Goodbye ATX

I write my final blog post sat in my favourite coffee shop on South Congress. As I sit and sip on my drink, I am able to reflect on these past eight months - or so I thought I would be able to do. I had not anticipated how hard it would be to answer the supposedly easy question ‘how was your year abroad?’ This has become especially apparent as I continue to deliberate what to write; it is clear just how difficult it is to choose what to say whilst still ensuring I am forming coherent sentences. Unsurprisingly, my page has become a series of disjointed and half-written sentences interlinked with confused arrows. Perhaps this reflects the extent of what I truly want to say; how I want my time here to be reflected well in order to give it the justice it deserves. So here it goes…

Whether people have been to the US or not, everyone has an opinion of the country, the Land of the Free and the Home of the Brave, the greatest country in the world. People say good things but people also say bad things. Expectantly, I arrived in August, completely unaware what this year would bring. I didn’t get the significance of them dumping the tea into the harbour and I didn’t even know Texas had been its own country in the past. But now that’s changed, and through my time here, I’ve been able to generate my own set of opinions on the USA. I’ve been shown a side of the USA that I like: the friendliness, openness, and approachability of the people I’ve met; Austin’s eccentricity, its small town feel in one of the fastest growing cities in the country, and its countless cacti; the never-ending blue skies and 32-degree heat, even in April; and the new topics I have wouldn’t have been able to learn at UCL, whilst simultaneously having the opportunity to have the infamous American university experience.

It has been an interesting year to the be in the US. The word ‘interesting’ is truly an understatement and does not quite fit the description; perhaps a more suitable word would be ‘insane.' The change in administration shocked the world. I’ve been fortunate to witness this first-hand, seeing those exasperated discussions and conversations, and hearing the fitting analogy of the election to a Black Mirror episode… Being in the country, I’ve observed the uplifting resistance and opposition. Interning with the Sierra Club Lone Star Chapter here in Austin, I have seen Texas’ considerable green side and relentless battle against President Trump; I’ve been able to meet a collection of inspiring individuals who care so much about changing the state for the better. That’s something I’ll remember.

So, going back to the question on how my year abroad has been… I will say it has been an experience that I am profusely thankful for; I’ve been part of a culture so different to the one I’m used to at home, met people whom I never thought I would ever have had the chance to, seen places I never thought I would see, and have learnt many things (good and bad) along the way. And as I conclude this post, it marks the beginning of the end of my time here at UT; there are only ten days until the end of the semester and four short weeks until I leave Texas. Unsurprising, the mad rush of completing my Austin bucket list begins now. You’ve been nice, Austin. I’ll make sure to say some good things about you when I return home and hopefully I’ll see you some point in the future.

Terra preta as a super soil

Amazonian ecosystems exhibit low fertility levels in highly weathered soils and therefore, it has been assumed for many years that environmental limitations prevent intensive agriculture in this region (e.g. Meggers, 1954). Within this ecosystem, however, patches of dark-coloured soils have been found; these patches exhibit stark differences in soil properties compared to the predominant soils in Amazonia, with the dark patches being characterised by high organic matter and nutrient levels (Glaser, 2007). These dark soils are locally called Terra Preta de Indio, which translates to Amazonian Dark Earths.

Terra preta is typically defined as a soil characterised by a several decimetre-thick topsoil horizon, which exhibits high levels of soil organic matter, biochar, and nutrients in addition to containing archaeological artefacts of pre-Colombian origin (Glaser and Birk, 2012). A typical terra preta soil profile exhibits a number of varying qualities that differ to a ferralsol, the region’s predominant soil. Ferralsols tend to have a shallow surface horizon that is light brown in colour. This horizon overlays a several metre thick subsoil horizon that has a loamy or sandy texture with a structure dominated by micro aggregates (Glaser et al. 2001). Terra preta on the other hand, has a dark grey or black coloured topsoil that can reach a depth of up to one metre. Within this horizon, potsherds, small bone, and charcoal particles are commonly found in addition to signs of bioturbation and aggregates of biogenic material. Beneath this horizon, there is a light coloured layer that tends to show patches of different brown, grey, and black colour. This layer shows clear signs of mixing of topsoil and subsoil material. Significantly, the subsoil horizons are identical to the subsoil horizons found in the adjacent soils in the area (Glaser et al. 2001).

