India is the second-largest cereal exporter globally, making its cereal production vital for both domestic and international food security. Three major states in the Indo-Gangetic Plain (IGP) - Uttar Pradesh, Bihar, and West Bengal - account for 30% of India's total food production and are considered the food bowl of India. The IGP is known for cultivating water-intensive rice and wheat, which together fulfill 63% of the country's calorie demand. However, this system relies heavily on irrigation, with 40% of water sourced from groundwater, further exacerbated by government electricity subsidies that encourage the inefficient use of water and energy.
The overuse of groundwater resources in northern India has led to alarming declines in groundwater levels, with Punjab and Haryana witnessing severe depletion. Surprisingly, even the Ganga Basin, traditionally seen as a water surplus region, has been experiencing significant groundwater depletion in recent years. From 2002 to 2016, the Gangetic basin lost 227 ± 25 km3 of groundwater.
Groundwater depletion due to agricultural intensification is a major threat to water and food security in the Indo-Gangetic Plain (IGP), a critical food bowl, home to 400 million people and currently producing 135 million metric tonnes of cereals.
These declining groundwater levels have led to increased energy consumption for water extraction, raising the cost of cultivation and food prices, thereby impacting food security. Despite these widespread consequences, finding sustainable solutions for this unsustainable groundwater consumption remains a challenge due to the complexity of addressing food and water security, energy savings, farmers' profits, and environmental sustainability simultaneously.
Resolving these issues necessitates considering potentially conflicting objectives across various domains, including water, food, and energy. While global studies have shown promise in optimising crop choices to enhance water and food security, local and regional contexts require specific considerations. In the case of the IGP, studies addressing water, food, and environmental sustainability have been limited.
Recent India-specific research has shown that replacing rice and wheat with less water-intensive crops like millet and sorghum can boost food supply, conserve water and energy, and enhance environmental sustainability. However, these assessments often omit crucial factors, such as farmers' profits. Given the conflicting nature of various sustainability objectives, a multi-objective framework is essential to minimise trade-offs and identify cropping configurations that improve multiple outcomes.
In this study ‘Crop switching for water sustainability in India’s food bowl yields co-benefits for food security and farmers’ profits’, the authors have developed and applied a crop switching optimisation model for cereals in the IGP to maximise calorie production and farmers’ profits and minimise water consumption.
Trends in the use of groundwater, water levels, and net recharge were analysed in the states of Uttar Pradesh, Bihar, and West Bengal, which cover most of the IGP. To address these challenges, the researchers developed a multi-objective optimisation model that considers maximising calorie production, minimising irrigation water, and maximising farmers' profits. This model was applied to all districts in Uttar Pradesh, Bihar, and West Bengal, comparing the results with existing practices. The model aimed to achieve optimal cropping solutions for kharif (rice, maize, sorghum, and millet) and rabi (wheat, sorghum, and barley) cereal crops.
This study primarily focused on cereal crops, which cover 52% of the total crop area and consume 50% of the total water consumption in the IGP. It aimed to reallocate cropped areas between cereals to maximise calorie production and farmers' profits while minimising water consumption at the district level. The study maintained the total cereal cropped area as a constant. Furthermore, the research explored the impacts of yield gap closure and transitioning from flood to drip irrigation to assess potential co-benefits from complementary agricultural interventions.
Discussion
Historical observations and simulations over the Ganga basin showed decreasing trends of rainfall and increasing trends of agricultural water consumption. Both trends together resulted in groundwater depletion in the IGP. However, we could not find any spatially consistent improvements in total calorie production and calorie production per unit water consumption over the districts. The observed well data showed widespread groundwater depletion, specifically over the western side of the region, consistent with the simulated groundwater scenario for 1998–2014.
The crop replacement scenario designed by the proposed multi-objective optimisation approach revealed a widespread replacement of rice with millet and sorghum in the kharif season and of wheat with sorghum in the rabi season.
The optimised crop replacement scenario led to:
- 55% water savings in the kharif season and 9% in the rabi season compared to current practices.
- A 139% increase in profit during the kharif season and a 152% increase in profit during the rabi season.
- An increase in calorie production by 19% in the kharif season and 38% in the rabi season.
- A 46% increase in protein production and a 353% increase in iron production, as well as an 82% increase in zinc production.
