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Humanity faces the grand challenge of feeding a growing, more affluent population in the coming decades while reducing the environmental burden of agriculture. Approaches that integrate food security and environmental goals offer promise for achieving a more sustainable global food system, yet little work has been done to link potential solutions with agricultural policies. Taking the case of cereal production in India, we use a process-based crop water model and government data on food production and nutrient content to assess the implications of various crop-shifting scenarios on consumptive water demand and nutrient production. We find that historical growth in wheat production during the rabi (non-monsoon) season has been the main driver of the country’s increased consumptive irrigation water demand and that rice is the least water-efficient cereal for the production of key nutrients, especially for iron, zinc, and fiber. By replacing rice areas in each district with the alternative cereal (maize, finger millet, pearl millet, or sorghum) with the lowest irrigation (blue) water footprint (WFP), we show that it is possible to reduce irrigation water demand by 33% and improve the production of protein (+1%), iron (+27%), and zinc (+13%) with only a modest reduction in calories. Replacing rice areas with the lowest total (rainfall + irrigation) WFP alternative cereal or the cereal with the highest nutritional yield (metric tons of protein per hectare or kilograms of iron per hectare) yielded similar benefits. By adopting a similar multidimensional framework, India and other nations can identify food security solutions that can achieve multiple sustainability goals simultaneously.
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Alternative cereals can improve water use and nutrient
supply in India
Kyle Frankel Davis
*, Davide Danilo Chiarelli
, Maria Cristina Rulli
, Ashwini Chhatre
Brian Richter
, Deepti Singh
, Ruth DeFries
Humanity faces the grand challenge of feeding a growing, more affluent population in the coming decades while
reducing the environmental burden of agriculture. Approaches that integrate food security and environmental goals
offer promise for achieving a more sustainable global food system, yet little work has been done to link potential
solutions with agricultural policies. Taking the case of cereal production in India, we use a process-based crop water
model and government data on food production and nutrient content to assess the implications of various crop-
shifting scenarios on consumptive water demand and nutrient production. We find that historical growth in wheat
production during the rabi (non-monsoon) season has been the main driver of the countrys increased consumptive
irrigation water demand and that rice is the least water-efficient cereal for the production of key nutrients, especially
for iron, zinc, and fiber. By replacing rice areas in each district with the alternative cereal (maize, finger millet, pearl
millet, or sorghum) with the lowest irrigation (blue) water footprint (WFP), we show that it is possible to reduce irri-
gation water demand by 33% and improve the production of protein (+1%), iron (+27%), and zinc (+13%) with only a
modest reduction in calories. Replacing rice areas with the lowest total (rainfall + irrigation) WFP alternative cereal or
the cereal with the highest nutritional yield (metric tons of protein per hectare or kilograms of iron per hectare) yielded
similar benefits. By adopting a similar multidimensional framework, India and other nations can identify food security
solutions that can achieve multiple sustainability goals simultaneously.
Global crop production has more than tripled since the 1960s, leading
to increased food supply per capita, lower food prices, and reduced mal-
nutrition worldwide (1). This remarkable growth in global food supply
has been accompanied by the depletion of freshwater resources for ir-
rigation (24), nutrient pollution from injudicious fertilizer application
(5,6), and rising greenhouse gas emissions (7,8). There is therefore
widespread agreement that agricultures use of planetary systems is un-
sustainable (913) and that humanity will need to feed an additional
2 billion people by 2050 while also minimizing the environmental
consequences of the global food system (1,14). Numerous studies have
explored strategies to resolve this food-environment dilemma [for ex-
ample, (1,7,11,13,14)], but little work has been done to examine nu-
tritional and environmental outcomes together or to identify concrete
policy pathways by which these solutions may be put into action within
specific countries. Given the immediacy of food security and sustain-
ability challenges around the world, incorporating these solutions by
leveraging a nations existing agricultural policies offers promise to bet-
ter link science with real-world outcomes.
The need for improved compatibility between food security and
environmental stewardship is of considerable urgency in India. The
worlds second most populous country, India, has remained largely
self-sufficient in terms of cereal production over the past 50 years, with
rice (grown during the kharif/monsoon season) and wheat (grown during
the rabi/winter season) as the flagship crops driving substantial increases
in food supply (15). While the boom in rice-wheat systems has vitally
contributed to reducing hunger and malnutrition throughout India
(16), these trends in production have been supported by ever-increasing
agricultural inputs and extensive environmental consequences, particu-
larly for freshwater resources. Many parts of the country now experience
chronic water stress due to heavy-water extraction for irrigated agricul-
ture (1719) and a weakening monsoon (2022), while widespread nu-
trient deficiencies persist (23,24). Because Indian diets generally derive a
large fraction of nutrients from cereals (25), these mounting food security
and environmental challenges make it increasingly clear that the rice-
wheat status quo of the Indian food system requires critical examination
and that solutions that integrate nutrition and the environmental impacts
of food production can offer pathways toward healthier food baskets with
less environmental burden (26).
Because India relies mainly on domestic production, the country
presents an excellent opportunity for examining how alterations of pro-
duction within the country could potentially benefit nutrition and water
use. Recent work [for example, (27,28)] has demonstrated the large in-
efficiencies present in food systems in terms of water use, showing the
possibility of planting crops with lower water requirements while also
enhancing calorie and protein production. Other studies in central In-
dia have examined water stress, land use, nutrition, and climate sensi-
tivity associated with cereal production and demonstrated that certain
cereals can offer distinct benefits over rice along all of these dimensions
(19,29,30). However, a national analysis of the potential nutritional and
water use benefits of alternative cereals (that is, maize, millets, and sor-
ghum) is still lacking for India.
To do this, we first examine how Indian cereal production has
changed through time, what this has meant for historical water use
and nutrient production, and how these dimensions might benefit from
alternative mixes of cereal crops. We limit our analysis to consider four
key nutrientscalories, protein, iron, and zincforwhichcerealsserve
as the major source in Indian diets (25). For each district, we first quan-
tify the water requirements [equal to the evapotranspiration from a crop
over a growing season; units are in millimeters of H
The Earth Institute, Columbia University, New York, NY 10025, USA.
The Nature Con-
servancy, New York, NY 10001, USA.
Department of Civil and Environment Engineer-
ing, Politecnico di Milano, Milan, Italy.
Indian School of Business, Hyderabad, India.
Sustainable Waters, Crozet, VA 22932, USA.
Lamont-Doherty Earth Observatory, Co-
lumbia University, Palisades, NY 10964, USA.
School of the Environment, Washington
State University, Vancouver, WA 99164, USA.
Department of Ecology, Evolution, and
Environmental Biology, Columbia University, New York, NY 10027, USA.
*Corresponding author. Email:
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 1of11
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(hereinafter mm H
India [rice (Oryza sativa), maize (Zea mays), wheat (Triticum aestivum),
sorghum (jowar; Sorghum vulgare), pearl millet (bajra; Pennisetum
typhoideum), and finger millet (ragi; Eleusine coracana)], using average
climate data for 2000 through 2009 and categorizing based on growing
season (kharif/monsoon for rice, maize, finger millet, and pearl millet;
rabi/winter for wheat; and both seasons for sorghum). We then com-
bine this information with historical production data (31)toestimate
crop demandthe product of crop water requirement (CWR) and har-
vested areafor green water (that is, rainfall) and blue water (that is,
irrigation required to avoid crop water stress) from 1966 through
2009. We also assess patterns of reliance on irrigation and water stress
to examine how they have shifted with increasing cereal production.
We then use this information to evaluate several replacement scenar-
ios in which rice areas in each district are instead planted with alternative
kharif cereals and, in doing so, we seek to examine whether food security
goals and improvements in freshwater use can be achieved in tandem.
