It has long been my belief - 1

The start of a new topic – a way of introducing new things, and building a knowledge base for those to come. But let me be quite clear here – I am talking about evidence-based observations, not subjective faith in the rightness of my hypotheses. As much as possible this builds on material in my book, though does not necessarily follow any particular section.

I shall start this off with a short discourse on shell energy value and how to make use of it. At more than 19MJ/kg the shell energy value (the SEV to follow the conventions of my book) of black walnut is higher than wood pellets, and the odd handful tossed into the fire-pot of a lit pellet stove has always burned with a good blaze. To avoid the pitfall of having to use energy to pelletize the shell, I asked my student collaborators to a) see what they could do to make cracked shell flow well when in a hopper, and b) how one would have to modify the auger of a pellet stove to adapt it to feeding this modified cracked product. I'm glad to say they've made progress on both fronts, so I'll get them to report on their work.

Shell is approximately 75% or more of the dry weight of the nut, so will always be the largest by-product, by weight or volume. In fact, any production strategy for kernel should build in an energy-based destination for shell. Long gone are the days when it was seen only as an abrasive end-product, or dumped as waste.

Biomass Nut Production in Black Walnut

Well, the book is finally out:
Biomass Nut Production in Black Walnut: Exploring Management
and can be reviewed on and obtained from Lulu

Pruning and felling

Finally getting around to collecting this year’s prunings before the grass gets too high. By my standards I did some severe pruning, and probably raised the lower height of the canopy by an average of at least 30cm!

I also had to cut out two trees which were encroaching on the hydro wires, which allowed me to do something I have wanted to do for a while – relate total subtended branch basal area (their footprint where they join the trunk, if you like) to the tree’s DBH. This is best expressed in the graph, where each point represents a branch plotted against its positional number away from the tree’s tip. There were about 25 branches on each tree.

Why did I want to do this? I have been intrigued for years about the switch from height increase to canopy expansion in open-grown black walnut, as mine are. In their early years the trees ‘concentrate’ on increasing the height of the leading tip. After this period, in an open-grown plantation each branch continues to grow outward and upward, taking some resources from the leader in so doing. With time what I have previously termed the ‘conical growth rule (CGR)’ must break down for the central stem, - DBH continues to jncrease, but as an expression of total canopy subtended rather than vertical height of the leader.

Each tree was just under the 15cm DBH, and I measured both this and the diameter of every subtended branch, working my way up the trunk (though they are plotted numerically in reverse). Height at which they were subtended (where they joined the trunk) was not taken, as there was no apparent relationship here – small branches could be found between larger ones. Hence the dispersion in the graph. Twigs on the trunk only a year old were ignored.

The numbers can be summed up in two ways: either by relating the relative cross-sectional areas (CSA), or by relating the relative perimeters (P; both cumulative in the case of the subtended branches). In both cases both the CSA and P of the subtended portion exceeded that calculated at DBH by between a factor of roughly 2 (CSA) or 6 (P), implying that a switch has indeed occurred. Which measure we use is not important as long as we be consistent. Remember, however, that DBH is measured at a point below the subtended canopy (or almost – the bottom pairs of branches on both trees were still below DBH), so it expresses an integration of accumulation of all biomass above it.

In physiological terms, the tree is growing mostly outwards, somewhere between twice and six times as much as it is growing upwards (a principal leader was still visually detectable on both trees and was not counted). This is in terms of deposition of carbon, the main structural element of the tree. At this DBH or earlier, the CGR is no longer applicable to the central trunk (closed canopy plantations may be the exception) and a ‘subroutine’ needs to be added for the canopy as a whole.

The relationship appears to be quite consistent, though two examples do not make a large sample (for the statisticians among you, the R² value of each line shown was about 0.50). It does seem that this will be the best way of noting when the competitive effect between trees occurs – if the pooled line (pooled because they are so close) does represent more than just these two trees then a change in slope (downwards, or less slope) should infer this, i.e. the branches will not grow so big (their footprints will be less). Variability in footprint under these conditions may be less.

This variability is curious. In open grown conditions the tree may continually be testing the immediate environment, and some of the variability may be due to competition between branches within the tree. This suggests that the leaves must be sensitive to slight differences in light intensity, because the black walnut does not have what might be termed a dense canopy.

