Energy-efficient strategies for maize-safflower cropping systems: comparative analysis of tillage and weed management practices – Nature

Report on Energy-Efficient Strategies in Maize-Safflower Cropping Systems

A Comparative Analysis in the Context of Sustainable Development Goals

1.0 Introduction: Aligning Agriculture with Global Sustainability Targets

Achieving global food security while ensuring environmental sustainability is a central challenge addressed by the United Nations Sustainable Development Goals (SDGs). This report analyzes a two-year field experiment on a maize-safflower cropping system, evaluating tillage and weed management practices through the lens of key SDGs. The study directly addresses the need for production systems that support SDG 2 (Zero Hunger) by enhancing productivity, while also advancing SDG 12 (Responsible Consumption and Production) and SDG 7 (Affordable and Clean Energy) by optimizing resource and energy use. Furthermore, by examining practices that impact soil health and fossil fuel consumption, the research provides critical insights for SDG 13 (Climate Action) and SDG 15 (Life on Land).

Conventional agricultural practices, characterized by intensive tillage and heavy reliance on chemical inputs, often undermine these goals by contributing to greenhouse gas emissions, soil degradation, and depletion of non-renewable resources. This study investigates sustainable alternatives, focusing on reduced tillage and integrated weed management, to create a framework for agriculture that is productive, profitable, and environmentally sound.

2.0 Experimental Methodology

A two-year field experiment (2018–2020) was conducted in a semi-arid tropical region of India to assess various management practices. The methodology was designed to provide robust data on productivity, economic returns, and energy efficiency, thereby generating evidence for sustainable agricultural intensification.

• Experimental Design: A strip-plot design was used to evaluate treatments in a maize–safflower cropping sequence.
• Tillage Treatments:
  1. Conventional Tillage (CT)
  2. Reduced Tillage (RT)
• Weed Management Treatments: A range of seven practices was evaluated, including a weedy check, manual hand weeding, and various combinations of pre- and post-emergence herbicides, as well as the use of maize residue for mulching.
• Data Analysis: Key metrics were calculated to assess performance against sustainability criteria, including:
  • Crop Yield (Productivity)
  • Cost of Cultivation, Net Returns, and Benefit-Cost Ratio (Profitability)
  • Energy Input, Energy Output, and Energy Use Efficiency (Energetics)

3.0 Key Findings: An Integrated Assessment of Sustainability

3.1 Productivity and Contribution to SDG 2 (Zero Hunger)

Ensuring high productivity is fundamental to achieving food security. The study found that while conventional methods yielded marginally higher outputs, sustainable alternatives were highly competitive.

• Maize Yield: Conventional tillage (CT) produced an 8.68% higher yield (5152 kg ha⁻¹) than reduced tillage (RT) (4705 kg ha⁻¹). Hand weeding at 20 and 40 days after sowing (DAS) resulted in the highest yield (6625 kg ha⁻¹), which was comparable to integrated approaches using herbicides and one instance of hand weeding.
• Safflower Yield: A CT-CT sequence produced the highest seed yield (1389 kg ha⁻¹). Hand weeding again proved most effective (1593 kg ha⁻¹), with a combination of pre-emergence herbicide and maize residue mulching performing similarly (1529 kg ha⁻¹).

These results demonstrate that integrated weed management can maintain high productivity, supporting SDG 2, without complete reliance on either intensive manual labor or purely chemical solutions.

3.2 Economic Viability and Support for SDG 8 (Decent Work and Economic Growth)

Sustainable farming practices must be economically viable to support farmer livelihoods. The analysis revealed important trade-offs between costs, returns, and labor.

• Profitability in Maize: Reduced tillage lowered cultivation costs, but the higher yields from conventional tillage resulted in comparable net returns. This highlights a critical balance needed to ensure economic resilience for farmers. The highest net returns were achieved with hand weeding, though this method also incurred the highest costs. An integrated herbicide strategy (pre-emergence followed by post-emergence) offered the best benefit-cost ratio (3.57), presenting a balanced approach for economic sustainability.
• Profitability in Safflower: Conventional tillage delivered significantly higher net returns (₹47,298 ha⁻¹) and a better benefit-cost ratio, primarily due to higher seed yields.

Optimizing the benefit-cost ratio through integrated management directly contributes to SDG 8 by promoting profitable and sustainable agricultural enterprises.

3.3 Energy Efficiency and Contributions to SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action)

Reducing the energy footprint of agriculture is crucial for mitigating climate change and transitioning to cleaner energy systems. The study identified significant opportunities for energy savings.