These scenarios are motivated by two key objectives of the Indian govern-
ment, namely, to alleviate undernourishment by increasing the supply of
nutritious foods (32) and to promote sustainable water resource manage-
ment in agriculture (33). Specifically, we consider four primary district-
level scenarios aligning with these objectives by replacing rice-harvested
areas with (i) the lowest total water footprint (WFP) crop, (ii) the lowest
blue WFP crop, (iii) the crop with the highest nutritional yield in
terms of protein, and (iv) the crop with the highest nutritional yield in
terms of iron and quantify what the changes in water use and nutrient
production would be. Finally, we examine an important potential policy
leverIndias Public Distribution System (PDS)by which these transi-
tions toward alternative cereal production and consumption could be
realized. In doing all of this, we can determine where and to what extent
efforts to promote alternative mixes of cerealsfor which there is local
knowledge regarding cultivation and consumptioncould simulta-
neously improve water use efficiency and nutrient availability in diets.
CWRs showed substantial variation both between crops and geograph-
ically (units are in mm H
S1). As expected, we found that the highest total CWRs occurred for rice
and wheat and that demand for irrigation was more pronounced in arid
regions (for example, Rajasthan and Maharashtra; figs. S2 and S3). We
also observed high blue (irrigation) water requirements for all rabi
(non-monsoon, winter) crops as they must rely more heavily on irriga-
tion (Fig. 1).
Cereal production has grown by 230% from 1966 to 2009. Although
the combined production of alternative cereals (that is, those other than
rice and wheat) was larger than that of wheat in the 1960s, their relative
contribution to the cereal supply has steadily dwindled (fig. S4, A and
B). Yet, alternative cereals still disproportionately account for the supply
of protein, iron, and zinc among kharif crops (table S2 and fig. S5). At
the same time, total consumptive water demand for Indian cereal pro-
duction has increased from 482 to 632 km
during the study
period; this increase has been driven almost entirely by a doubling of
consumptive blue water demand for wheat during the rabi season
(Fig. 1) and modest increases in cropping frequencies and cropland
extent (fig. S4, C and D). Not surprisingly, the largest increases in
consumptive water demand occurred in the states of Punjab and
Haryana, where irrigated rice and wheat production now occurs at com-
mercial scales. The continuing transition to rice- and wheat-dominated
croplands has also increased the proportion of crop water demand met
through irrigation, especially in the countrys northern states (Fig. 2, A
to D). When comparing consumptive water demand to long-term av-
erage renewable water availability (that is, water generated from annu-
al precipitation), we also observed that many districts were already
experiencing substantial water stress at the beginning of the time pe-
riod and that the burden of water stress has shifted away from south-
ern districts, some of which have experienced a decrease in crop water
demand, and toward districts located largely in Punjab and Haryana
(Fig. 2, E and F).
We also examined the water productivities [that is, WFP; cubic
meters of H
O consumed per ton of crop produced (hereinafter,
O ton
)] of the different cereals for the production of key nu-
trients. When using the conventional metric of WFP, we found that rice
(1490 m
) was by far the most inefficient blue water user
among the kharif (monsoon) crops and that the total WFP of sorghum
grown during the rabi season was nearly double that of wheat (Fig. 3).
In addition, rice was the least productive water user among monsoon
cereals when examining nutrient production, rivaling rabi (winter)
Table 1. National average CWRs weighted by district production.
CWRs (mm H
O year
) were calculated for each district using averaged
climate variables covering the years 2000 through 2009. Green CWRs for
rainfed crops are consistently higher than for irrigated crops because of
differences in the distribution of rainfed (R) and irrigated (I) cereal pro-
duction. Values in parentheses are the production-weighted SDs. Ellipses
indicate that the crop is not produced during a particular season.
Kharif Rabi
Green (R) Green (I) Blue (I) Green (R) Green (I) Blue (I)
Rice 641 (160) 570 (157) 307 (126) 263 (47) 189 (52) 622 (162)
Wheat ……321 (57) 272 (50) 517 (91)
Maize 439 (48) 415 (45) 49 (47) 259 (38) 181 (36) 237 (46)
Sorghum 425 (59) 400 (56) 44 (42) 220 (72) 146 (54) 179 (42)
Finger millet 424 (39) 400 (30) 59 (78) ……
Pearl millet 314 (129) 296 (119) 46 (60) ……
Fig. 1. Time series of consumptive water demand for Indian cereal production.
Consumption is disaggregated between precipitation on rainfed lands [Green wa-
ter (R)], precipitation on irrigated lands [Green water (I)], and irrigation water on
irrigated lands (Blue water).
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 2of11
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crops in the volume of blue water requiredper ton of calories, protein,
and zinc production and surpassing all crops for water requirements
for iron production. Maize consistently performed well across all nu-
trient metrics, particularly with regard to irrigation water productivity.
Together with the inefficiencies of rice, these results indicate that
greater incorporation of alternative cereals into the Indian food system
can offer considerable potential benefits in terms of nutrition and wa-
ter use, although it is important to note that, due to relatively low
yields, sorghum, pearl millet, and finger millet showed potential
trade-offs between water productivity and land use efficiency. Com-
bined with the differing geographies and climates that these cereals
currently occupy (fig. S1), these considerations necessitated compar-
isons at finer scales as the relative ranking of crops can vary widely
between districts (fig. S6).
With these potential trade-offs between water, land, and nutrition in
mind, we considered multiple district-level rice replacement scenarios
aimed at reducing consumptive water demand for kharif (monsoon)
cereal production, improving nutrient production from cereals, and
conserving the extent of cultivated land, all of which are goals of the
Indian government. We first replaced rice areas with the kharif cereal
having the lowest total WFP in each respective district, provided that
the replacing crop had a total WFP (m
) lower than rice
(Fig. 4, A and E), and found that, in doing so, it is possible for India
to substantially reduce consumptive water demand (21% for green
water and 32% for blue water; fig. S7); increase protein (+9%), iron
(+43%), and zinc (+28%) supply; and maintain calorie (+1%) pro-
duction (Fig. 4I). Much of these benefits for water and nutrition
came from relatively few districts, with half of total water savings
for this scenario coming from just 39 districts (table S3). The districts
that stood to benefit the most in terms of reduced water demand were
also those largely responsible for increases in nutrient production. This
additional nutritional supply from this scenario could serve to address
persistent deficiencies, particularly for iron (table S4) (23,25), and could
help to compensate for insufficient nutrient supply from other food
groups of the Indian diet. Performing replacements based on blue
WFPs yielded similar results, although with a modest reduction in
calorie supply (scenario 2; Fig. 5A and table S4). For both of these
scenarios, we found that nutrient production would be more evenly
distributed across the country (as opposed to being concentrated in
Punjab and Haryana) and that the largest increases in nutrient pro-
duction generally occurred in eastern India (fig. S8).
We also considered two scenarios in which rice was replaced by the
alternative kharif cereal with the highest nutrition yieldin terms of
either protein or ironwithin each district (Fig. 4 and table S4). Both
scenarios yielded similar results to the minimum WFP scenarios, with
substantial improvements in water use and in protein, iron, and zinc
production but with mixed outcomes for calorie supply (maximum
protein, +8.7%; maximum iron, 4.5%; Fig. 4I). Overall, the benefits
of rice replacement across all scenarios were more pronounced within
rainfed croplands and were largely attributable to relatively few dis-
tricts (Fig. 5 and table S3). The modest calorie reductions that occurred
in two of the four replacement scenarios were largely because the
yields of alternative cereals were on average lower than those for rice
(fig. S9 and table S7). However, it is important to note that, of the 296
districts where rice is cultivated, there are many instances where
alternative cereals achieve higher yields relative to rice (8 for finger mil-
let, 139 for maize, 36 for pearl millet, and 55 for sorghum). In all, there
are 149 districts where at least one of the alternative cereals considered
here attained a higher yield than rice (table S6). The high yields and low
CWRs of maize relative to the other alternative cereals made it the
Fig. 2. District-level changes in total consumptive water demand for cerea l production, blue water fraction, and water stress. Total consumptive water demand for cereal
production is compared for the beginning of the study p eriod [(A) 19661970] and the end of the study period [(D) 20052009]. (Band E) Blue water fractions for the beginning and end of
the study period are the ratio of consumptive blue water use to total consumptive water use for cereal production. Availabilityisthe long-term (19702000)average of available renewable
water, which originates from annual precipitation and contributes to stream flow and groundwater recharge. (Cand F) If the ratio of consumptive water demand to annual availability
exceeds unity, then the difference must be met through nonrenewable sources and can lead to the depletion of freshwater resources (for example, through groundwater pumping).
