Good tidings we bring to you and your king

Merry Christmas! I hope you're having a wonderful festive period, receiving lots of present and eating far too much! In keeping with the festive theme I thought it might be interesting to take a look at the farming practices and environmental impact of the Christmas Turkey Industry.

For the majority of us turkey only hits our dinner plates once a year, but the turkey industry is in fact huge, and is not limited solely to the month of December. Amazingly DEFRA's (2011) Poultry and meat statistics report states the 'carcass weight' of turkey makes up greater the 10% of total poultry production. In many European countries this value is even greater. Because demand for turkey is generally isolated to such a short period of time the market demands huge quantities of turkey be produced all at once. This means the market is generally dominated by industrial farms, owned by large corporations.

In general the environmental impacts related to turkey production are much the same to those of other poultry, including poor management of manure, litter and organic waste like bones and feathers, while also being associated with acidification, eutrophication and of course greenhouse gas emissions (Rodic et al, 2015). Gerber and others (2007) give a very detailed review of poultry related environmental impacts at local and at watershed level scales, with the problems largely boiling down to an excess of waste that cannot be managed by land disposal or recycling. Indeed poultry production's greatest issue is the associated pollution of nearby soil and water with nitrates, heavy metals, drug residues and pathogens. Willaims et al (2006) conducted an interesting study regarding the poultry sector as a whole, comparing organic (free-range) and non-organic (intensive) farming techniques. Curiously, organic poultry production is the only 'organic' animal production system to have more harmful environmental impacts than the non-organic, intensive counterpart. It would be interesting to see if this finding varies between different types of poultry which vary significantly in weight and from which we take different types of produce i.e for chickens we take both meat and eggs.

Perhaps due to the relative isolation of turkey production systems they have seen little academic interest until recently where it has become apparent that agriculture as a whole is having more significant environmental impact. Life Cycle Assessment (LCA) is an approach that has been used for a number of other farm animals and is gaining traction in the turkey industry also. An LCA involves compiling environmental data for all the activities in an entire process, from birth of the livestock to the supermarket shelf. Environmental impacts are quantified in terms of 'primary energy (PE) use, global warming potential (GWP), eutrophication potential (EP) and acidification potential (AP)'. The tool can then be used to predict the impacts of changes in management or agricultural practice. 

Source: Andrew Moore's presentation to Perth Green Drinks, 2013

I found a couple of studies which focused only on Turkey production, one of which compared the environmental impacts of UK turkey production (Leinonen et al, 2015) and one that modeled the effects of mitigation strategies (Leinonen et al, 2014)

Leinonen and others (2015) compared controlled ventilation and non-controlled ventilation systems for male and female turkeys concerning environmental impact, and is one of the first studies to do so using detailed industry data, provided by the the main UK turkey production companies, which included figures for energy consumption, amount and type of feed and bedding, and final turkey weight. The study found the main variables affecting environmental impacts were feed conversion ratio (i.e the efficiency of turkeys), housing and manure emissions and slaughter weight (which is related to energy use per turkey).

The 2014 project modeled the effects of various mitigation strategies. One of these strategies is the replacement of soybean feed with rapeseed or sunflower feeds which both have lower land use change implications and can be imported from much close therefore cutting emissions from travel. While the theory behind this technique is sound the model showed no significant difference in environmental impacts, in large part due to the lower efficiency of the new feeds, therefore the birds would not grow to the same size. Another of the strategies was to adjust stocking density i.e bird weight / land area. As expected lowering stock density had greater environmental impact, particularly in terms of global warming potential. The most successful mitigation strategy was to use manure as fuel rather than as a fertilizer. The technique poses obvious biosecurity risks however it proved particularly advantageous in the model regarding acidification and eutrophication potential.

Final thoughts...


Festive themed post today looking at a Christmas-specific agricultural industry. I was surprised to see there is work being done in such a specific area and one article I read was keen to point out that the relatively small size of the turkey industry, dominated by only a few large farms, allows it to make efficiency and environmental impact changes easily in comparison to other agricultural industries in a time where there is increasing pressure on companies to do so. Poultry is particularly damaging to soil and water, and it the specific pressures of turkey being popular only at certain times of the year provides unique problems. Research in this area highlights the specificity required when looking at mitigation strategies within agriculture, even between similar agricultures industries such as those of poultry. 

The worst drought in over a century yet agriculture continues to prosper?

Remember the California drought? While it's no longer being reported on as frequently by many news outlets, California has entered it's 6th year of drought, with the most recent U.S Drought Moniter report declaring 43% of the state is considered in extreme-to-exceptional drought. Surely a lack of rainfall this severe would have some some pretty scary implications for America's most productive agricultural region?

Source: US Drought Moniter

Apparently not.

Alongside record-breaking drought statistics, California is also achieving record-high net income figures for the agriculture sector (Grueue, 2015). This seems odd considering agriculture, especially industrial agriculture, is heavily dependent upon freshwater. How can it be possible for agriculture to thrive when there is such a lack of rainfall?

To find the answer to this we have to look underground, literally, because the reason for California's continued agricultural success is groundwater.

