Soil samples taken from allotment gardens in the UK were much healthier when compared to soil samples from heavily farmed fields in the region. Researchers say the findings suggest that community and urban gardens could offer a sustainable way to meet growing food demand.
“We found remarkable differences in soil quality between allotments and arable fields,” says Jill Edmondson of the animal and plant sciences department at University of Sheffield. “Our study shows how effectively own-growers manage soils, and it demonstrates how much modern agricultural practices damage soils.”
The scientists took the soil samples from 27 plots on 15 allotment sites in the city of Leicester. Samples were also taken from local parks, gardens, and surrounding agricultural land.
They measured a range of soil properties, including organic carbon levels, total nitrogen, and the ratio between carbon and nitrogen (which are all directly related to the amount and quality of organic matter in the soil) as well as soil bulk density, an indicator of soil compaction.
Compared with local arable fields, the allotment soil was found to be significantly healthier. Allotment soil had 32 percent more organic carbon, 36 percent higher carbon to nitrogen ratios, 25 percent higher nitrogen, and was significantly less compacted.
Allotment holders are able to produce good food yields without sacrificing soil quality because they use sustainable management techniques. For example, 95 percent of allotment holders compost their allotment waste, so they recycle nutrients and add carbon back to their soil more effectively.
As well as being good news for urban soils, the results underline the value of allotments, Edmondson says.
“An estimated 800 million city dwellers across the world participate in urban food production, which makes a vital contribution to food security. Our results suggest that in order to protect our soils, planning and policy making should promote urban own-growing rather than further intensification of conventional agriculture as a more sustainable way of meeting increasing food demand.”
There are around 330,000 allotment garden plots in the UK, covering more than 8,000 hectares (19 acres) and demand is growing. In the UK alone, more than 90,000 people are currently on allotment waiting lists.
Dig for Victory
The heyday for allotments was during World War II when 10 percent of the UK’s food came from less than 1 percent of its cultivated land thanks to the expansion of own-growing under the Dig for Victory campaign. At that time, one in three households in Leicester had an allotment. Following a national decline in demand, today Leicester’s allotment plots number only 3,200 and cover just 2 percent of urban green space although the city is the second highest provider of allotments nationwide.
As well as protecting soils and boosting food security, own-growing offers other health benefits, Edmondson says. “Using urban land, including domestic gardens, allotments, and community gardens for own-growing is an important and often overlooked way of increasing productivity whilst also reconnecting urban dwellers with food production.
“As well as improving food security, studies show that own-growing has direct physical and mental health benefits, and can provide access to sustainably produced fruit and vegetable crops without the associated food miles.”
Source: University of Sheffield