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 3of11
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dominant replacement crop in two of the four scenarios (scenario 1:
lowest total WFP; scenario 3: highest protein yield; Fig. 4 and table
S4). In many parts of the country, maize is not traditionally consumed
to the same extent as millets and sorghum, and cultural preferences will
strongly determine the realistic possibilities for alternative cereals, which
may differ in certain places from those selected by some of our scenarios.
In view of this, we also imposed additional constraints on the replacement
scenarios (that is, nutritional yield of replacing crop in terms of calories
must be higher than rice and/or maize could not be considered as a
replacement) and generally observed the same benefits of replacement,
though of a smaller magnitude. In a few cases, trade-offs began to
emerge between water savings and nutrient supply at the national level,
highlighting the need for selective, well-considered, and location-specific
strategies to promote alternative cereals (table S4).
As a final note, information on actual irrigation water withdrawals in
India beyond country-level estimates is not available (34). As such, our
study examines blue water demand and potential blue water savings, an
approach that is widely used to compare the water use intensities of dif-
ferent crops and to provide insights into less water-demanding cropping
choices (3,18,28,3538). Depending on pumping capacity and irriga-
tion source for an irrigated field, a farmers actual irrigation availability
may fall below a crops irrigation water requirement (that is, the volume
of irrigation water required to prevent crop water stress) and would
mean that a crop shift may in reality realize lower or no blue water sav-
ings. However, in many cases, a transition to a crop that requires less
irrigation water will not only result in real water savings but also leave a
farmers crops less exposed to potential water stress.
A substantial increase in rice-wheat cropping, a system that depends
heavily on irrigation, has contributed to chronic water stress in many
parts of India (Fig. 2). There is widespread consensus (17,3941)that
these current practices, in combination with weakening monsoonal
rains (20,22), offer little possibility of long-term sustainability for water
use if India intends to continue to meet its cereal demand domestically.
Even for countries expecting little population growth in the coming dec-
ades, policies of food self-sufficiency can present substantial food-water
trade-offs. For instance, a recent study of neighboring Sri Lanka showed
that the countrysfreshwaterresourceswillbeinsufficient to sustainably
supply the irrigation water required to continue maintaining rice pro-
duction above domestic demand (42). For a country such as India,
which will need to feed a projected 394 million more people by 2050
(43), the potential for undesirable trade-offs between food security
Fig. 3. Water productivity (m
O) of nutrient production for total, blue, and green WFPs. Values correspond to the years 2000 through 2009 and represent the ratio
of conventional WFPs on irrigated cropland [(A) that is, m
O ton
] to nutrient content (that is, amount of nutrient per ton of crop) for (B) calories, (C) protein, (D) iron, and
(E) zinc. Blue fraction (F) is the ratio of blue WFP to total WFP.
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 4of11
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and environmental sustainability is profound. Yet, our findings demon-
strate that India can alleviate these difficult decisions by exercising flex-
ibility in the types of cereals it produces and consumes.
Recent decades in India have shown that widespread changes in ce-
real mixes are possible within relatively short time periods. While there is
still considerable consumption of alternative cereals in certain regions of
the country (fig. S10), the continuing shift toward rice-wheat cropping
and consumption indicates a substantial influence from the countrys
PDS (44), a program that leverages the countrys tight linkages between
food production and diets to promote food security for low-income
households and livelihood support for smallholder farmers. By providing
a guaranteed Minimum Support Price to producers and placing heavy
subsidies on rice and wheat at the consumer end, this system has also
served to influence cropping and dietary choices away from more
nutrient-rich alternative cereals and is an important factor contributing
to the persistence of widespread nutrient deficiencies (25,44).
By using similar policy mechanisms to transition to a greater reliance
on other cereals, India can potentially realize important benefits in terms
of both reduced consumptive irrigation water demand and increased
production of key nutrients. Of course, there are multiple factors that
dictate a farmers crop choice and a households consumption basket,
and some of the reasons that producers and consumers may prefer rice
and wheat may be difficult to influence. These considerations are essen-
tial for identifying where efforts aimed at increasing alternative grains
may complement local priorities and preferences. With these very real
challenges in mind, certain states (for example, Karnataka and Odisha)
have initiated state-level pilot programs that will procure selected alternative
cereals from farmers under their PDS programs. The removal of these
Fig. 4. Outcomes of selected rice replacement scenarios. Maps show the districts in which rice-harvested areas were replaced by kharif crop with (Aand E) the lowest
total WFP in each district(scenario 1), (Band F) the lowestblue WFP in each district (scenario 2), (Cand G) the highestnutritional yield in termsof protein (metric tons of protein
per hectare), and (Dand H) the highestnutritional yield in terms of iron(kilograms of iron per hectare). (I)Solid columns correspond toirrigated areas, and patterned columns
correspond to rainfed areas. Values are reported as percent changes relative to current levels of water demand and nutrient supply. Changes in water demand are separate
between blue water (blue) andgreen water (green). Becausewe made no replacements in rainfed rice areas under the replacement scenariobased on blue WFPs (scenario 2),
there are no rainfed bars for this scenario. Current levels of water demand and nutrient production and the levels of minimum nutrient production required from cereals to
meet daily recommended intake (DRI) for the country (if there were no limitations on access and distribution and no losses or waste) (23) are reported in tables S2 and S3.
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 5of11
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economic barriers (by which government procurement is only offered for
rice and wheat) will therefore provide invaluable information on the will-
ingness of farmers and households to increase alternative cereals in their
production and consumption baskets.
It is clear that further work is needed to fully understand the suite of
factors influencing cropping and dietary choices and their economic,
nutritional, and environmental implications, and this study addresses
potential benefits of transitioning toward alternative cereals exist for
bothrainfedandirrigatedsystems,where substantial reductions in con-
sumptive water demand are complemented by increased nutrient pro-
duction (table S4). In addition, by improving water productivity for
cereal production during the kharif (monsoon) growing season, more
freshwater may be made available for rabi irrigation as well as for
environmental flows and domestic, municipal, and industrial uses. Fur-
ther, incorporation of alternative, less water-demanding cereals can help
to increase crop diversity in Indian cereal production and reduce vul-
nerability to dry spells in places where freshwater resources for supple-
mentary irrigation may be less readily accessible and can potentially
enhance the resilience of the food system against future uncertainties
associated with climate change [for example, (30)].
Our replacement scenarios also demonstrate that efforts at
improving alternative cereal production can help to more equally
distribute nutrient production across the country and thereby reduce
the impact of a single local climate shock to national grain production.
This decentralization of nutrient productionaway from Punjab and
Haryanathat these alternative cereals would afford would also repre-
sent a reversal of the trend in which cereal production (fig. S11) and
water consumption have shifted away from southern states and served
to enhance already existing water stress in the north (Fig. 2).
The potential food-water benefits demonstrated in this study were
all realized while maintaining the current extent of cropland (that is, no
agricultural expansion). Such a consideration is vital in a country with
high population density and intensive pressure on land resources. Al-
though we were able to constrain cultivated area, in certain cases, we
found that important trade-offs exist between efficient land and water
use for nutrient production (fig. S9) and that the magnitude of potential
benefits from rice replacement and the choice of alternative crop varied
widely between districts (fig. S6B and Fig. 4). While all replacement sce-
narios generally realized benefits for water use and nutrient supply, even
a slight reduction (as occurred in certain cases for calories) may not be
an acceptable outcome for a country in which nutrient supply is generally
Fig. 5. Cumulative water savings and changes in nutritional output. For each rice replacement scenario (Sc1, Sc2, Sc3, and Sc4), districts were ranked based on
volume of water savings from smallest to largest and plotted against their associated changes in the supply of (A) calories, (B) protein, (C) iron, and (D) zinc.