Terra preta soils have historically presented a conundrum regarding their formation; previous theories have included allochthonous inputs, including volcanic deposits from the Andes or from sediment deposits from ancient lakes (Glaser and Birk, 2012). However, pedological and archaeological investigations have confirmed that this soil has an anthropogenic origin, formed from waste and charcoal deposits made by pre-Colombian Indians from 500 to 2500 years B.P. and abandoned after the invasion of Europeans (Neves et al. 2003).

It is these charcoal deposits that have made terra preta soils so unique; the porosity of the bio-char facilities the formation of organic chemical compounds, resulting in the soil to become rich in carbon, as well as other essential nutrients, such as NPK, which in turn increases the fertility of the soil (Glaser and Knorr, 2008). Similarly, increased fertility is also facilitated by the high organic matter content; it increases nutrient recycling and results in the soil to have a high cation exchange capacity, which limits leaching (Glaser, 2007). Furthermore, the presence of pottery shards acts as a mulch layer, limiting soil moisture loss while the uniquely evolved microbes present in the soil contribute to soil richness and nutrient recycling (Woods and McCann, 1999).

Unsurprisingly, terra preta could act as a model for sustainable agriculture in the humid tropics and other soils characterised by a low nutrient holding capacity. The techniques that led to the formation of terra preta have the capability to decrease land degradation from recently utilised intensive agriculture in the region in addition to reclaim the degraded areas (Glaser, 2007). Furthermore, the high stability of soil organic matter in terra preta coupled with experimental data (e.g. Kuzyakov et al. 2009) has shown that carbon can be sequestered for millennia within this type of soils. Consequently, terra preta has the ability to combine sustainable farming practices with long-term carbon dioxide sequestration. It would not be wrong to speculate the potential this black soil has in transforming agriculture around the world. 

References 

Denevan, W.M. (1996) ‘A bluff model of riverine settlement in prehistoric Amazonia’, Annals of the Association of American Geographers, 86, 654-681. 

Glaser, B. (2007) ‘Prehistorically modified soils of Central Amazonia: a model for sustainable agriculture in the 21st century?’, Philosophical Transactions of the Royal Society B: Biological Sciences, 362, 187–196, 

Glaser, B. and J.J. Birk (2012) ‘State of the scientific knowledge on properties and genesis of Anthropogenic Dark Earths in Central Amazonia (terra preta de Índio)’, Geochimica et Cosmochimica Acta, 82, 39-51. 

Kern, D.C., G. D’Aquino, T.E. Rodriques, F.J.L Franzao, W. Sombroek, T.P. Myers and E.G. Neves (2003) ‘Distribution of Amazonian Dark Earths (terra preta) in the Brazilian Amazon’ in J.Lehmann et al. (eds.) Amazonian Dark Earths: Origin, Properties, Management. Kluwer Academic Publishers: Dodrecht, 105-124. 

Kuzyakov. Y, I. Subbotina, I. Bogomolova, and L. Xu X. (2009) 'Black carbon decomposition and incorporation into soil microbial biomass estimated by 14C labeling', Soil Biology and Biochemistry, 41, 210-219. 

McCann, J.M., W.I. Woods and D.W. Meyer (2001) ‘Organic matter and Anthrosols in Amazonia: interpreting the amerindian legacy’. In: Sustainable Management of Soil Organic Matter (eds. Rees et al.), CABI Publishing: Wallingford, 181-189.

Meggers, B.J. (1954) ‘Environmental limitation on the development of culture’, American Anthropologist, 56, 801-824. 

Neves, E.G., J.B. Peterson, R.N. Bartone and C.A. Da Silva (2003) ‘Historical and socio-cultural origins of Amazonian Dark Earths’ in J. Lehman et al. (eds.) Amazonian Dark Earths: Origin, Properties, Management. Kluwer Academic Publishers, Dodrect, 29-50. 

Sombroek, W. D. Kern, T. Rodriguez, M. Cravo, W. Woods and B. Glaser (2002) ‘Terra preta and Terra mulata: pre-Columbian Amazon kitchen middens and agricultural fields, their sustainability and their replication’. In: 17th World Congress of Soil Science.

The Daily Texan

The Daily Texan is a student led newspaper distributed daily at UT. You only have to walk twenty metres to find your free copy on campus. Last semester, I would read it every day, but this semester I have been a little lax. Regardless, I like reading them: the reporting on current Texan matters, their short yet effective opinion pieces, the insights into events on campus, and the informative coverage of UT sports.

It’s made me wish that UCL had its own daily newspaper. I would definitely read it.

