Page 27 - ALG Issue 3 2014

Allotment growing maintains top quality soil conditions
A recent report by researchers at Sheffield, Kent and Exeter Universities1 has found that cultivation practice on allotments has a positive effect on the main indicators of soil quality. These include: Soil organic carbon levels (SOC), total nitrogen (TN), and the ratio between carbon and nitrogen (C:N). These are all directly related to the amount and quality of organic matter in the soil, as well as soil bulk density
(BD), an indicator of soil compaction.
The team compared allotment, urban green- space, domestic garden and agricultural soils from sample sites in and around Leicester and found that allotment soils had 32% higher SOC concentrations and 36% higher C:N ratios than pastures and arable fields. They also found 25% higher TN and 10% lower BD than arable soils.
favourable management practice as bonfires are detrimental to air quality.
As a great deal of the inputs in to allotment soils are derived from agricultural products e.g. chicken manure along with commercial composts, fruit and vegetable waste and also synthetic fertilisers produced from petro-chemicals, the writers
Researcher Jill Edmondson states that “This remarkable contrast in soil quality indicators
between allotments and arable fields reveals the effectiveness of management achieved by own-growers”.
The plot holders answered a questionnaire that examined their plot management practices; this included composting, inputs
of manure, fertiliser/commercial compost and the burning or removal of organic matter. Three-quarters of the allotment plot holders added manure, 95% composted biomass on-site, and many added organic-based fertilisers and commercial composts. The researchers felt that this may explain the maintenance of SOC, C:N ratios, TN and low BD, which are positively associated with soil functioning. Although some gardeners did apply ash and char from bonfires on to the soil, further improving the soil with the highly stable organic carbon, this was viewed as a less
urban agriculture globally, and its important contribution to food security, our findings suggest that to better protect soil functions, local, national and international urban planning and policy-making should promote more urban own-growing in preference to further intensification of conventional agriculture to meet increasing food demand.”
The full report can be downloaded from http://onlinelibrary. wiley.com/doi/10.1111/1365-2664.12254/pdf.
1Jill L. Edmondson1*, Zoe G. Davies2, Kevin J. Gaston3 and Jonathan R. Leake1 1Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
The team compared allotment, urban green- space, domestic garden and agricultural soils
felt that to be truly sustainable other sources needed to be found for these nutrients. They suggest that use of the compost produced from putrescible waste by local councils was a way of reducing this dependence. In their summary of findings the research team state that:
“Our study establishes, for the first time, that small-scale urban food production can occur without the penalty of soil degradation seen in conventional agriculture, and maintains the high soil quality seen in urban green-spaces. Given the involvement of over 800 million people in
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