Study one – Get on your bike !
The first study is by an MSc student at Surrey, who examined the greenhouse gas (GHG) emissions that result from the production of fruit and vegetables on an allotment in Warwickshire. The study looked at the costs of growing produce in terms of the ‘carbon’ that is all the carbon we burn when travelling to the allotment in petrol or diesel, plus the costs of making and transporting any fertilisers and pesticides we use, and can also include the bags we use to carry produce away. Even if you don’t use fertilisers because you are organic, then remember if you use animal manures, then you might include an element of the cost of raising the animals in the first place, and then transporting the muck to your allotment and so on…. Details of the study are as follows:
The contribution to climate change (“global warming potential” i.e. GWP) of all inputs and processes to growing fruit and vegetables on a Warwickshire allotment was estimated to be 0.93 kg carbon dioxide and equivalent emissions (CO2e) per kg harvested product per annum. When considering the total produce (assume this also includes things like eggs and honey) the figure was lower at 0.70 kg CO2e per kg per annum. The largest contribution to this figure was fuel use (42%), and the next two largest items were fertilisers and pesticides (27%) and capital equipment & machinery (23%). The remaining items; waste, mains water, crop protection and seeds contributed collectively the remaining 8%.
Comparing this result with commercial production the GWP of produce grown on the allotment was generally worse than outdoor (=field) grown but considerably better than protected indoor (= glasshouse) commercial production. The figures for commercial production were obtained from published literature and ranged from 0.2-1 kg CO2e per kg product for outdoor grown produce and 1.1-4.6 kg CO2e per kg product for indoor grown produce.
Improvements that could be made are clearly in the area of fuel use. To you and me, that means driving to and from the allotments. In the Warwickshire study, the majority of the plot holders lived within a couple of km of the site but still drove to and from the site; alternative modes of travel, such as cycling, would reduce emissions. The application of fertilisers and pesticides could also be looked at in more detail to see what savings could be made. There is however a positively correlated relationship between application of fertiliser and yield and therefore simply cutting back on fertiliser could result in lower yield and hence very little change in overall GWP measured as per kg produce (pa).
Study 2 – Something for the Silver Surfers
The second study was a Dutch study and it found that elderly allotment gardeners tend to be healthier and experience greater wellbeing than their less active counterparts – although not in the case of younger people.
Background
The potential contribution of allotment gardens to a healthy and active life-style is increasingly recognized, especially for elderly populations. However, few studies have empirically examined beneficial effects of allotment gardening. In the present study the health, well-being and physical activity of older and younger allotment gardeners was compared to that of controls without an allotment.
A survey was conducted among 121 members of 12 allotment sites in the Netherlands and a control group of 63 respondents without an allotment garden living next to the home addresses of allotment gardeners. The survey included five self-reported health measures (perceived general health, acute health complaints, physical constraints, chronic illnesses, and consultations with GP), four self-reported well-being measures (stress, life satisfaction, loneliness, and social contacts with friends) and one measure assessing self-reported levels of physical activity in summer. Respondents were divided into a younger and older group at the median of 62 years, which equals the average retirement age in the Netherlands
After adjusting for income, education level, gender, stressful life events, physical activity in winter, and access to a garden at home as covariates, both younger and older allotment gardeners reported higher levels of physical activity during the summer than neighbours in corresponding age categories. The impacts of allotment gardening on health and well-being were moderated by age. Allotment gardeners of 62 years and older scored significantly or marginally better on all measures of health and well-being than neighbours in the same age category. Health and well-being of younger allotment gardeners did not differ from younger neighbours. The greater health and well-being benefits of allotment gardening for older gardeners may be related to the finding that older allotment gardeners were more oriented towards gardening and being active, and less towards passive relaxation (in other words sitting at home watching ‘Loose women’ on the telly).
Conclusions
These findings are consistent with the notion that having an allotment garden may promote an active life-style and contribute to healthy aging. However, the findings may be limited by self selection and additional research is needed to confirm and extend the current findings. To download the study click here.
Full references and further reading
Carter C. (2010). Global Warming Potential of produce grown on an allotment using a life cycle assessment approach Case Study: Wellesbourne Allotment, MSc Thesis, University of Surrey, 2010.
Van den Berg A E, Van Winsum-Westra, De Vries S and Van Dillen S M E (2010). Allotment gardening and health: a comparative study among allotment gardeners and their neighbours without an allotment. Environmental Health 2010, 9:74 doi:10.1186/1476-069X-9-74
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