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 6of11
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inadequate. Thus, in a country such as India, where a high fraction
of people continue to be undernourished, policy-makers may seek to
selectively encourage the production and consumption of alternative
cereals only where these undesirable trade-offs will not occur. In the
near term, efforts at altering the mix of cereal production should focus
on those states in which farmers are already able to achieve relatively
high yields for alternative cereals, thereby avoiding any undesirable out-
comes for nutrient production, particularly for calories. Many of the
trade-offs between nutrient supply and water use efficiency can be
eliminated by focusing agricultural research on further improving yields
of these alternative cereals and would almost certainly ensure greater
improvements in nutrient production as well. Yet, even with these rel-
erally contributed to reductions in consumptive water demand and
improvements in nutrient production under the rice replacement sce-
narios considered in this study (Fig. 5).
There are certainly a host of other considerations, beyond water and
land use and nutrient production, that factor into agricultural policy
and consumer choices, and the crops, environmental impacts, and nu-
trients included in such an analysis must be selected according to each
situation. For Indian cereals in particular, there are several aspects of
production and consumption that our analysis does not include but
which are important for fully understanding the nutritional, economic,
and environmental implications of shifting cropping patterns. As one
example, rice residues serve as an important source of animal fodder,
and animal products in turn provide key sources of protein and iron to
alternative cereals (and their residues) can readily be used as feed and
fodder, that their nutritional qualities as feed and fodder exceed that of
rice and rice residues, and that their use to support animal production
already occurs across India [for example, (4552)].
Further studies on dimensions such as greenhouse gas emissions and
input costs, storage and transport costs, labor requirements, and dietary
preferences are also required before any policy recommendations can
responsibly be made. Studies that incorporate optimization approaches
to develop trade-off frontiers can also help to reconcile these multiple
objectives. While future work on these other factors is still needed, the
cereals considered here offer great promise for improving water use and
nutrient production while conserving agricultural extent. As such, the
holistic approach that we have presented, in which multiple dimensions
are considered in tandem, provides a mechanism for incorporating oth-
er economic and cultural dimensions into an integrated framework for
sustainable decision-making. The outcome of this study demonstrates
that nutrition and environmental outcomes need to be considered
together, that existing policies can be used to achieve food-environment
co-benefits in one of the worlds most populous countries, and, more
generally, that solutions for achieving sustainable intensification in
any country are most effectively achieved if based on analyses of
trade-offs and synergies across multiple dimensions.
Nations are increasingly facing challenges of increasing food production
while simultaneously minimizing resource use and environmental im-
pacts. This is certainly the case for India where historical trends in cereal
production have contributed to widespread water stress and nutrient
deficiency. Our study demonstrates that replacing rice with other cer-
eals, for which local knowledge on their production and consumption
already exists, can offer distinct benefits in terms of both reducing
freshwater use and enhancing nutrient production. This case study of
India provides an example of how a multidimensional approach can be
used in other places to assess sustainability goals at the interface of food
security and the environment, to understand and avoid undesirable
trade-offs, and to better link science with policy.
We examined the water use and nutrient content of rice (O. sativa),
maize (Z. mays), wheat (T. aestivum), sorghum (jowar; S. vulgare), pearl
millet (bajra; P. typhoideum), and finger millet (ragi; E. coracana), which
constitute nearly all of Indias cereal production (15). Data on district-
and crop-specific production, harvested area, and irrigated area were
taken from the International Crops Research Institute for the Semi-Arid
Tropics Village Dynamics in South Asia (VDSA) mesoscale data set
(31). These data are reported annually for the years 1966 through
2011 and use 1966 district boundaries. Data for the years 2010 and
2011 were incomplete and were not included in this study. While there
has been substantial modification to district boundaries since 1966, the
data provided in VDSA currently cover 593 of Indias 707 districts and
87% of the countrys land area. National values for nutrient content
were taken from the newly released Indian Food Composition Tables
(table S8) (53). Year 2011 district-level consumption data for each cereal
came from the Indian National Sample Survey (table S6) (24). National
DRI values for calories, protein, iron, and zinc came from IndiasNa-
tional Institute of Nutrition (23).
Information on actual water withdrawals or pumping rates is not
available for India, and estimations of CWRs provide the best alternative
in examining the water needs of farmers across the country. CWRs were
calculated for each district at monthly time steps for the years 2000
through 2009 and were split between blueand greenCWRs, where
green water is supplied through rainfall and blue water is supplied
through irrigation (2). Blue water represents a crops consumptive water
demand in excess of what is provided through precipitation and is only
used in calculations of consumptive water demand within irrigated
areas. In reality, farmers with access to irrigation may not be able to fully
meet the irrigation water demand of their crops, as limited by pumping
rates and irrigation source. This means that, if a farmer pumped at max-
imum capacity but was still unable to obtain sufficient irrigation water
to meet the blue water requirement of any of the crops considered here,
the actual water use for the field would not change. For those farms where
irrigation availability is only insufficient for the most water-intensive
cereals, a shift to crops with lower water requirements will result in an
actual reduction in irrigation water use. It is also clear that, if a farmer
transitions to a crop with a lower blue water requirement, regardless of
the irrigation water available to that field, this crop will be less exposed
Precipitation data came from the Indian Meteorological Depart-
ments daily rainfall product (1.0° × 1.0°) (54). Mean daily temperatures
were taken from the University of East Anglias Climate Research Unit
Time Series version 3.24.01 data set (0.5° × 0.5°) (55). Monthly wind
speed and relative humidity data came from the National Oceanic and
Atmospheric Administration/Oceanic and Atmospheric Research/Earth
System Research Laboratory Physical Sciences Divisions National
Centers for Environmental Prediction Reanalysis product (2.5° × 2.5°)
(56). Soil information (sand, silt, and clay fractions) came from the In-
ternational Soil Reference and Information Centres30arc sec SoilGrids
database (57). Data for net radiation at the surface (which also accounts
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 7of11
on July 4, 2018 from
for soil heat flux density) were taken from NASAs Global Land Data
Assimilation System Noah Land Surface Model L4 monthly, Version 2.0
(0.25° × 0.25°) (58). Crop coefficients, climate zones, and growing stages
were adapted from Mekonnen and Hoekstra (35) and Kottek et al.(59)
(table S9 and fig. S12). State-level planting dates were determined by
combining information from the Indian Meteorological Department
(60), Portmann et al.(61), and Mekonnen and Hoekstra (35)(table
S10). Growing stages for each district were shifted to align with both
the crop coefficient values for the particular climate zone in which that
district was located and the estimated planting date of that districts
state. The same values for crop coefficients, growing stages, and planting
dates were used for both pearl millet (bajra) and finger millet (ragi).
Estimating atmospheric demands on crops
Reference evapotranspiration, ET
, was calculated for each district at
monthly time steps using the Food and Agriculture Organization of
the United NationsPenman-Monteith equation (36)
Tþ273 u2ðeseaÞ
where R
is the net radiation at the crop surface (MJ m
); Gis the
soil heat flux density (MJ m
); Tis the mean daily air tempera-
ture at 2 m (°C); u
is the wind speed at 2 m (m s
); e
and e
are the
saturation and deficit vapor pressures, respectively (kPa); Dis the slope
vapor pressure curve (kPa°C
); and gis the pyschrometric constant
). The actual evapotranspiration (ET
)ofcropion day twas
then calculated as
where k
is the crop coefficient of crop icorresponding to the month
in which day toccurs (table S9) and k
is the water stress coefficient
calculated following Allen et al.(36) as a function of the soil water con-
tent in the root zone (S
), the maximum and actual water content in the
root zone. Rooting depths for irrigated and rainfed crops came from
Siebert and Döll (37)(tableS11).Forcropion day tunder water-stressed
conditions (that is, when only precipitation was provided), k
evaluated as
if Si;t<ð1piÞSmax;i
where S
is the depth-average soil moisture (expressed as a length),
is the value of available soil moisture, and p
is the fraction of
that a crop can uptake from the rooting zone as calculated in
Allen et al.(36) and Siebert and Döll (37). For conditions of no water
stress (where supplementary irrigation is available), k
was as-
sumed to be 1 (35,37). For a given crop and grid cell, soil moisture
) was calculated by solving a daily soil water balance
where S
is the soil moisture of the previous time step, Dtis equal
to 1 day, P
is the effective precipitation (that is, the rainfall that is
actually absorbed in the soil and not directly evaporated from the
surface), I
is the additional irrigation water (used only in the case
of irrigated crops), and D
is deep percolation below the root zone
(which occurred when soil moisture exceeded field capacity, that is,
the volume of water that can be retained in the soil). Daily precipi-
tation was converted to P
using the Soil Conservation Service
method [see, for example, (35,36,62)].
