Harvesting Zinc for Healthy Soils, Crops and People

Micronutrient deficiency, or hidden hunger, is a lack of vitamins and minerals in the diet and is a devastating form of malnutrition.  Two billion people are afflicted, including half of the world’s children under the age of five.1

Zinc deficiency is a particularly debilitating condition that causes premature birth, cognitive and physical underdevelopment and immune system suppression. Seventeen percent of the global population does not get enough zinc in their diets and nearly half-a-million people die from zinc deficiency every year.2

Zinc deficiency rates are highest in the rural areas of developing countries where millions of small-scale farmers grow and consume cereal grains (maize, wheat or rice) that have inherently very low levels of zinc.3  Improving the zinc concentrations in these crops can dramatically reduce zinc deficiencies for this vulnerable population.

The Mosaic Company is one of the private-sector, foundation and university supporters of the HarvestZinc project which has identified methods for biofortifying cereal crops with zinc through fertilization. The project was led by HarvestPlus, a CGIAR institution that develops biofortified food crop technologies to improve nutrition and agricultural productivity.

Biofortification is typically done with a breeding technique that produces plants with a higher micronutrient content. Millions of small-scale farmers use biofortified seeds and benefit from the higher nutrient levels.

Zinc fertilization is an agronomic biofortification strategy where biofortification of the crop happens within the plant during the growth and development process.

Field trials over nine years in 12 countries demonstrated that spraying a fertilizer containing zinc on plants toward the end of the growing process doubles the zinc concentration in the harvested grain.4 This technique is called foliar fertilization.

Depending on the soil’s zinc status, application of zinc-containing fertilizers to the soil may also contribute to improved grain zinc levels.

Photo credit: Dr. Ismail Cakmak

Field trials revealed that fertilizing the soils with a combination of zinc and nitrogen, in addition to foliar fertilization, further enhanced the zinc levels in the plants and the grain. These results indicate that soil fertilization strengthens the root growth and root uptake system which improves the plant’s ability to retain zinc and supports increases in yields.

Of the crops tested, wheat and rice had the strongest improvements in zinc concentration following zinc fertilization.

Agronomic biofortification is a promising and cost-effective strategy for combating malnutrition in the era of climate change. Increased atmospheric CO2 may cause a decline in the nutrient concentration of crops, including zinc.[5]

Properly applied zinc fertilizer is a rapid, effective solution to reducing zinc deficiency, especially for small-scale farmers who grow most of their food.

Combining plant breeding technologies with agronomic biofortification techniques would amplify the benefits of both approaches and holds significant promise for reducing zinc deficiency in human nutrition while improving crop yield and resilience.

 


 

  1. Micronutrient Facts online, Centers for Disease Control and Prevention, accessed August 21, 2018, https://www.cdc.gov/immpact/micronutrients/index.html.
  2. Micronutrient Facts online, Centers for Disease Control and Prevention, accessed August 21, 2018, https://www.cdc.gov/immpact/micronutrients/index.html.
  3. Cakmak, I., “HarvestPlus Zinc Fertilizer Project: HarvestZinc,” Better Crops, Vol. 96, No. 2, 2012.
  4. Cakmak, I., “HarvestPlus Zinc Fertilizer Project: HarvestZinc,” Better Crops, Vol. 96, No. 2, 2012.
  5. Myers, S.S. et. al., “Increasing CO2 threatens human nutrition,” Nature, 510(7503), 139-142, 2014.

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