Research ArticleAGRICULTURE

Alternative cereals can improve water use and nutrient supply in India

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Science Advances  04 Jul 2018:
Vol. 4, no. 7, eaao1108
DOI: 10.1126/sciadv.aao1108
  • Fig. 1 Time series of consumptive water demand for Indian cereal production.

    Consumption is disaggregated between precipitation on rainfed lands [Green water (R)], precipitation on irrigated lands [Green water (I)], and irrigation water on irrigated lands (Blue water).

  • Fig. 2 District-level changes in total consumptive water demand for cereal production, blue water fraction, and water stress.

    Total consumptive water demand for cereal production is compared for the beginning of the study period [(A) 1966–1970] and the end of the study period [(D) 2005–2009]. (B and 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. “Availability” is the long-term (1970–2000) average of available renewable water, which originates from annual precipitation and contributes to stream flow and groundwater recharge. (C and 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).

  • Fig. 3 Water productivity (m3 H2O) 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, m3 H2O ton−1] 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.

  • Fig. 4 Outcomes of selected rice replacement scenarios.

    Maps show the districts in which rice-harvested areas were replaced by kharif crop with (A and E) the lowest total WFP in each district (scenario 1), (B and F) the lowest blue WFP in each district (scenario 2), (C and G) the highest nutritional yield in terms of protein (metric tons of protein per hectare), and (D and H) the highest nutritional yield in terms of iron (kilograms of iron per hectare). (I) Solid columns correspond to irrigated 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) and green water (green). Because we made no replacements in rainfed rice areas under the replacement scenario based 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.

  • 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.

  • Table 1 National average CWRs weighted by district production.

    CWRs (mm H2O year−1) 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 production. Values in parentheses are the production-weighted SDs. Ellipses indicate that the crop is not produced during a particular season.

    CropKharifRabi
    Green (R)Green (I)Blue (I)Green (R)Green (I)Blue (I)
    Rice641 (160)570 (157)307 (126)263 (47)189 (52)622 (162)
    Wheat321 (57)272 (50)517 (91)
    Maize439 (48)415 (45)49 (47)259 (38)181 (36)237 (46)
    Sorghum425 (59)400 (56)44 (42)220 (72)146 (54)179 (42)
    Finger millet424 (39)400 (30)59 (78)
    Pearl millet314 (129)296 (119)46 (60)

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/7/eaao1108/DC1

    Table S1. CWRs by district (mm H2O year−1) 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 Nutrition’s Indian Food Composition Tables.

    Table S8. List of crop coefficient (kc) 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 H2O year−1) 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.

  • Supplementary Materials

  • The PDF file includes:
    • Legends for tables S1 to S10
    • Fig. S1. Geographic distribution of total CWR (mm H2O year−1) 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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  • Other Supplementary Material for this manuscript includes the following:
    • Table S1 (Microsoft Excel format). CWRs by district (mm H2O year−1) for rainfed and irrigated crops.
    • Table S2 (Microsoft Excel format). National production changes for kharif (monsoon) cereals under replacement scenarios.
    • Table S3 (Microsoft Excel format). Cumulative water savings and changes in nutritional output from replacement scenarios.
    • Table S4 (Microsoft Excel format). Outcomes and descriptions of rice replacement scenarios.
    • Table S5 (Microsoft Excel format). Cereal consumption by crop and by district.
    • Table S6 (Microsoft Excel format). State-level yields of kharif crops and outcomes of rice replacement scenarios.
    • Table S7 (Microsoft Excel format). Crop-specific nutrient content reported in the National Institute of Nutrition’s Indian Food Composition Tables.
    • Table S8 (Microsoft Excel format). List of crop coefficient (kc) values disaggregated by crop, climate zone, and month.
    • Table S9 (Microsoft Excel format). State-level planting dates (month) for each cereal crop and growing season.
    • Table S10 (Microsoft Excel format). Rooting depths for rainfed and irrigated crops as reported by Siebert and Döll (37).

    Download Tables S1 to S10

    Files in this Data Supplement:

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