Withdrawing water from aquifers is, at the moment, working for California, but it is undeniably only a temporary fix. California therefore is serving as a perfect example of the wide-ranging impacts agriculture has on water and the potential environmental damage this can cause.

An OECD report on the matter describes the global expansion in use of groundwater for irrigation as a 'silent revolution' which has happened over the past 4 decades, enabled by the 'on-demand' nature of groundwater which is not affected by lake or river level variations over short timescales. The advantages of having a constant supply of clean water for irrigation means that in many countries withdrawals have exceeded natural recharge rates.

In California, groundwater abstractions have been vital in sustaining agriculture for over a decade and there is certainly a case to say that abstractions even before the onset of drought were unsustainable. The Gravity Recovery and Climate Experiment (GRACE), which was launched in 2002, takes measurements of the Earth's gravity field, from which information about natural systems can be inferred. Using this satellite data Famiglietti and others (2011) estimated a 31km³ loss in groundwater storage between 2006 and 2012. A more recent study (Howitt et al, 2014) then found a further 6.3km³ loss in only two years of drought between 2012 and 2014.

What does this mean for California?

In the short term excessive groundwater pumping can cause a number of environmental changes. One of these is sea-water intrusion. When groundwater is extracted from coastal aquifers the equilibrium between saltwater and freshwater at the aquifer-sea boundary shifts in the favour of sea water. This means that as groundwater levels decline, saltwater diffuses into the soils making them saline. Saltwater intrusion therefore spoils vital water sources both for human  and non-human use. 

Another environmental change caused by unsustainable groundwater abstractions is land subsidence. As the total volume of water held in soils drastically declines, the subsoil compacts, reducing in volume, allowing the land to be lowered, which can have devastating effects on infrastructure. This effect reduces the capacity of the aquifer to hold water in the future and is likely irreversible. Just take a look at this map which shows areas where subsidence has been attributed to groundwater abstraction. California's list goes on and on! 

Source: http://water.usgs.gov/edu/earthgwlandsubside.html

In the long term, California's overuse of groundwater could have serious implications.The problem will only get worse, groundwater quality will continue to decline, and water stress will increase. All of this in a time where the future looks to be even hotter and even drier. The end of Californian agricultural powerhouse?

State agencies such as the Department of Water Resources and State Water Resources Control Board have been tasked with overseeing new legislation that regulates groundwater abstraction in 127 of the most 'at risk' water basins. Management plans must be set up by 2022 and must ensure water use in their respective regions is fair and sustainable. But sustainable water use is likely to reduce agricultural output from the region and so the new legislation is not without significant opposition. Many farmers have already shown apprehension, where for the past century landowners have had free access to any and all of the water found beneath their land.  It's a difficult situation which triggers a number of opposing laws in the US and it is therefore expected that many major players will attempt to sue basin management agencies.

Final thoughts...

Slightly off-topic this week, although I think the story of California serves as a great example of the struggle between maintaining/increasing profit while preserving the environment and it's resources. Even in the face of sever environmental changes and water stresses, it is still incredibly difficult for legislation to be passed that can curb the activities of such profit driven industries. In fact many of the particularly commercial farms may be able to bypass new groundwater legislation using expensive legal processes. It will be interesting to see how the situation progresses in California, who are the winners and who are the losers, and ultimately at what point does the condition of the environment truly become the main priority.

Sequestering Methane?

We've all heard about carbon capture and it's potential to impede climate change. What of methane; the primary greenhouse gas produced by industrial livestock farming?

Theoretically atmospheric methane removal has no limit, unlike carbon capture which is inconceivable because CO2 vital to ecosystem success (Boucher and Folberth, 2010). This combined with the greater potency of methane (25x) makes methane sequestration technologies worth exploring.

There are a number of ways methane can be broken down and removed from the atmosphere although collectively they require high temperatures and produce unwanted waste products. As is often the case, nature has provided us an answer to this problem in the form of methanotrophs, bacteria which serve the opposite function to those found in the gut of ruminant animal, converting methane into more favourable chemicals.

Yoon and others (2009) recently conducted a study on the feasibility of atmospheric methane removal using biotrickling filters containing methanotrophs. Their model suggested the method would only be effective where methane concentration exceeds 500 ppmv. One such location that this occurs would be on a factory farm! Unfortunately the cost of this method is a major drawback. At up to 20x more expensive for equivalent carbon capture devices it is not an economically appealing system.

Source: https://emis.vito.be/en/techniekfiche/biotrickling-filter

It has been suggested that chemically mimicking these bacteria could be a more efficient and economically viable option (Ravilious, 2010). Rosenzweig and others (2010) were able to identify the make-up of the specific enzyme within methanotrophs that catalyzes the reaction which breaks down methane. It is hoped this finding could be implemented into previous biotrickling devices or future methane removal technologies.

Final thoughts...

Looking for studies that tackle the issue of methane sequestration specifically was difficult. Hypothetically methane-removal is a very appealing climate change mitigation strategy although it has become obvious to me that it is also an extremely complicated one. Small concentrations of methane in the atmosphere and it's low chemical reactivity mean sequestration is currently limited to specific environments and it is obvious in the literature that overcoming these problems remains the biggest concern.