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October 10th, 2018 / The Conversation

Large fields, predictable rainfall and favourable temperatures have meant that farmers in Arsi Negele, a town in southeastern Ethiopia, have benefited from good crop yields. Their production of wheat and maize, two of the main food staples in Ethiopia, have also increased over time.

But there are worrying indicators that the increased yield and calories haven’t translated into sufficient vitamins and minerals. This deficiency is known as “hidden hunger” and Ethiopia is classed as having “severe” levels.

Less than 20% of children in the area have a diet that’s diverse enough to meet their nutritional needs. This is much lower than the 40-70% typically found in other developing countries, like Tanzania. Protein and zinc deficiencies are of particular concern and contribute to a variety of health issues like stunted growth in early years and poor immunity.

One of the causes of this is that, because there’s a need to feed more people, global trends prioritise high yielding cereal species and varieties as the paper refers mainly to different species over lower-yielding – but more nutritious – crops and animal products.

While it’s known that soils can contribute to nutrients in crops, the studies are very few and mostly look at horticultural crops – like vegetables, fruits and flowers. Little has been done to quantify the links between soil organic matter – plant and animal residue – and crop nutrient content, particularly in cereals.

Our study is one of the first to reveal the link between soil organic matter and crop nutrient content for a staple crop in a developing country. We found that wheat grown around Arsi Negele had more nutrients, like zinc and protein, when grown on soils rich in organic matter.

Increasing organic matter by 1% was associated with an increase in zinc equivalent to meet the daily needs of 0.2 additional people per hectare and an increase in protein equivalent to meeting the daily needs of 0.1 additional people per hectare. These modest increases in soil organic matter contribute a small, but important, increase in nutrients found in wheat. Read more