But what we eat too often falls short of its nutritional potential. And the effects can be insidiously progressive, in both the developed and developing worlds. Understanding the interactions that link soil, food and human nutrition to counter the threat has now become a major inter-disciplinary pre-occupation of soil and crop scientists. It’s a challenging task.
Early evidence in the UK, published in 2001, pointed to low levels of selenium in the soil as the primary cause of falling levels of the micronutrient in food. In 2008, work on the long-term wheat archive at Rothamsted Research implicated plant breeding and physiology (notably, the introduction of shorter, high-yielding varieties of wheat) in falling levels of other minerals in grains; levels in the soil have been stable or increasing since the institute’s founding in 1843.
Subsequent research has shown that enhanced fertilisers could “biofortify” crops with selenium, whose natural levels in wheat are well below those needed to help maintain daily intake recommendations through foodstuffs, such as bread. Demand for artificial additives could surface and grow if climate change further reduces levels of selenium in the soil, as research published in 2017 predicts.
But there is little “economic pull” for such initiatives with low-value commodities like bread, potatoes and milk; and there is little political push these days if the public are not demanding change or, indeed, if they are wary of change. When Finland discovered, in the 1980s, that levels of selenium in the population were too low, the government passed legislation to increase the mineral’s concentration in fertiliser. The initiative worked but Finnish authorities admit that public scepticism about additives would likely prevent them from doing the same today.
While populations in the West, or many of them, can get away with the natural nutritional deficits in their food, by altering their diet or by taking health supplements, the luxury of such choices is not readily available elsewhere. The problem is particularly acute in Africa, and is made worse by the lack of geographically-referenced baseline data to inform policy that can evolve agronomic solutions.
The Africa Soil Information Service (AfSIS) has been addressing this issue as part of the moves to bring greater choices to the continent. It is a diverse international collective that brings together soil scientists, agronomists, geographers, ecologists and data analysts from all over the world to provide such information and to map the continent’s agricultural potential. AfSIS was founded in 2009 with funds from the Bill and Melinda Gates Foundation and run from Columbia University in New York; its headquarters moved to Rothamsted Research in November 2016.
The idea is to bring independent prosperity to the nations and communities across Africa by describing and understanding their soil and landscapes so that the areas could be used to raise agricultural productivity and increase the nutritional value of crops with minimal ecological damage. To start, AfSIS is targeting its resources on the most amenable zones, those it describes as “photosynthetically active”. Though this territory represents less than 40% of the continent’s land area, or around 800M hectares, it supports more than 90% of the rural population in Africa’s 54 countries.
Finding ways of lifting nutrient levels in food, in the UK and abroad, is demanding, and the work now forms part of the institute’s 5-year strategic programme to 2022, Soil-to-Nutrition.