Thus, for each day, each crop, and each district, we were able to
calculate a stressed ET
(equal to the green consumptive water use)
and unstressed ET
(equal to the actual evapotranspiration under
no water stressed). Blue consumptive water use was calculated as the
difference between ET
and ET
and was only considered for
irrigated areas. We then took a summation of the daily green and blue
consumptive water use across a crops entire growing season to deter-
mine total green (for rainfed and irrigated crops) and blue (for irri-
gated crops only) consumptive CWR, averaged across the years 2000
through 2009 (table S1). These definitions of green and blue consump-
tive water use are consistent with standard methodologies of WFP
calculation [for example, (35)].
Estimating historical consumptive water demand and
water stress
Green consumptive water demand (CWD
) for cereal production
was estimated annually for each district jas
where CWR
is the green CWR (mm H
rainfed area (ha) in district j(calculated as the difference between har-
vested area and irrigated area), and the factor of 10 ensures that the
units are in cubic meters of H
O per year. This calculation was re-
peated using the blue CWR and crop-specific irrigated area to deter-
mine the consumptive (blue) irrigation water demand. The irrigated
area data from VDSA had some missing values, which we linearly in-
terpolated. If data were missing at the beginning or end of the time
period, then these values were linearly extrapolated based on the im-
mediately succeeding or preceding 10 years, respectively. Complete data
for crop-specific district-level irrigated area in West Bengal were only
available for the years 1966, 1967, 1983, 1985, and 1988 from VDSA.
To ensure that our estimates were conservative, we took the ratio of
irrigated area to harvested area for each of these years, averaged these
ratios across the 5 years of available data, and applied this constant
irrigated/harvested ratio to all years. Because the VDSA crop produc-
tion data set does not distinguish between kharif and rabi production
for rice, maize, pearl millet, and finger millet, we used the CWRs for
the kharif season for these crops to estimate total consumptive water
demand. This assumption is supported by crop production data re-
ported by season from the Directorate for Economics and Statistics
(63), which shows that millet production during rabi is negligible
and that only for selected states (for example, rice in Andhra Pradesh,
Odisha, Tamil Nadu, and West Bengal, and maize in Andhra Pradesh,
Bihar, Madhya Pradesh, and Tamil Nadu) is rabi production substan-
tial for rice or maize. Wheat is exclusively produced during the rabi
season with certain states producing small amounts of cereals outside
of the kharif and rabi growing seasons.
Water stress was calculated as the ratio of total consumptive water
demand for cereals to the long-term average renewable water availability
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 8of11
on July 4, 2018 from
for each district. Watershed-level data on renewable water availability
(surface + groundwater) cover the years 1970 through 2000 and came
from Brauman et al.(4) who used the WaterGAP3 integrated global
water resources model. These data do not account for interbasin
transfers or desalination. Brauman et al.(4)defineavailable
renewable water as water generated [from precipitation] within
the watershed and inflows from upstream that are stored or pass
through rivers or move from the land surface into aquifers (renewable
groundwater).Using long-term average renewable availability allows
for an examination of whether freshwater withdrawals and consump-
tion can be sustained by a watershed through time. If consumptive
water demand consistently exceeds the average renewable water avail-
able (and that is able to recharge annually), then the difference must
be met through nonrenewable sources (for example, groundwater
pumping) and can lead to the depletion of surface and groundwater
Replacing rice with alternative cereals
Rice replacement scenarios were based on the years 2000 through 2009
to align with the time period used for WFP calculations. Replacements
were carried out separately for rainfedandirrigatedcroplands.Under
all replacement scenarios, we assumed that the water resources available
to rice fields would then become available to the replacing crop. To
explore how increased production of alternative cereals may benefit
outcomes for water demand and nutrient production, we examined
four district-level scenarios by replacing rice in rainfed and irrigated
areas with (i) the alternative cereal with the lowest total WFP, (ii) the
alternative cereal with the lowest blue WFP, (iii) the alternative cereal
with the highest nutritional yield in terms of protein (metric tons of
protein per hectare), and (iv) the alternative cereal with the highest
nutritional yield in terms of iron (kilograms of iron per hectare). For
rainfed areas in scenario 1, green WFP was equal to total WFP. By
replacing rice-harvested areas (instead of rice production), we were
able to conserve agricultural extent and avoid any agricultural exten-
sification. For scenario 1, the alternative cereal with the lowest total
WFP in a given district replaced rainfed rice. If this crop had a total
WFP higher than that of rice, then no replacement occurred for
rainfed rice areas in that district. This scenario was applied separately
to irrigated rice areas. For scenario 2, the alternative cereal with the
lowest blue WFP in a given district replaced irrigated rice. If this crop
had a blue WFP higher than that of rice, then no replacement
occurred for irrigated rice areas in that district. This scenario was
not applied to rainfed rice areas. For scenario 3 and scenario 4, the
alternative cereal with the highest nutritional yield (in either protein
or iron, respectively) replaced rainfed rice, provided that the nutritional
yield of the replacing crop was higher than that of rice. Additional
supplementary constraints were also applied to all of the scenarios
described above (table S4). These constraints were that a rice repla-
cement could only occur if the replacing crop also had a nutritional
yield in terms of calories (kilocalories per hectare) that was higher
than that of rice and/or that only finger millet, pearl millet, or sorghum
could be considered as replacing crops. In all replacement scenarios,
we assume that the water resources available to rice are then made
available to the replacing crop.
Combining water use and nutrition
The conventional measure of WFP uses the units of cubic meters of
consumptive water demand per ton (for example, m
(58). To examine whether the relative ranking of crops changed in terms
of water productivity, we calculated the nutritional WFP values of crop i
in district jas
where p
is production (metric tons) and c
is the crop content of
nutrient n(nutrient per ton of crop). We used the nutrient content values
reported for the most consumed form of each crop (table S8). Under all
scenarios, the production of nutrient nin district jwas calculated as
where y
is the yield of crop iand a
is the intended (irrigated or
rainfed) area for crop i. Total minimum nutrient production required
to meet DRI for the country (if there were no limitations on access and
distribution and no losses or waste) was calculated by Rao et al.(25)
2011 population statistics. Minimum required nutrient supply from
cereals was then calculated as the product of total minimum required
nutrient production for the entire Indian diet and the fraction of nutri-
ents provided by cereals under current consumption patterns (table S4)
(25). The minimum required nutrient supply used here assumes no lim-
itations on access and distribution and no losses or waste; actual nutri-
ent supply within the country would need to be above these values to
overcome these barriers. DRI values were not provided for dietary fiber.
Supplementary material for this article is available at
Table S1. CWRs by district (mm H
O year
) for rainfed and irrigated crops.
Table S2. National production changes for kharif (monsoon) cereals under replacement scenarios.
Table S3. Cumulative water savings and changes in nutritional output from replacement scenarios.
Table S4. Outcomes and descriptions of rice replacement scenarios.
Table S5. Cereal consumption by crop and by district.
Table S6. State-level yields of kharif crops and outcomes of rice replacement scenarios.
Table S7. Crop-specific nutrient content reported in the National Institute of Nutritions Indian
Food Composition Tables.
Table S8. List of crop coefficient (k
) values disaggregated by crop, climate zone, and month.
Table S9. State-level planting dates (month) for each cereal crop and growing season.
Table S10. Rooting depths for rainfed and irrigated crops as reported by Siebert and Döll (37).
Fig. S1. Geographic distribution of total CWR (mm H
) of Indian cereals in irrigated lands.
Fig. S2. Geographic distribution of the fraction of total CWR of Indian cereals in irrigated lands
met by blue water.
Fig. S3. Map of states based on 1966 boundaries.
Fig. S4. Time series of Indian cereal production and extent.
Fig. S5. Kharif production fractions by crop.
