Yield and water productivity of rice as influenced by crop establishment and irrigation methods under temperate environment – Nature

 

Executive Summary Report on Sustainable Rice Cultivation Methods

This report analyzes a comparative study on rice cultivation, evaluating direct-seeded rice (DSR) against traditional transplanted rice (TPR) under three irrigation regimes: conventional flooding (CF), saturation (SA), and alternate wetting and drying (AWD). The findings strongly indicate that DSR, particularly when combined with water-saving irrigation techniques, offers a superior pathway to achieving multiple Sustainable Development Goals (SDGs). DSR demonstrated significantly higher grain yields (6.69–7.8 t ha⁻¹ vs. 5.59–6.18 t ha⁻¹ for TPR), directly contributing to SDG 2 (Zero Hunger). Furthermore, DSR improved water productivity by 11–25% and, when combined with SA or AWD methods, reduced total water input by up to 25%, addressing SDG 6 (Clean Water and Sanitation). From an economic perspective, DSR yielded a benefit-cost ratio of 2.2 compared to 1.48 for TPR, promoting SDG 8 (Decent Work and Economic Growth) by enhancing farmer profitability. The method’s increased resource efficiency and shorter crop cycle also align with SDG 12 (Responsible Consumption and Production) and SDG 13 (Climate Action). The study concludes that the adoption of DSR with SA or AWD irrigation is a viable, multi-faceted strategy for sustainable and resilient rice production in temperate climates.

1.0 Introduction: Aligning Rice Cultivation with Sustainable Development Goals

Rice is a staple food for over half the global population, making its sustainable production critical to global food security. However, conventional rice farming, characterized by transplanting seedlings into puddled, flooded fields, faces significant sustainability challenges that conflict with several SDGs. These challenges include:

• High Water Consumption: Traditional methods are water-intensive, consuming 3,000-5,000 liters of water per kilogram of rice, placing immense pressure on dwindling freshwater resources and hindering progress towards SDG 6 (Clean Water and Sanitation).
• Labor Intensity and Cost: Transplanting is labor-intensive and increasingly expensive, impacting the economic viability for smallholder farmers and conflicting with the objectives of SDG 8 (Decent Work and Economic Growth).
• Greenhouse Gas Emissions: Continuous flooding of paddies creates anaerobic conditions that lead to significant methane emissions, a potent greenhouse gas, thereby working against SDG 13 (Climate Action).

This report details the findings of a study designed to evaluate more sustainable alternatives. By comparing direct-seeded rice (DSR) with transplanted rice (TPR) and assessing water-saving irrigation methods (saturation and AWD), this research provides evidence-based solutions to align rice cultivation with the principles of SDG 12 (Responsible Consumption and Production) and enhance food security as outlined in SDG 2 (Zero Hunger).

2.0 Methodology: Evaluating Sustainable Rice Production Systems

The study was conducted over two years in a temperate environment to assess two primary factors impacting rice sustainability: crop establishment method and irrigation technique.

1. Establishment Methods:
   • Direct-Seeded Rice (DSR): Seeds were sown directly into the main field.
   • Transplanted Rice (TPR): Seedlings were raised in a nursery and transplanted into puddled fields, representing the conventional method.
2. Irrigation Methods:
   • Conventional Flooding (CF): Continuous flooding of fields, serving as the control.
   • Saturation (SA): Soil was kept saturated without standing water.
   • Alternate Wetting and Drying (AWD): Fields were irrigated and then allowed to dry to a specific level before re-irrigation.

Key performance indicators were measured, including crop growth parameters, yield, water input, water productivity, and economic returns (benefit-cost ratio), to provide a comprehensive assessment of each system’s contribution to sustainable development.

3.0 Results: A Comparative Analysis of Cultivation and Irrigation Methods

3.1 Agronomic Performance and Yield: Advancing SDG 2 (Zero Hunger)

The DSR method demonstrated superior agronomic performance, leading to higher yields and thereby contributing directly to food security targets.

• Yield Components: DSR produced a greater number of tillers (635–650 m⁻²) and panicles (510–529 m⁻²) compared to TPR.
• Grain Yield: DSR achieved a grain yield of 6.69 to 7.8 t ha⁻¹, significantly outperforming TPR, which yielded between 5.59 and 6.18 t ha⁻¹. This represents an 8-21% yield advantage for DSR.
• Spikelet Sterility: DSR exhibited lower spikelet sterility (9.9–10.8%), indicating more efficient grain formation.

These results show that shifting to DSR can increase food production from the same land area, a key objective of SDG 2.

3.2 Water Productivity and Conservation: Meeting SDG 6 (Clean Water and Sanitation)

The study highlights significant gains in water efficiency, a critical component of sustainable water management.

• Establishment Method Impact: DSR demonstrated 11–25% higher water productivity (kg of grain per m³ of water) than TPR.
• Irrigation Method Impact: The SA and AWD methods proved far more efficient than CF.
  1. Water productivity under CF was 28% lower than under the SA method.
  2. Water productivity under CF was 25% lower than under the AWD method.

