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Forming better soils, gardens and farms

By Dave Armstrong - 30 Apr 2014 10:0:0 GMT
Forming better soils, gardens and farms

A good brown earth, but the farmer has problems maintaining any semblance of original forest soil using current farming techniques. The labour intensive allotment gardener does approach the natural soil condition found under woody vegetation, so how can we achieve water holding, nutrient-rich, carbon retaining soil conditions? Brown earth image; Credit: © Shutterstock

To get the most out of farms, thee soil has to lose most of it's useful organic matter. Inorganic ions are replaced by fertilizer that doesn't operate correctly in the natural soil chemistry. The soil ecosystem in other words and the human infrastructure built on agriculture are a poor fit with unknown effects on each other.

Jill Edmondson and 3 three colleagues from the Universities of Sheffield, Kent and Exeter (UK) have published an extensive paper on the problems in The Journal of Applied Ecology:- Urban cultivation in allotments maintains soil qualities adversely affected by conventional agriculture.

They compare total nitrogen, C:N ratios, soil organic carbon (SOC) and bulk density between agricultural soils and English allotments. And find that the personal approach of allotment holders maintains soil integrity, while modern farming techniques have ruined soil structure and normal soil chemistry environments. Neither pasture nor arable land could compete with the enhanced natural composition of the soil generally found, and of course produced in people's allotment gardens.

Nutrient cycling is perhaps only the most obvious benefit afforded these "personally-produced" soils gardeners compost all their vegetable waste in these allotments, used extensively during WW2 and, again, in recent local council moves to release land for people to grow their own produce. Soil organic carbon is also but up as "capital," from which plants can draw down materials, to be later replaced.

The water holding capacity as well as the resultant filtering capacity and several other soil functions are seriously affected by current agriculture. Erosion and river eutrophication are the most obvious catastrophes that are caused by soil change, but the release of carbon dioxide from many such carbon stores is increasingly being quantified at a high level. Global warming may continue without the use of fossil fuels, if these quantities are significant.

800 million people produce some kind of urban "garden produce." It's likely that in order to produce tasty and large crops, these same mini-agriculturalists take great care with composting and soil health. The difference from large scale farming has been always there, but the science of how they differ is critical. Both the US and the UK are gaining thousands of adherents in an age when the hippy background and the financial outlook no longer form major influences.

Around the sample city, Leicester (pronounced, "Lester"), there are a third of a million people in a very urbanised midland area of England. The 15 chosen allotments there would be typical of British plots and their gardeners nationwide. Some added manure (75%) but others perhaps couldn't find much! Fertilizer was used alongside commercial compost (Some cities provide a cheap composting facility.) Results, as expected were many times more successful in cropping than commercial enterprise- between 400 and 1100%).

Results indicate that woody vegetation produced higher SOC concentrations, especially in the domestic allotment, but the real comparison was with the sub-optimal levels in agricultural soils. This is a serious problem for farmers, along with soil quality generally, and I'm sure the farmer would be first to point out his awareness of garden and other soils, probably even on his or her own land. However, the research now points to its results as leading to even more awareness of solutions to soil depletion. We await reactions worldwide with interest!