- A 41% improvement in net recharge without changing irrigation practices, while changing the irrigation practice alone (shifting from flood to drip irrigation) may improve net recharge by 34%.
Implementing the change in irrigation practice along with the optimised cropping pattern results in a 78% improvement in net recharge. The improvement in energy savings with the proposed crop replacement scenario was computed to be 36% with simultaneous changes in crop and irrigation practices, while implementing them alone may result in 21% and 14% improvement in energy savings, respectively.
If crop switching is carried out on the basis of only one objective of water consumption minimisation, water savings can be increased by 4%. At the same time, there will be a reduction in the improvements in calorie production and profit by 23% and 126%, respectively, compared with the proposed solutions.
Similarly, when the maximisation of profit was considered as the only objective, the entire cropped area will be replaced by the highest profit-making crop, that is, sorghum, as it has the highest MSP and lowest cost of cultivation. This scenario will increase profits by 58% compared with the proposed solution from the multi-objective framework but, simultaneously, reduce calorie production by 18.5% with a marginal increase in water savings of 2%.
The study has also demonstrated the efficacy of our proposed solution for water security by comparison with other proposed alternatives, such as changing from flood to drip irrigation. The framework is easily applicable in different agroclimatic regions.
The suitability of the solution also depends on the demand for alternative cereals. The majority of the population in India, specifically in the IGP, consider rice and wheat to be the major cereals. The policy of switching crops can be successfully implemented only when the mindset of the population in selecting cereals changes, probably systematically with time
In the global market, the demand for nutri cereals is increasing. Also, rice and wheat exports from India are quite small compared with the production of these crops, so selective crop switching towards millets and/or sorghum would likely have little impact on the capacity to export rice or wheat. Hence, there is an opportunity arising for farmers to switch from water-intensive rice and wheat to nutri cereals, leading to water and food sustainability.
Despite the lower cost of cultivation and thus the higher profit from alternative cereals (nutri cereals), farmers currently prefer to cultivate rice and wheat. There might be several factors that need to be considered from the farmers’ perspective, such as the post-harvest processing of cereals, access to agricultural markets, and challenges in converting paddy field to suitable cropland for millets and other nutri cereals.
Way forward
Thus, the implementation of crop switching strategies requires interactions with farmers and consideration of farmers’ input in policy framing. Promoting the cultivation and inclusion of nutri cereals in the PDS, procuring nutri cereals through the MSP and providing incentives to the farmers growing nutri cereals are potential ways to enhance the adoption of these crops by farmers. Subsidised supply of nutri cereals through the PDS may also change (and increase) consumer demand.
However, implementation through the PDS might be difficult considering the political, economic and cultural aspects of a particular region. While such approaches are already being implemented in a few states and are also planned to be implemented as part of the NFSM of the Government of India (GOI) for promoting nutri cereals, such implementation will need to account for the political, economic and cultural differences between regions to better ensure their feasibility and success.
The districts showing the largest potential benefits from implementing optimised cropping patterns could be considered as potential first targets for the procurement of cereals through the PDS system to incentivise farmers. There is scope for future work on policy framing with the proposed solution considering the multiple dimensions of subsidies, irrigation efficiency, yield gap and technological improvements. Also, in our optimisation of cropped areas, we did not put any constraints on the degree of substitution of rice and wheat areas by alternative crops.
Considering this point, the authors ran additional optimisation scenarios for the kharif season in which rice areas were restricted to reductions of 20% and 40%. We found a 17% reduction in the improvement of calorie production in both cases compared with the scenario of putting no constraints on the degree of reduction in rice area. The reductions in water savings were 44% and 32% when the constraints on the degree of reduction in rice area were set as 20% and 40%. Finally, the reductions in the improvements of profit were 123% and 10%, respectively, in both cases.
In conclusion, the challenge of achieving food security for a growing global population while conserving vital resources like water and energy is complex and multifaceted. India, as a major player in global food production, faces a significant role in this endeavour. To address these challenges effectively, a multi-objective approach is crucial, considering the interplay between water, food, energy, farmers' profits, and environmental sustainability, and applying context-specific solutions at local and regional scales.
Cite this paper
Chakraborti, R., Davis, K.F., DeFries, R. et al. Crop switching for water sustainability in India’s food bowl yields co-benefits for food security and farmers’ profits. Nat Water 1, 864–878 (2023). https://doi.org/10.1038/s44221-023-00135-z
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