By producing more crops with less water, the combination of DSR with SA or AWD irrigation directly supports the water-use efficiency targets of SDG 6.

3.3 Economic Viability: Promoting SDG 8 (Decent Work and Economic Growth)

The economic analysis revealed that DSR is a more profitable method for farmers, enhancing livelihoods and promoting economic growth.

• Cost of Cultivation: DSR eliminates the significant labor and resource costs associated with nursery raising, puddling, and transplanting.
• Benefit-Cost Ratio (B:C): DSR delivered a superior return on investment, with a B:C ratio of 2.2 (a profit of ₹2.2 per rupee invested). In contrast, the B:C ratio for TPR was only 1.48.

This enhanced profitability makes rice farming more economically sustainable for farmers, aligning with the goals of SDG 8.

3.4 Resource Efficiency and Climate Adaptation: Supporting SDG 12 and SDG 13

The DSR method demonstrated greater overall resource efficiency and adaptive capacity, which is crucial for responsible production and climate action.

• Shorter Crop Duration: DSR crops reached maturity 10 days earlier than TPR crops. This reduces the crop’s exposure to end-of-season climate risks and allows for more flexible cropping schedules, contributing to climate adaptation (SDG 13).
• Higher Heat Use Efficiency (HUE): DSR was more efficient at converting thermal energy into biomass, achieving higher yields in a shorter period.
• Reduced Methane Emissions: While not directly measured, the use of SA and AWD irrigation methods reduces the duration of anaerobic soil conditions typical of CF, which is known to substantially lower methane emissions, thus contributing to climate change mitigation (SDG 13).

These efficiencies signify a shift towards more sustainable production patterns as envisioned by SDG 12.

4.0 Conclusion and Recommendations for Sustainable Rice Farming

The study provides compelling evidence that direct-seeded rice (DSR) is a more productive, profitable, and resource-efficient alternative to traditional transplanted rice. The practice of conventional flooding is demonstrably wasteful, whereas both saturation (SA) and alternate wetting and drying (AWD) irrigation methods can sustain high yields while drastically improving water productivity.

Based on these findings, the following recommendations are made to advance sustainable rice cultivation:

1. Promote Adoption of DSR: Policymakers and extension services should actively promote the adoption of DSR to enhance food security (SDG 2), improve farmer incomes (SDG 8), and build climate resilience (SDG 13).
2. Transition to Water-Saving Irrigation: A shift away from conventional flooding towards SA or AWD irrigation is critical for sustainable water management (SDG 6) and reducing the climate footprint of rice farming (SDG 13).
3. Integrate Best Practices: The greatest sustainability gains are achieved by combining DSR with either SA or AWD irrigation. This integrated approach represents a best practice for achieving responsible production and consumption (SDG 12) in rice agriculture.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article on rice cultivation methods addresses several Sustainable Development Goals (SDGs) by focusing on agricultural productivity, water conservation, economic viability, and climate change mitigation. The following SDGs are relevant:

• SDG 2: Zero Hunger: The study directly addresses food security by evaluating methods to increase the yield of rice, a staple food for more than half of the global population.
• SDG 6: Clean Water and Sanitation: A primary focus of the article is on water usage in agriculture, comparing different irrigation methods to improve water productivity and address the challenge of receding water resources.
• SDG 8: Decent Work and Economic Growth: The article analyzes the economic efficiency of different cultivation methods, highlighting their profitability and impact on farmers’ livelihoods. It also touches upon the issue of a decreasing agricultural workforce.
• SDG 12: Responsible Consumption and Production: The research promotes sustainable agricultural practices that ensure the efficient use of natural resources, particularly water, to produce more food with less environmental impact.
• SDG 13: Climate Action: The article implicitly connects to climate action by discussing how alternative irrigation methods can reduce the use of conventional flooding, a practice known to produce methane, a potent greenhouse gas.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the article’s content, the following specific SDG targets can be identified:

1. SDG 2: Zero Hunger

   • Target 2.3: By 2030, double the agricultural productivity and incomes of small-scale food producers. The article supports this by demonstrating that Direct-Seeded Rice (DSR) can significantly increase grain yield (“6.69 to 7.8 t ha⁻¹ for DSR, surpassing that of transplanted rice, which yielded between 5.59 and 6.18 t ha⁻¹”) and economic returns (“profit per rupee invested of 2.2, compared to 1.48 for transplanted rice”).
   • Target 2.4: By 2030, ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production, that help maintain ecosystems… The study promotes DSR with alternate wetting and drying (AWD) or saturation methods as a “more sustainable and efficient alternative to transplanted rice cultivation” that saves water and potentially reduces greenhouse gas emissions.

