Sunday, 2 April 2017

Week 26: (27th March to 2nd April 2017) or "Fieldwork 'Site'-seeing tour"

A few metres away from where I tap little black squares, sowing letters into words, is a large wooden table. It sits opposite my kitchenette. Taking temporary residence upon it is the most significant ingredient for any kitchen. Without a doubt, it is the most fundamental virtue of any recipe, be it chestnut veloute, bresse duck or prune soufflé. No chef could sport a hairnet without realizing the incalculable and salient contribution this ingredient has made to their menu. In many ways, it is too special for the Specials Board!

And yet, despite its prominence in nearly every recipe, few - if any - kitchen cupboards stock this valuable ingredient. It's does not get inked onto shopping pads nor does it sit in aisles waiting to be hurled into metal trolleys. It does not tantalize the taste-buds nor remedy a hungry stomach. In spite of this, it remains the most critical component of any culinary concoction. It is one of the seminal ingredients for the recipe of life. I would live unhappily without steak. However, I would not live at all without this one, cardinal ingredient.

Deceptive readers may have already guessed the important facet that currently occupies my kitchen table. It is, of course, soil; the womb from which every foodstuff, every recipe, and every dish is born. Few items are boiled, sizzled or fried without having experienced the brown vaults of goodness that lie await in the soil. For most of their lifespan, the soil is a nutrient-rich blessing to the root vegetable; a line of defence against the daily torment inflicted by local bunnies. But perhaps a question is still yet to be answered: why do I have soil all over my kitchen table?

I am relieved to quash any lingering curiosity or concern. Many, I expect, may be starting to wonder (or fear) that this soil is part of some new home-grown food business, or perhaps a way of reducing food miles to food inches. (If only the great catalogue of flavours could be cultivated from a small plot on a kitchen table!) No, the soil on my table is the evidence of a week of both hard work and field work.

It is also evidence for a wonderful journey.


There are many lanes in the backyards of England which appear to transcend the constraints of space and time and exist solely as vestiges of some distant past or the shadows of a great idea. To many, the hollow tree-lined tunnels that weave through the countryside do not exist at all until the moment your tyres roll through them. They are so pristine, so unsullied, so unhinged from the world of technology, that you cannot help but wonder how these lanes possibly link up to a world of civilisation. You would not be surprised to turn around the bend and find the lane is still being built ahead of you. Neither would it surprise you to turn around to see the road dissolving back into the green glory of the English countryside. As a young boy, growing up on similar tracks, I became enchanted by these single-lane passages; paths upon which one could cycle along for two, three, five miles without so much as a glimpse at accompanying traffic. But then, along these great grassy alleys of wonder, traffic does not exist. Quite simply, it's just you, sandwiched between the hedges, enveloped by the trees, slipping deeper and deeper into the great hush, as you pursue a course through the corridors of wonder and mystery, ushered along by an unspoken tranquillity.

I write having spent the best part of the week roaming through these tender passages. They do feel tender and I often felt that the great van upon which I was travelling was too ferocious for these dainty lanes. How more appropriate it would have been, had I been perched on a pew in a horse-drawn cart! Alas, I was on a mission to visit five of my study sites and had only three days to negotiate 300 miles, through Somerset, South Wales, Herefordshire and Shropshire. I was also hauling a considerable amount of fieldwork equipment, and having struggled with carrying it a few hundred yards, I could not conceivably put any poor, unsuspecting mammal through that burden, however disaffected it might have appeared.

The task was simple. I would visit my sites, collect samples of soil down to the bedrock and extract a sample of saprolite (weathered bedrock) which, effectively, is the material that I'm most interested in. For a Soil Scientist to admit that the most valuable material is not soil, and instead it is the weathered rock - in this case, sandstone - directly below it, is perhaps ruffling the feathers of a scandal. But, I must retaliate; the soil is formed from this weathered rock! Thus, my visit was a 'quick check' (otherwise, more technically known as a reconnaissance survey) to see whether my sites would be suitable. It was a 'site-seeing' tour.


