Gardening magazine and Rodale garden books we read eulogies to soils that are so high in humus and so laced with earthworms that one can easily shove their arm into the soft earth elbow deep but must yank it out fast before all the hairs have been chewed off by worms.'

What is the rationale behind Steve Solomon’s belief in the limitations of composting? This links to Chapter 1 of his paper but the challenging material is in Chapter Eight.

Too much of a good thing?

Is It Minerals We Need?

The second heretical paper is Better than Organic - a Conversation with Agricola, by Michael Astera. Astera develops his argument in the context of a supposed interview with one Agricola, not I think the Roman general who conquered Great Britain, but the German scientist Georgius Agricola who is known as the father of mineralogy. This is the clue to Astera's belief that most of the world's farmed land requires re-mineralisation after centuries of depletion. The first question in the interview goes as follows:

Q. You were saying Organic farming and gardening aren’t really working. How are they not working?

Agricola: 'They’re not working on several levels, including corporate greed, business ethics, and of course “We’re from the government and we’re here to help you.” But that’s not what I’d like to talk about today. I’d like to focus on the nutrition aspect, and on soil, plant, and animal health. Specifically, why most Organic food isn’t necessarily more nutritious than chemically grown food.'

Don't let that put you off! It is in essence an argument which points to the futility of adding compost to soils which are minerally deficit but he is a friend of organics and as he develops his theme you begin to be intrigued by his logic (and then maybe go out and buy some rock dust). First is a fascinating review of the writing and research of the early proponents of organic systems. Follow the link at the end of Part 1 to get to the essence of his argument in Part 2

I need to get my soil in such a condition that I can plunge my arm in up to the elbow and risk having my hairs ripped off by earthworms before I can feel able to question the value of compost but while I'm waiting for my humus and worm population to build up I'm quite happy to read this kind of stuff. I might even be able to have my own opinion one day!

Biochar Experiment

An email arrived this week from a company called Oxford Biochar. I had forgotten that some time ago I volunteered to take part in a biochar trial. They tell me they are posting out the kits and instructions very shortly. Few details yet of what is expected of us but I am pleased to get the chance to be involved in a trial of this kind.

Most people who are likely to come across this blog will be aware of biochar and what is claimed of it. Fewer, I imagine, will be using it or have any experience with it. I don't want to run through the whole history, the claims of its proponents or the scepticism of its detractors. (Some of the most informative sources I have come across about biochar are listed here.) But when you have lots of noise and little action, there is nothing better than getting your hands dirty to help provide some evidence.

It seems to me there are two distinct sets of criteria to consider when using biochar. The first is strictly from a gardening viewpoint: is it effective in conditioning soil and enhancing plant growth in organic systems? Under this heading we might include: improved moisture retention, reduced soil acidity, reduced leaching of nutrients, reduced fertiliser requirement, increased availability of nutrients and so on. The second aspect is biochar's potential for carbon sequestration. Under this heading we might include: projected contribution to reduction of global carbon emissions; the economics and environmental aspects of biochar production; stoves, methods of pyrolysis, gasification and recoverable energy, and so on.

If positive conclusions can be arrived for both aspects - then it seems we are on a winner. Can it be a solution to global warming and boost our productivity in organic systems? Many say so but some biochar growing trials are inconclusive or report negative results. And what if governments thought it would be a good idea to give subsidies to farmers to grow crops for turning into charcoal instead of feeding people?. Biofuel seemed a good idea when it was made from the waste from sugar plantations in Brazil but not so clever when the economics made it profitable to use the whole plant and not just the waste.

Important as the second question is, it is the experience of gardeners and farmers that can shed light on the first question. Can we replicate the presumed benefits of the terra preta soils of Brazil? Do improvements in plant productivity only occur on poor-quality soils? To what extent does biochar have to be 'primed' before using? What differences are produced in biochars by varying the temperature of pyrolysis? To what extent does the nature of the source material effect the action and qualities of the end product?

When my package arrives from Oxford Biochar it may just be a small bag of charcoal, a few seeds and an instruction sheet. But even with those modest assets I hope to make a small contribution to a field with many questions and few answers so far. I'll be recording my progress with the experiment on the blog. Please follow!