2. SDG 6: Clean Water and Sanitation

   • Target 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity. The article’s core finding is that DSR enhances water efficiency. It states that “DSR demonstrated 11–25% higher water productivity” and that AWD and saturation methods led to “a 28% reduction in water productivity compared to the saturation method and a 25% reduction compared to the alternate wetting and drying method” over conventional flooding.

3. SDG 8: Decent Work and Economic Growth

   • Target 8.2: Achieve higher levels of economic productivity through diversification, technological upgrading and innovation. The study presents DSR as a technological innovation that improves economic productivity. The economic analysis shows a higher benefit-cost ratio for DSR, indicating its economic superiority and contribution to more profitable farming.

4. SDG 12: Responsible Consumption and Production

   • Target 12.2: By 2030, achieve the sustainable management and efficient use of natural resources. The research directly addresses this target by showing how DSR and improved irrigation techniques can significantly reduce the consumption of water, a critical natural resource, in rice production. The article notes that DSR “not only saves water and labour but also reduces the risk of climate change.”

5. SDG 13: Climate Action

   • Target 13.2: Integrate climate change measures into national policies, strategies and planning. The article provides a scientific basis for adopting agricultural practices that mitigate climate change. It mentions that “rice farming with conventional flood irrigation produces methane which is considered a potential greenhouse gas.” By promoting methods that reduce or eliminate flooding, the study contributes to climate change mitigation strategies in agriculture.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article provides several quantitative indicators that can be used to measure progress towards the identified targets:

1. Indicators for SDG 2 (Zero Hunger)

   • Grain Yield (t ha⁻¹): The article provides specific yield data: “Grain yield ranged from 6.69 to 7.8 t ha⁻¹ for DSR, surpassing that of transplanted rice, which yielded between 5.59 and 6.18 t ha⁻¹.” This directly measures agricultural productivity (Target 2.3).
   • Spikelet Sterility (%): Lower sterility indicates better crop health and potential yield. The study notes “lower spikelet sterility (9.9–10.8%)” for DSR, which is a factor in its higher yield.

2. Indicators for SDG 6 (Clean Water and Sanitation)

   • Water Productivity (kg m⁻³): This is a direct measure of water-use efficiency (Target 6.4). The article states, “DSR recorded significantly higher WP (0.38 & 0.42 kg m⁻³) as compared to transplanted rice (0.31 & 0.38 kg m⁻³).”
   • Percentage of Water Saving (%): The study quantifies water savings from different irrigation methods: “Actual water saving… was 23–24.5% and 24.6 to 25.3% in saturation and AWD over CF.”
   • Total Water Input (mm): This measures the volume of water consumed. The article notes that the combination of transplanting and conventional flooding consumed a “significantly higher volume (2011–2225 mm) of water.”

3. Indicators for SDG 8 (Decent Work and Economic Growth)

   • Benefit-Cost Ratio (B:C): This indicator measures economic productivity and profitability (Target 8.2). The article finds a “profit per rupee invested of 2.2” for DSR, compared to “1.48 for transplanted rice.”

4. Indicators for SDG 12 (Responsible Consumption and Production)

   • Water Productivity (kg m⁻³) and Water Saving (%): These indicators from SDG 6 also serve to measure the efficient use of natural resources under Target 12.2.

5. Indicators for SDG 13 (Climate Action)

   • Reduction in Conventional Flooding: While not a direct measure of emissions, the shift away from conventional flooding towards methods like AWD is an implied indicator of progress. The study’s conclusion that AWD can produce comparable yields while “significantly reducing water usage” supports this shift, thereby mitigating methane emissions.

4. Table of SDGs, Targets, and Indicators

SDGs	Targets	Indicators
SDG 2: Zero Hunger	2.3: Double agricultural productivity and incomes. 2.4: Ensure sustainable food production systems.	Grain Yield (t ha⁻¹): 6.69-7.8 for DSR vs. 5.59-6.18 for transplanted. Spikelet Sterility (%): 9.9-10.8% for DSR.
SDG 6: Clean Water and Sanitation	6.4: Substantially increase water-use efficiency.	Water Productivity (kg m⁻³): 0.38-0.42 for DSR vs. 0.31-0.38 for transplanted. Percentage increase in Water Productivity: 11-25% higher in DSR. Water Saving (%): 23-25% in saturation and AWD methods over conventional flooding.
SDG 8: Decent Work and Economic Growth	8.2: Achieve higher levels of economic productivity through technological upgrading.	Benefit-Cost Ratio (B:C): 2.2 for DSR vs. 1.48 for transplanted rice.
SDG 12: Responsible Consumption and Production	12.2: Achieve sustainable management and efficient use of natural resources.	Total Water Input (mm): Reduced water use in DSR and AWD/saturation methods. Labor Saving (Implied): DSR avoids nursery raising and transplanting, reducing labor input.
SDG 13: Climate Action	13.2: Integrate climate change measures into policies and planning.	Reduced use of conventional flood irrigation (Implied indicator for methane reduction).

Source: nature.com