Allow me to introduce Dr Andy Tye, from the British Geological Survey. I have very few photographs of Andy without the hand auger that he so effortlessly corkscrewed into sandy, silty and clayey underworlds. That's perhaps explained by the fact that he seemed so naturally fond of the task! I took over the auguring for less than five minutes before the apparatus was repossessed. This was to some relief, given the fact that some soil profiles are extremely difficult to drill through.

At each revolution of the auger, a column of soil is displaced from its position and becomes trapped in the blade. It is then carefully lifted out of the hole and placed onto a plastic sheet or mat. The process then takes place again, until you find that the auger is not drilling any deeper. That then is a signal that you have reached the saprolite! It is generally good practice to photograph the soil on this sheet, before sub-sampling some of the material into bags for further analysis. Some profiles revealed very interesting colouration changes; these are known as horizons in the trade.



What can one learn from the soil in the field? The answer is: quite a lot. Pedologists rarely need to employ expensive, time-consuming laboratory missions to describe the soil they have extracted. Many of the key variables can be ascertained by a quick 'finger' test, in the field. The next time you're engaged on a Sunday stroll across the fields, take five minutes to rest the legs, and perch down on the ridge and furrows. Take a handful of soil. The following procedure is, I admit, moderately dirty but assuredly great fun if one executes it with an open mind.

So, with your handful of soil, pour water droplets over it, without it becoming too wet. (It's a trial-and-error process). I am also assuming, here, that you have a bottle of water in your possession. If not, make it a priority to take a bottle on your next stroll. Those who have water to hand, pour it as instructed and start to form a ball with the soil. It will begin to feel like moist putty. Next, try to squeeze the ball. If it collapses under the stress, the soil is most likely to be described as a sand; in other words, the soil is comprised of a majority of sand-sized particles. If the ball remains in tact, place it between the thumb and the forefinger and gently squeeze it into a ribbon. Before too long, the ribbon will break, but that is okay, as it is the length of ribbon which we are interested in. (I'm also assuming you're still interested). A small ribbon of less than 2.5cm is likely to be a loam; if it feels smooth, it's a silty loam, if it's gritty, call it a sandy loam. A strong ribbon that extends beyond 5cm is likely to be a clay. Once again, if it feels smooth, it's a silty clay; if it's gritty, it's a sandy clay.


Take another handful of soil. How is it structured? Is it structured? Can soil ever be structured?

Soils are often structured into aggregates; lumps of soil particles which, given enough force, can often be broken down into smaller clusters. Some soils are finely aggregated, with aggregates seldom exceeding 6mm in diameter. Some are very coarsely structured, with clumps measuring up to 50mm! Soil structure was once described as "the architecture of the soil" by Sir John Russell, and indeed, it is one of the most essential properties. I have a nice book, written by Tom Batey, that was given to me once. Inside is a nice analogy of soil structure:

"Just as a building consists of rooms, corridors, a framework to provide stability, a roof to protect the upper surface and coatings to prevent deterioration, the physical construction of a soil possesses equivalent components. The primary building materials in the soil consist of mineral particles, ranging in size from stones to sand and clay. Organic products and clay bind the larger particles together...If a building is hit by a large force, it can be reduced to rubble and dust and so can a soil."

Another technique equally easy to accomplish in the field is an assessment of soil colour. Often, this attribute is given a hard press, but it can provide a crude idea about the state of the soil. A soil that is particularly dark at the surface hints at the presence of organic matter. A soil that has streaks of blue and grey often indicates a lack of oxygen, perhaps caused by a considerable period of waterlogging. If you meet a Soil Scientist in the field, ask them to open their fieldwork bag for they are often equipped with a series of colour charts. They are usually engaged in one of the following activities. Firstly, they are planning to redecorate the lounge, and the colour charts were accidentally brought out on fieldwork. Secondly (and more likely), these are the Munsell Soil Colour charts, with each possible soil colour linked to a universally-adopted code.


***

Soon, I shall be entering the next phase of my PhD. Having spent the majority of the last 6 months engaged in experimental planning, I will shortly begin one of the most exciting chapters: data collection and my fieldwork campaign. Having established the suitability of my sites, now it's time to intricately hatch a plan of action; a fieldwork schedule!

Later this month, after an Easter break, I look forward to attending the Early Career Researchers conference, here at Lancaster University and the European Geosciences Union General Assembly in Vienna.


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