Fig. S6. Comparison of blue water use and nutrient yields of kharif (monsoon) cereals.
Fig. S7. District-level water savings of scenario 1 (rice replacement with the lowest total
WFP cereal).
Fig. S8. Changes in nutrient production under scenario 1 (lowest total WFP).
Fig. S9. Current rice yield and yield differences of replacing crop on irrigated croplands.
Fig. S10. Ratio of most consumed alternative kharif cereal to rice.
Fig. S11. Iron as an example of change in per-capita nutrient production.
Fig. S12. Map of climate zones.
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63. Directorate of Economics and Statistics, State of Indian Agriculture 2015-16 (Ministry of
Agriculture and Farmers Welfare, 2016).
Acknowledgments: We thank A. Dutta for help with summarizing the National Sample Survey
data, B. Sacks and F. Portmann for providing information on planting dates, and N. Rao
and J. Min for providing estimates of total minimum required nutrient supply. Funding: This
work was supported by The Nature Conservancys NatureNet Science Fellowship.
Author contributions: K.F.D., D.D.C., A.C., B.R., D.S., and R.D. gathered the data. K.F.D., D.D.C.,
and M.C.R. performed the CWR analysis. K.F.D., A.C., and R.D. analyzed the data. All authors
wrote the manuscript. Competing interests: The authors declare that they have no
competing interests. Data and materials availability: All data needed to evaluate the
conclusions in the paper are present in the paper and/or the Supplementary Materials.
Additional data related to this paper may be requested from the authors.
Submitted 14 June 2017
Accepted 29 May 2018
Published 4 July 2018
Citation: K. F. Davis, D. D. Chiarelli, M. C. Rulli, A. Chhatre, B. Richter, D. Singh, R. DeFries,
Alternative cereals can improve water use and nutrient supply in India. Sci. Adv. 4,
eaao1108 (2018).
Davis et al., Sci. Adv. 2018;4: eaao1108 4 July 2018 11 of 11
on July 4, 2018 from
Alternative cereals can improve water use and nutrient supply in India
Kyle Frankel Davis, Davide Danilo Chiarelli, Maria Cristina Rulli, Ashwini Chhatre, Brian Richter, Deepti Singh and Ruth
DOI: 10.1126/sciadv.aao1108
(7), eaao1108.4Sci Adv
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... A central question is whether a shift in grain procurement by the Government could economically achieve the national food security targets while addressing groundwater stress, the highly variable climate, and be economically feasible. Recently, Davis et al. 12,13 illustrated that India could improve water use and nutrition by shifting crops. This confirms our earlier results for purely rain-fed agriculture 14,15 . ...
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Significant groundwater depletion in regions where grains are procured for public distribution is a primary sustainability challenge in India. We identify specific changes in the Indian Government’s Procurement & Distribution System as a primary solution lever. Irrigation, using groundwater, facilitated by subsidized electricity, is seen as vital for meeting India’s food security goals. Using over a century of daily climate data and recent spatially detailed economic, crop yield, and related parameters, we use an optimization model to show that by shifting the geographies where crops are procured from and grown, the government’s procurement targets could be met on average even without irrigation, while increasing net farm income and arresting groundwater depletion. Allowing irrigation increases the average net farm income by 30%. The associated reduction in electricity subsidies in areas with significant groundwater depletion can help offset the needed spatial re-distribution of farm income, a key political obstacle to changes in the procurement system. Using optimization models with climate, crop & economic data, the authors show that India can stop groundwater depletion, reduce energy use and meet food/nutrition targets by changing where it sources crops for its food procurement and distribution system.
... Under low mitigation scenarios, agricultural changes are required to avoid production decreases. A transition to shorter growing seasons or other, more heat resistant, crops should be considered to cope with the temperature increases (Davis et al., 2018;Teixeira et al., 2013), especially for wheat. Development of heat resistant and high yielding crop varieties will also reduce production diminution (Bita and Gerats, 2013;Bustos et al., 2013;Gulnaz et al., 2019;Wu et al., 2019). ...
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Future irrigated agriculture will be strongly affected by climate change and agricultural management. However, the extent that agricultural management adaptation can counterbalance negative climate-change impacts and achieve sustainable agricultural production remains poorly quantified. Such quantification is especially important for the Indus basin, as irrigated agriculture is essential for its food security and will be highly affected by increasing temperatures and changing water availability. Our study quantified these effects for several climate-change mitigation scenarios and agricultural management-adaptation strategies using the state-of-the-art VIC-WOFOST hydrology–crop model. Our results show that by the 2030s, management adaptation through improved nutrient availability and constrained irrigation will be sufficient to achieve sustainable and increased agricultural production. However, by the 2080s agricultural productivity will strongly depend on worldwide climate-change mitigation efforts. Especially under limited climate-change mitigation, management adaptation will be insufficient to compensate the severe production losses due to heat stress. Our study clearly indicates the limits to management adaptation in the Indus basin, and only further adaptation or strong worldwide climate-change mitigation will secure the Indus’ food productivity.
... One study that has addressed the same issue as the present paper was that by Davis et al. (2018): 33 how to use water more efficiently while enhancing nutrient production. Using the concept of water footprint, it explored the shifts in cropping patterns from the dominant wheat-rice system to alternative crops including maize, jowar, ragi, and bajra. ...
... This is particularly true in India where the scale effect (Alley et al., 2018) is enormous, as captured in major groundwater irrigated state's agriculture pump connections and energy use ( Figure S2 in Supporting Information S1). As such, improvement in water management efficiency at the district scale is essential for food security in India (Davis et al., 2018;Joshi et al., 2021). But neither GRACE data nor the shallow-well dominated (>80%) monitoring network appear sufficient to provide the needed information. ...
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Characterizing local to regional scale water cycles and water resources will be crucial for achieving the United Nations' water‐related Sustainable Developmental Goals. However, quantification and understanding of groundwater extraction across scales have been hampered by inadequate water usage reporting and limited information on irrigation practices. Here we analyze observations from ∼15,000 groundwater monitoring wells and the Gravity Recovery and Climate Experiment satellites together with irrigation, agricultural, and meteorological datasets to show how drought‐induced coupling between natural and anthropogenic groundwater storage variations has caused sustainability challenges in India, the world's biggest consumer of groundwater for irrigation. Notably, the mechanisms and consequences of such coupling differ significantly depending on aquifer types. In Andhra Pradesh's hard rock aquifer, groundwater declines have been limited, despite the nearly constant water scarcity that its farmers face. Moreover, its free farm power policy involves an annual irrigation energy consumption of 26 billion kWh that costs US$ 2.5 billion, possibly unparalleled compared to any other part of the world of similar size (0.27 million km²). In West Bengal's highly permeable alluvial aquifer, the water table is declining rapidly (15 cm/yr) due to a policy that encourages irrigation. Situated between these two states, Odisha's aquifer shows substantial resilience to drought, owing to the state's relatively natural landscape and forest restoration policy. The findings of this study provide new insights to understand the divergent aspects of groundwater irrigation in north versus south India, which can enable development of adaptation and mitigation strategies to avert the looming water crisis.
... Another way to improve water use and also simultaneously the nutrient intake is by cultivating alternate cereals like maize, finger millet, pearl millet etc. than rice and wheat. Davis et al. (2018) have shown that if rice as a staple crop could be replaced by the other cereals mentioned before, then the irrigation water demand can be replaced by 33% Figure 4. Variation of water productivity across districts in India. Source: Amarasinghe (2012) while increasing the intake of protein, iron and zinc by 1%, 27% and 13%, respectively. ...