Whatever it is, another relationship emerges, and I am again left marveling at the flexibility in expressed life around us (if the trees were closer the expression would be different).

As I walk the walnuts - 10

As I walk the walnuts I reflect on the progress we have made in the last five years and my hopes for this one. All of the technological components are beginning to come together, albeit at different rates, and in spite of glimpses of future bottlenecks that seem to parallel what our climate throws at us, adding to the challenges of nut production so far north, we have the market waiting for what we can supply, so no fears there.

Useful US studies show that we import about $110 m annually of tree nut products from the US alone (the study was commissioned to find this out). I raise gales of laughter when I tell my collaborators that I’d be happy with 1% of that market, but the truth is that if we could achieve a gross return of $25,000 annually to 40 landowners, we’d be well on the road to a sustainable partial livelihood across the region, which is far preferable to one or two producers making greater gains.

But this still requires effort, and perhaps more than we have brought to the task so far. I shall be egging my collaborators on even more, trying to increase the range of skills we bring to the questions that remain, showing why the biological issues of productivity parallel the technological challenges of bringing a product to market. I am more convinced than ever that BNP was, happily, a viable strategy, and that it is easily replicable on a wider scale. But there is a lot of black walnut currently out there on the landscape, and we need to harness this resource, as well, to add to the B of BNP and to our bottom line.

I see as a challenge now, how to add a focus on shell usage as a biofuel. With one of the highest energy densities in natural by-products, and at about 75% of our physical output, shell can be (should be) part of our market strategy, and while I am aware of its usage as an abrasive, amongst other things, in our climate this energy density cries out for a different end-use. We are in the age of renewable energy. Not exploring this would be like throwing the baby out with the bath-water.

As I walk the walnuts – 9

As I walk the walnuts I think about the graying of the population and the fact that the mean age of the attendees at past nut society meetings has been greater than my own, and I am on the cusp of retiring! The fundamental challenge is how to interest young people. The answer, I believe, is only through income potential. Remember that question? Can I make more money from that than from what I’m currently doing?

But perhaps there is another way. And that is to build associations in the mind between nuts and play. To that end, behold the Walnut Express, a model railroad layout that snakes around a peripheral shelf in the cracking shed, ferrying nuts from the Walnut Mountain (or Forest!) to the cracking machine. It’s still under construction so I am not sure whether it’s a Mountain or a Forest, and only time will tell. But one thing of which I am certain – the cracking shed will be a boring place for young people without it. Just ask my grandchildren.

As I walk the walnuts - 8

As I walk the walnuts and look at each tree, it is like a snapshot. Snapshots, by definition, are images captured at an instant in time, and tend to reflect something that we were doing at that given moment. Yet an image of a tree is misleading. It is certainly a snapshot of the tree at that given moment, but the tree is the ultimate interpolator, the summer-up of expression over its lifetime, the presenter of the all-gone-before. A tree, then, while in the present, is all of the past, as interpreted by its individual genome in that unique environment.

I say this because a tree is a prisoner of its roadmap for fixing and depositing carbon, and, once started, it cannot deviate from this roadmap. Oh, the roadmap may be altered for it – spring frost effects on bud growth, branch removal by pruning - but a black walnut always looks like a black walnut, no matter its shape, and will always yield nuts, not acorns.

With time I am less involved with the form my trees take. I matched their early growth with my own energy, interfering according to my criteria at the time, but now am content to let the trees fill their space however they will, their response to that interference an acknowledgement of my then-presence on the landscape, an element of biodiversity as ephemeral perhaps as the guarantee that the snow buntings will return every year. Nothing is guaranteed, not even that the energy to interfere goes undiminished, but I prefer to think that I just understand myself better now, and that however the trees fill that space is the way it should be.

Nuts aweigh

Six months without a word. I should apologize. 2009 went down in the yearbooks as nutless, so I hibernated. Things have not been static, however. The continuous-flow walnut washer joined the suite of black walnut technologies on the farm, and through the efforts of my good friend Rod enough walnuts found their way to the farm back in November for the washer to be given a trial run. Rod also asked me some penetrating questions, so rather than repeating everything here, follow this link to Rod’s blog and photos of the washer in action.

http://rodcroskery.wordpress.com/2009/11/09/a-visit-to-lostwithiel-farm/