Screen grab from Oxford Biochar video

Chilly Chillies

It's strange but comforting to think of fiery chillies when icy blasts are rattling the windows. But I am already anticipating my bountiful crop with the arrival of a seed order from Tamar Organics including 30 seeds of my chosen chilli. Last year, pre-allotment and gardenless, the only thing I grew apart from my the solitary potato( Picking Potatoes), was window-sill chillies. Then I chose, without much planning, Early Jalapeno. It's the variety widely grown in Mexico for using with nachos and globally on pizzas.

For me it was a bit disappointing on two counts. It germinated very well, so well in fact I had to give lots of plants away to friends and relatives who helped with the feedback. But the general opinion? - Not very productive, and not enough heat. The mildness must have been something to do with the growing conditions because it is described as moderately hot. So I have promised my brother-in-law, who could eat a whole plant's harvest at one sitting, that I would try and give him something this year that would give him more capsaicin to chew on.

From many possibilities I have chosen a variety called Barak. It is described as producing'extremely hot small bullet shaped fruits produced in very large numbers'. It's a Purira type chilli and this variety matures to red from green purple and other hues making it very decorative. On the Scoville scale it's rated 8, or a tongue numbing 50,000 units. This year I won't have to block off all the incoming light into my flat with chilli plants as I have the greenhouse at the allotment and the extra light and heat may produce better, hotter fruits.

Here's part of last year's crop, well, actually, if I'm honest, nearly all of it, at least from the plants grown by me. (My mother's 8 chillies from her single plant beat my best one!)

Comments and advice on this year's selection appreciated! If it's a good one it will be a) beautiful, b) very productive, c) very hot (really just a variation on productivity as you use less) and d) perhaps will taste nice if not just pure heat. Progress reports guaranteed. Sample chillies posted on request (harvest permitting.)

Are Your Nodules Pink?

After my last post I started worrying about my beans' roots' relationships. In the sub-soil chaos would they find the symbiotic relationship they craved? Would Mr. Bean find the perfect Ms. Rhizobia for nurturing nitrogen together? The simplest way to find out is to have a look. And here is the root system of one of the beans. You can see the nitrogen-fixing nodules quite clearly (click to enlarge) although I'm not sure there are as many as I have seen in other situations.

You'd think that with the evidence of obvious nodules I could relax. But it seems it's not quite as simple as that. The presence of nodules does not in itself mean that significant nitrogen fixation is taking place.' When nodules are young and not yet fixing nitrogen, they are usually white or gray inside. As nodules grow in size, they gradually turn pink or reddish in color, indicating nitrogen fixation has started.' In fact the reddishness is caused by a protein similar to the haemoglobin in our blood and performing a similar function in managing oxygen flow to the bacteria. Apart from immaturity there are two main reasons why the nodules would not be pink inside. One is if the plant has reached the fruiting stage in its development. Its whole purpose in developing the relationship with the symbionts has been to store nitrogen to utilise in the formation of its seeds. That's why green manures are cut down before flowering. Leave too late and the nitrogen is no longer in the ground. The other reason for half-hearted nodule formation and colouring is simply that if the plant can access available nitrogen in the soil it will not invest energy is cooperating with the nitrogen-fixing Rhizobia. (It costs a significant amount of photosynthetic effort to sustain the bacteria.) So in an already nitrogen rich soil, don't expect legumes to add to that store - they will use it instead.

And so it's time for the crucial test of my nodules. It was almost painful slicing them with the craft knife to reveal the internal hue of - green?? 'Legume nodules that are no longer fixing nitrogen usually turn green and may actually be discarded by the plant.' Here's my take on what happened. Until the gales, my beans were growing vigorously and looked very healthy. I'm sure had I looked then my nodules would have been nice and pink. After the storm which flattened them, perhaps they were so shocked that the available nitrogen quickly got used up in trying to repair torn tissue. I'm wondering too at what temperature nitrogen-fixation switches off, if at all. Current soil temperature at depth of 4" (10 cms.) is about 4C.

As usual, I come to no serious conclusion. More questions raised than answered. Will the relationship warm up with the weather? Watch this space. Thanks to W.C. Lindemann and C.R. Glover of Mexico State University for background info:Nitrogen Fixation by Legumes