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India is endowed with several indigenous foods (IFs), that hold special cultural significance among local and ethnic caommunities, yet no attempts have been made till date to systematically compile their nutritive values. As per FAO's recent mandate on creation of “Global-Hub on Indigenous Food Systems,” IFs have received renewed global recognition for their potential to contribute to improved food security while enhancing biodiversity across the world. Hence, the useful properties of wild IFs require proper study and documentation in order to bridge the gap between scientific evidence generation and indigenous peoples' ancestral knowledge. For this purpose, we conducted a literature search in two scientific databases: PubMed and Google Scholar, between July 2020 and December 2021, to identify studies reporting nutritive values and/or antinutrient content of IFs (not included in Indian food composition database), consumed by Indian indigenous communities. A total of 52 Indian research articles were included, from which data was selected and extracted, to create a compendium on nutrient (n = 508) and antinutrient (n = 123) content of IFs, followed by computation of antinutrient-to-mineral molar ratios for 98 IFs to predict their mineral bioavailability. Maximum nutritive values were available for green leafy vegetables (n = 154), followed by other vegetables (n = 98), fruits (n = 66), cereals (n = 63), roots & tubers (n = 51) and nuts and legumes (n = 36). Several IFs seen to have better nutritional content than conventional foods and were found to be rich (i.e., >20% Indian recommended dietary allowances per reference food serve) in iron (54%), calcium (35%), protein (30%), vitamin C (27%), vitamin A (18%), zinc (14%) and folate (13%). Some IFs displayed high levels of antinutrients, however, anti-nutrient-to-mineral molar ratios were found to be low (for mainly leafy vegetables, other vegetables, and roots and tubers), thus indicating high mineral bioavailability. Hence, efforts are desirable to encourage the inclusion of these nutritionally superior IFs into the usual diets of indigenous communities. The IF database collated in our review can serve as a resource for researchers and policymakers to better understand the nutritional properties of region-specific IFs and promote them through contextual food-based interventions for improved dietary quality and nutrition outcomes in indigenous population of India.
Climate change poses a serious threat to crop productivity. The rise in CO2 levels, air temperature, soil salinity and variability in precipitation are the key factors that contribute to yield loss. Sorghum stands in the arid and semi-arid regions of the world that are particularly vulnerable to climate change. A comprehensive assessment of its vulnerability and resilience is required to adopt appropriate mitigation strategies. Here, we provide an overview of the projected and observed impact of the rise in temperature, CO2, salinity, drought and flooding stress on plant physiology, growth and development, and overall productivity of sorghum. While an increase in CO2 has been projected to enhance sorghum yields, a decrease in precipitation along with temperature rise would negatively impact sorghum productivity. Although sorghum is moderately tolerant to salinity and waterlogging, screening of germplasm for selection of improved varieties and development of tolerant cultivars is necessary for superior performance. The best agricultural practices, technological advances, and genetic enhancement desirable to mitigate the impact of climate change on sorghum productivity have been discussed. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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It has been projected that by the year 2050, the global population will reach 9.3 billion. By implication, this means that food production has to increase from 8.4 billion tonnes to 13.4 billion tonnes in order to keep pace with this increase (Food and Agriculture Organization of the United Nations, 2014), and also, that the already existing land, water, and energy crisis will possibly get further intensified. The crucial question is: Are we ready to deal with this? Clearly, we are amidst an agricultural crisis, wherein the ability of agriculture to fulfil human needs is threatened by factors such as climate change, loss of biodiversity, land degradation through soil erosion, compaction, salinization and pollution, depletion and pollution of water resources, rising production costs, poverty and a decrease of the rural population (Velten et al., 2015).
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The EAT–Lancet Commission has proposed a global benchmark diet to guide the shift towards healthy and sustainable dietary patterns. Yet it is unclear whether consumers’ choices are convergent with those guidelines. Applying an advanced statistical analysis, we mapped the diet gap of 15 essential foods in 172 countries from 1961 to 2018. We found that countries at the highest level of development have an above-optimal consumption of animal products, fats and sugars but a sub-optimal consumption of legumes, nuts and fruits. Countries suffering from limited socio-economic progress primarily rely on carbohydrates and starchy roots. Globally, a gradual change towards healthy and sustainable dietary targets can be observed for seafood, milk products, poultry and vegetable oils. We show that if all countries adopted the EAT–Lancet diet, the water footprint would fall by 12% at a global level but increase for nearly 40% of the world’s population. The pace of dietary shifts towards the EAT–Lancet dietary guidelines varies widely across countries. By analysing the supply of 15 essential foods in 172 countries over almost six decades, this Article estimates the level of convergence of national diets with the EAT–Lancet reference diet and the impact that closing such a diet gap would have on national and global water footprints.
This paper studies the impact of climate change on the nutritional status of very young children between the ages of 0–3 years by using weather data from the last half century merged with rich information on child, mother, and household characteristics in rural coastal Bangladesh. We evaluate the health consequences of rising temperature and relative humidity and varying rainfall jointly employing alternate functional forms. Leveraging models that control for annual trends and location-specific seasonality, and that allow the impacts of temperature to vary non-parametrically while rainfall and humidity have flexible non-linear forms, we find that temperatures that exceed 25 °C (the “comfortable” benchmark) in the month of birth exert negative effects on children's nutritional status as measured by mid upper arm circumference. Humidity has a positive impact which persists when child, mother and household controls are included. We find that exposure to changing climate in utero also matters. Explanations for these results include consequences of weather fluctuations on the extent of pasture, cropland, and rainfed lands planted with rice and other crops, and on mother's age at first marriage. Our results underline that climate change has real consequences for the health of very young populations in vulnerable areas.
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Growing demand for agricultural commodities for food, fuel and other uses is expected to be met through an intensification of production on lands that are currently under cultivation. Intensification typically entails investments in modern technology — such as irrigation or fertilizers — and increases in cropping frequency in regions suitable for multiple growing seasons. Here we combine a process-based crop water model with maps of spatially interpolated yields for 14 major food crops to identify potential differences in food production and water use between current and optimized crop distributions. We find that the current distribution of crops around the world neither attains maximum production nor minimum water use. We identify possible alternative configurations of the agricultural landscape that, by reshaping the global distribution of crops within current rainfed and irrigated croplands based on total water consumption, would feed an additional 825 million people while reducing the consumptive use of rainwater and irrigation water by 14% and 12%, respectively. Such an optimization process does not entail a loss of crop diversity, cropland expansion or impacts on nutrient and feed availability. It also does not necessarily invoke massive investments in modern technology that in many regions would require a switch from smallholder farming to large-scale commercial agriculture with important impacts on rural livelihoods.
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The dwindling groundwater resource of India, supporting almost one fifth of the global population and also the largest groundwater user, has been of great concern in recent years. However, in contrary to the well documented Indian groundwater depletion due to rapid and unmanaged groundwater withdrawal, here for the first time, we report regional-scale groundwater storage (GWS) replenishment through long-term (1996–2014, using more than 19000 observation locations) in situ and decadal (2003–2014) satellite-based groundwater storage measurements in western and southern parts of India. In parts of western and southern India, in situ GWS (GWSobs) has been decreasing at the rate of −5.81 ± 0.38 km³/year (in 1996–2001) and −0.92 ± 0.12 km³/year (in 1996–2002), and reversed to replenish at the rate of 2.04 ± 0.20 km³/year (in 2002–2014) and 0.76 ± 0.08 km³/year (in 2003–2014), respectively. Here, using statistical analyses and simulation results of groundwater management policy change effect on groundwater storage in western and southern India, we show that paradigm shift in Indian groundwater withdrawal and management policies for sustainable water utilization appear to have started replenishing the aquifers in western and southern parts of India.
