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Micronutrient transmission from soils to humans

say “we are what we eat” but can it be that we are what the soil is? Soil forms
the foundation of the food we eat. It also serves as the main reservoir of the
water we drink, making it the sole source of nutrients taken-in by humans. Naturally,
one could argue that the fate of our soils shape the state of our being and
define who we are and who we will become.
In other words, the health of us humans depends on the health of our

history, soils were the causes of the rise and the fall of ancient civilizations.
The book Dirt: The Erosion of Civilizations by David R. Montgomery highlights
a series of these events globally and calls for a paradigm shift away from the
disconnection of soil to the prosperity of a nation and its human capital. Unfortunately,
this issue is still seen in modern times and threatens our very own existence.
A recent example of this is the Dust Bowl, which was witnessed in the
American prairies in the 1930s and was marked by unimaginably catastrophic dust
storms, the leading anthropogenic cause of which was poor farming practices
that exacerbated wind erosion. This incident not only damaged the local
economy, ecology and agriculture but also had devastating consequences on the human-capital
dimension as it caused widespread hunger, poverty and disease which culminated with
a mass exodus. All this because the topsoil – the most fertile portion of the
soil’s profile – was lost.


A dust storm approaching Rolla, Kansas, in
1935. (Photo credit: Library of Congress)

When a soil is stripped of its topsoil (the layer that harbors the
key nutrients for life), the nutrients available for plants are diminished,
thus undermining plant growth and nutritional outcomes. When humans and
livestock monotonously consume from fields that are nutrient depleted, they often
exhibit the same nutrient deficiencies as their soils. While nutritionists
together with plant breeders and food scientists have made tremendous progress
in creating solutions that remediate the problem of nutrient availability
through processes such as biofortification and post-harvest interventions,
couldn’t we improve human nutrition by improving the health of our soils? Since
we humans seek nutrition ultimately from the soil, couldn’t the solution be
lying right beneath out feet? This is where my research plays in.

Dr. Ross Welch and Dr. William Allaway –two USDA-ARS scientists
and Cornell University affiliates – were among the first to investigate the
soil-to-human mineral transmission. In the mid1970s, they proved strong mineral
interlinkages in the soil-human chain. Unfortunately, not much progress has
been made in this field in recent decades, and despite the tremendous potential,
soil-to-human nutrient transmission has almost never been studied at a
household level.

In March and June 2018, with the support of the
Tata-Cornell Institute, I traveled to Jharkhand, India to perform a household
level study on the mineral transmission from soil to humans through the rice
crop intermediary. My study objective was to assess the existence and the
nature of the soil-rice and rice-human micronutrient linkages and identify key
factors in soil health that influence micronutrient transmission from soils to
humans. Households were surveyed about their dietary, health, farming and
cooking practices, and sets of soil, rice, and hair samples were collected from
fields and their corresponding female owners within each household that farm and eat from that land. Samples were sent
to Cornell University for soil health, rice nutrient and hair nutrient


Local villagers in Ranchi district, Jharkhand during my March visit. (Photo provided by author)

Why Jharkhand?

is considered one of the most vulnerable and highest health burden states in
India with a devastating health crisis: Severe malnutrition accounts for 45% of
child mortality every year in Jharkhand in addition to underweight being the most
prevalent in all India, accounting for 45.7% of children below the age of 5,
according to the Indian
Ministry of Home Affairs
. Many districts in Jharkhand also suffer from the highest
prevalence of anemia (>85%) especially among women and children. Many areas
in Jharkhand, specifically in our sampling locations, are resource poor,
infrastructurally isolated areas of subsistence farming. They are rain-fed
systems that rely heavily on single-season rice crop with no potential for
fertilization via irrigated water.

Why rice?

Rice is the highest consumed staple in India[1]. The Indian rice harvesting
area is the world’s largest, highlighting its importance in the Indian diet[2]. Rice in rural India is
consumed at the rate of a quarter of a kilo per day and represents 22% of total
expenditure on food and beverage items. It also accounts for 40% of the daily
calorie share[3]
and 32% of daily protein contribution[4].

Why hair?

Hair analysis has several advantages over the analysis of blood or
urine. Its non-invasiveness and ability to reveal retrospective information
about a human’s nutritional status over an extended period of time, added to
its ease of storage and analysis makes it an excellent long-term bio-indicator
of human nutritional status. Hair is a stable and
robust indicator that reflects the composition
of trace elements in blood plasma at the time of hair development. Hair nutrient composition was found to be correlated with
not only human nutritional status but also with human diseases, metabolic
disorders, and even environmental exposure.


against women in their own homes and intra-household food consumption disparity
often leads women to eat the leftovers of their husbands and children. They end
up eating less in quantity and quality. This is reflected on women’s
nutritional well-being where 35% of the rural women of Jharkhand have below-normal
Body Mass Index (BMI) and 67% are
anemic, according to the 2015-2016 National
Family Health Survey

I get ready to start statistical analyses on these laboratory measurements, I
am eager to discover the nature of this soil-human health relationship in
Jharkhand. As fruits of this labor, our research will hopefully be able to
provide an additional solution to nutrient deficiency that looks at the root
cause, and ultimately will identify
potential best soil management practices for better human nutrition.

By Fatma Rekik

Fatma Rekik is a PhD student in Soil Science at the College of Agriculture and Life Sciences at Cornell University. Her research focuses on soil health and its effects on the socioeconomic, nutritional and qualitative (e.g., quality and
tastiness of produce) dimensions of food and agriculture in developing nations.
This project was funded and supported by the Tata-Cornell Institute.


[1] Nguyen, V. N. (2002). Rice production, consumption and nutrition. In FAO Rice Information. Rome: FAO.

[2] Khatkar, B. S., Chaudhary, N., & Dangi, P. (2016). Production and Consumption of Grains: India. In Encyclopedia of Food Grains (pp. 367–373).

[3] Chatterjee, S., Rae, A., & Ray, R. (2007). Food Consumption and Calorie Intake in Contemporary India. ESS Working Paper Series, (April 2007), 1–14. Retrieved from

[4] Bienvenido, J. O. (1993). Rice consumption and nutrition problems in rice consuming countries. In Rice in human nutrition. Rome: FAO.