Find out more about the Daily Texan by visiting http://www.dailytexanonline.com/

Providence Canyon: a testament to human influence on nature

Providence Canyon state park, with its 16 gullies reaching down to 150 feet and its soft soil shaded in orange, red, pink, and even purple tones, proved to be an interesting topic of discussion in class. The state park is located in south-west Georgia and is commonly referred to as Georgia’s Little Grand Canyon. The network of gorges, cliffs, plateaus, and pinnacles has attracted not only tourists but a host of academic attention.

Providence Canyon is regarded to be so spectacular because of its remarkable proof of anthropogenic devastation on nature. The canyons were once believed to be a natural phenomenon and in the 1930s, were even described as a gift from God (Sutter, 2010). Over time, however, Providence Canyon would be used to show the devastating effects human induced land-use change was having on the environment.

The park is located in Stewart Country, an area renowned for its history of human induced soil erosion (Sanders, 2015); grassland prairies were rapidly converted to cotton fields by settlers, where the region was eventually transformed into one of the richest areas of the plantation South (Terrill, 1958). However, agriculture was extensive and the soils became exhausted; south-eastern soils tend to be ultisols, commonly acidic and mineral deficient that are prone to exhaustion if not properly managed (Richter and Markewitz, 2001). Therefore, unsurprisingly, sustained cropping in tobacco, cotton, and corn depleted the soils and the canyons began forming in the early 1800s due to poor soil-management practices (Sanders, 2015).

Vegetation that once held soil in its place was removed, leaving exposed soil that was susceptible to the erosive effects of rainfall characteristic of the region. Furthermore, the top layer of soil was easily washed away, which left the less permeable clay horizon exposed; the soil became susceptible to destabilisation from below, producing caving, sloughing, and piping, while the exposed clay layer also decreased the infiltration rate, increasing surface flow and erosion (Sutter, 2010). Additionally, the erosivity of runoff was magnified by farmers ploughing up and down slopes that resulted in water to concentrate in furrows while simultaneously decreasing the infiltration capacity of the soil surface. Consequently, hillside ditches and poorly built and maintained terraces became gullies (Sutter, 2010).

To exacerbate the issue, rainfall in the southeast tends to concentrate in the Spring and early Summer when the cropped fields traditionally lacked vegetation cover to help protect against the erosivity of the rainfall (Sutter, 2010). Southern farmers did not have the resources, technology, and the networks to help decrease the major erosion problems. Similarly, the farmers lacked the motivation to deal with the issue; as long as there was land available, the farming practices continued and by 1860, Stewart County was producing 19,165 bales of cotton, ranking second amongst all the counties in Georgia (Sutter, 2010). Cotton production in the county peaked around 1890 but by the 1930s, the gullies were at the depth of their development (Magilligan and Stamp, 1997). The irony of apparently fine working lands and deep gullies had become especially apparent.

Providence Canyon demonstrates the power of human agency and our species’ ability to transform the landscape. Once Providence Canyon became a state park in 1971 (Sutter, 2010), it could be argued that it began to represent where we went wrong and consequently, now highlights our shortcomings, which in turn prevent us from inflicting such environmental damage again. On the other hand, we arguably started to celebrate the beauty of an environmental disaster. It is not hard to be amazed by the canyon’s beauty; if you were oblivious to its formation, it would be easy to be impressed at nature’s ability to carve out such intricate features. However, once I found out that Providence Canyon was a result of unsustainable farming practices, I was disappointed. In my opinion, the canyon signifies what happens when ideas and modes of production are implemented into complicated new environments without regard, restraints, or enthusiasm to pay attention and adapt accordingly. Nonetheless, I would love to be able to see Providence Canyon for myself.

References
Magilliga, F. and M.L. Stamp (1997) ‘Historical Land-Cover Changes and Hydrogeomorphic Adjustment in a Small Georgia Watershed,’ Annuals of the Association of American Geographers, 87, 614-635.

Richter, D.D. and D. Markewitz (2001) Understanding Soil Change: Soil Sustainability over Millennia, Centuries, and Decades, Cambridge: Cambridge University Press.

Sanders, S. (2015) Providence Canyon [Online]. Atlanta: New Georgia Encyclopedia. Available at: http://www.georgiaencyclopedia.org/articles/geography-environment/providence-canyon [Accessed 5th April 2017].

Sutter, P. (2010) ‘What Gullies Mean: Georgia’s Little Grand Canyon’, Journal of Southern History, 76, 579-616.