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Stabilizing greenhouse gas (GHG) emissions from croplands as agricultural demand grows is a critical component of climate change mitigation. Emissions intensity metrics - including carbon dioxide equivalent emissions per kilocalorie produced ('production intensity') - can highlight regions, management practices, and crops as potential foci for mitigation. Yet the spatial and crop-wise distribution of emissions intensity has been uncertain. Here, we develop global crop-specific circa 2000 estimates of GHG emissions and GHG intensity in high spatial detail, reporting the effects of rice paddy management, peatland draining, and nitrogen (N) fertilizer on CH 4, CO 2 and N 2 O emissions. Global mean production intensity is 0.16 Mg CO 2 e M kcal'1, yet certain cropping practices contribute disproportionately to emissions. Peatland drainage (3.7 Mg CO 2 e M kcal'1) - concentrated in Europe and Indonesia - accounts for 32% of these cropland emissions despite peatlands producing just 1.1% of total crop kilocalories. Methane emissions from rice (0.58 Mg CO 2 e M kcal -1), a crucial food staple supplying 15% of total crop kilocalories, contribute 48% of cropland emissions, with outsized production intensity in Vietnam. In contrast, N 2 O emissions from N fertilizer application (0.033 Mg CO 2 e M kcal'1) generate only 20% of cropland emissions. We find that current total GHG emissions are largely unrelated to production intensity across crops and countries. Climate mitigation policies should therefore be directed to locations where crops have both high emissions and high intensities. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
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This study quantifies the green, blue and grey water footprint of global crop production in a spatially-explicit way for the period 1996–2005. The assessment is global and improves upon earlier research by taking a high-resolution approach, estimating the water footprint of 126 crops at a 5 by 5 arc min grid. We have used a grid-based dynamic water balance model to calculate crop water use over time, with a time step of one day. The model takes into account the daily soil water balance and climatic conditions for each grid cell. In addition, the water pollution associated with the use of nitrogen fertilizer in crop production is estimated for each grid cell. The crop evapotranspiration of additional 20 minor crops is calculated with the CROPWAT model. In addition, we have calculated the water footprint of more than two hundred derived crop products, including various flours, beverages, fibres and biofuels. We have used the water footprint assessment framework as in the guideline of the water footprint network. Considering the water footprints of primary crops, we see that global average water footprint per ton of crop increases from sugar crops (roughly 200 m<sup>3</sup> ton<sup>−1</sup>), vegetables (300 m<sup>3</sup> ton<sup>−1</sup>), roots and tubers (400 m<sup>3</sup> ton<sup>−1</sup>), fruits (1000 m<sup>3</sup> ton<sup>−1</sup>), cereals} (1600 m<sup>3</sup> ton<sup>−1</sup>), oil crops (2400 m<sup>3</sup> ton<sup>−1</sup>) to pulses (4000 m<sup>3</sup> ton<sup>−1</sup>). The water footprint varies, however, across different crops per crop category and per production region as well. Besides, if one considers the water footprint per kcal, the picture changes as well. When considered per ton of product, commodities with relatively large water footprints are: coffee, tea, cocoa, tobacco, spices, nuts, rubber and fibres. The analysis of water footprints of different biofuels shows that bio-ethanol has a lower water footprint (in m<sup>3</sup> GJ<sup>−1</sup>) than biodiesel, which supports earlier analyses. The crop used matters significantly as well: the global average water footprint of bio-ethanol based on sugar beet amounts to 51 m<sup>3</sup> GJ<sup>−1</sup>, while this is 121 m<sup>3</sup> GJ<sup>−1</sup> for maize. The global water footprint related to crop production in the period 1996–2005 was 7404 billion cubic meters per year (78% green, 12% blue, 10% grey). A large total water footprint was calculated for wheat (1087 Gm<sup>3</sup> yr<sup>−1</sup>), rice (992 Gm<sup>3</sup> yr<sup>−1</sup>) and maize (770 Gm<sup>3</sup> yr<sup>−1</sup>). Wheat and rice have the largest blue water footprints, together accounting for 45% of the global blue water footprint. At country level, the total water footprint was largest for India (1047 Gm<sup>3</sup> yr<sup>−1</sup>), China (967 Gm<sup>3</sup> yr<sup>−1</sup>) and the USA (826 Gm<sup>3</sup> yr<sup>−1</sup>). A relatively large total blue water footprint as a result of crop production is observed in the Indus River Basin (117 Gm<sup>3</sup> yr<sup>−1</sup>) and the Ganges River Basin (108 Gm<sup>3</sup> yr<sup>−1</sup>). The two basins together account for 25% of the blue water footprint related to global crop production. Globally, rain-fed agriculture has a water footprint of 5173 Gm<sup>3</sup> yr<sup>−1</sup> (91% green, 9% grey); irrigated agriculture has a water footprint of 2230 Gm<sup>3</sup> yr<sup>−1</sup> (48% green, 40% blue, 12% grey).
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India’s continued development depends on the availability of adequate water. This paper applies a data-driven approach to estimate the intra-annual dynamics of water stress across the central Indian Highlands over the period 2002–2012. We investigate the spatial distribution of water demanding sectors including industry, domestic, irrigation, livestock and thermal power generation. We also examine the vulnerability of urban centers within the study area to water stress. We find that 74 % of the area of the central Indian Highlands experienced water stress (defined as demand exceeding supply) for 4 or more months out of the year. The rabi (winter) season irrigation drives the intra-annual water stress across the landscape. The Godavari basin experiences the most surface water stress while the Ganga and Narmada basins experience water stress due to groundwater deficits as a result of rabi irrigation. All urban centers experience water stress at some time during a year. Urban centers in the Godavari basin are considerably water stressed, for example, Achalpur, Nagpur and Chandrapur experience water stress 8 months out of the year. Irrigation dominates water use accounting for 95 % of the total water demand, with substantial increases in irrigated land over the last decade. Managing land use to promote hydrologic functions will become increasingly important as water stress increases.
Pearl millet and sorghum are predominately grown in arid and semi-arid regions of India under rainfed conditions and continue to play a prominent role in the dryland economy in view of limited scope for expansion of irrigated area. Further, these crops possess unique features such as high nutritive value and higher fodder value, and are drought tolerant. The productivity of these crops increased signifi cantly during the green revolution era due to public and private investments in R&D. Though there was productivity enhancement, due to lack of economic incentives and effective demand, farmers reduced the area under millets by shifting to other crops to eke out their livelihood. While sorghum and pearl millet can substantially contribute to food, nutritional and economic security of small and marginal farmers, to stimulate demand for pearl millet and sorghum, value addition at micro and macro levels with technological support and market led extension through food science and nutrition is crucial. The very fact that rabi sorghum has not made inroads despite R&D contributions enhancing productivity, in itself is a prima facie indicator that productivity addresses only the supply side, while consumer demand is crucial, which is possible through value addition and extension efforts incorporating the nutrition and health aspects and meeting the quality requirements of alternative users that are emerging. Farmers have been resistant to switch over to improved varieties in case of rabi sorghum because of fodder quality. Thus, high yielding varieties with fodder quality on par with local races are required to improve the profitability of rabi sorghum.
India has among the highest lost years of life from micronutrient deficiencies. We investigate what dietary shifts would eliminate protein, iron, zinc and Vitamin A deficiencies within households’ food budgets and whether these shifts would be compatible with mitigating climate change. This analysis uses the National Sample Survey (2011–12) of consumption expenditure to calculate calorie, protein and the above micronutrient intake deficiencies and relate them to diets, income and location. We show that more than two-thirds of Indians consume insufficient micronutrients, particularly iron and Vitamin A, and to a lesser extent zinc. A greater proportion of urban households than rural households are deficient at all income levels and for all nutrients, with few exceptions. Deficiencies reduce with increasing income. Using constrained optimization, we find that households could overcome these nutrient deficiencies within their food budgets by diversifying their diets, particularly towards coarse cereals, pulses, and leafy vegetables, and away from rice. These dietary changes could reduce India's agricultural greenhouse gas (GHG) emissions by up to 25%. Current agricultural and food pricing policies may disincentivize these dietary shifts, particularly among the poor.
Demographic growth, changes in diet, and reliance on first-generation biofuels are increasing the human demand for agricultural products, thereby enhancing the human pressure on global freshwater resources. Recent research on the food-water nexus has highlighted how some major agricultural regions of the world lack the water resources required to sustain current growth trends in crop production. To meet the increasing need for agricultural commodities with limited water resources, the water use efficiency of the agricultural sector must be improved. In this regard, recent work indicates that the often overlooked strategy of changing the crop distribution within presently cultivated areas offers promise. Here we investigate the extent to which water in the United States could be saved while improving yields simply by replacing the existing crops with more suitable ones. We propose crop replacement criteria that achieve this goal while preserving crop diversity, economic value, nitrogen fixation, and food protein production. We find that in the United States, these criteria would greatly improve calorie (+46%) and protein (+34%) production and economic value (+208%), with 5% water savings with respect to the present crop distribution. Interestingly, greater water savings could be achieved in water-stressed agricultural regions of the US such as California (56% water savings), and other western states.