1. Primary Energy Consumers: Chemical fertilizers were the most energy-intensive input, accounting for approximately 75.9% of total energy in maize production and 66.3% in safflower. This underscores the need for efficient nutrient management to advance SDG 12.
2. Impact of Tillage: Reduced tillage was superior in energy efficiency. In maize, RT consumed 7.86% less energy than CT, primarily due to lower consumption of diesel fuel. This directly supports SDG 7 by reducing reliance on fossil fuels and contributes to SDG 13 by lowering associated greenhouse gas emissions.
3. Energy Use Efficiency (EUE): In maize, EUE was highest under reduced tillage (9.58%). For safflower, the CT-CT sequence demonstrated the highest EUE (9.21%), indicating that the optimal system may vary by crop.

3.4 Sustainable Production Practices and Support for SDG 12 and SDG 15 (Life on Land)

The management practices evaluated have direct implications for creating sustainable production systems and protecting terrestrial ecosystems.

• Reduced Tillage and Soil Health: By minimizing soil disturbance, reduced tillage helps preserve soil structure, prevent erosion, and maintain soil organic matter, which are essential for combating land degradation as targeted by SDG 15.
• Integrated Weed Management: Combining chemical and non-chemical methods (like hand weeding and mulching) reduces overall herbicide dependency. This approach aligns with SDG 12 by promoting the sound management of chemicals.
• Resource Circularity: The use of maize residue as mulch in safflower cultivation is an excellent example of resource circularity. This practice not only suppresses weeds and conserves soil moisture but also adds organic matter to the soil, enhancing its health and fertility (SDG 15) while making productive use of agricultural by-products (SDG 12).

4.0 Conclusion and Recommendations for Sustainable Intensification

This study confirms that targeted adjustments in tillage and weed management can significantly advance the sustainability of maize-safflower cropping systems, contributing to multiple SDGs simultaneously. Reduced tillage emerges as a key strategy for enhancing energy efficiency (SDG 7) and mitigating climate impact (SDG 13), while integrated weed management offers a pathway to maintain high productivity (SDG 2) and profitability (SDG 8) with reduced chemical reliance (SDG 12).

While conventional tillage showed short-term economic advantages for safflower, the long-term environmental and energy benefits of reduced tillage and integrated management present a more compelling case for sustainable intensification. Future research should focus on the long-term cumulative effects of these practices on soil health, water retention, and biodiversity to provide a holistic framework for resilient and sustainable agriculture that supports both farmers and the planet.

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 tillage and weed management practices in a maize–safflower cropping system addresses several Sustainable Development Goals (SDGs) by focusing on the intersection of agricultural productivity, economic viability, and environmental sustainability. The following SDGs are relevant:

• SDG 2: Zero Hunger: The core of the article is about enhancing food production. It evaluates different agricultural practices to improve the productivity and yield of maize and safflower, which are economically important crops contributing to food security.
• SDG 8: Decent Work and Economic Growth: The study conducts a detailed economic analysis, focusing on the profitability, net returns, and benefit-cost ratio of various farming practices. This relates to ensuring the economic viability of farming and promoting productive employment in the agricultural sector.
• SDG 12: Responsible Consumption and Production: This is a central theme. The article analyzes the energy efficiency of different agricultural practices, aiming to optimize the use of resources like fossil fuels (diesel), chemical fertilizers, and herbicides. It seeks to identify more sustainable production patterns that minimize resource depletion and environmental impact.
• SDG 13: Climate Action: The introduction explicitly links conventional agricultural practices, particularly the heavy use of fossil fuels for tillage, to greenhouse gas emissions. By evaluating energy-efficient strategies like reduced tillage, the study contributes to climate change mitigation efforts in agriculture.
• SDG 15: Life on Land: The article highlights the negative impacts of intensive tillage on soil health, such as “soil erosion, degradation of soil structure, and a decline in soil organic matter (SOM).” The evaluation of reduced tillage as an alternative directly addresses the goal of halting and reversing land degradation and promoting sustainable use of terrestrial ecosystems.

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

Based on the article’s focus, several specific SDG targets can be identified:

1. Target 2.4: “By 2030, ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production… and that progressively improve land and soil quality.”
   • Explanation: The entire experiment is designed to identify sustainable agricultural practices. It compares conventional tillage (CT) with reduced tillage (RT) and various weed management methods to find a balance between increasing crop yields (productivity) and maintaining environmental health (e.g., preserving soil structure and reducing energy consumption).
2. Target 8.4: “Improve progressively, through 2030, global resource efficiency in consumption and production…”
   • Explanation: The “Energy balance studies” section is a direct analysis of resource efficiency. The study calculates “Energy use efficiency,” “Energy productivity,” and “Energy intensity” to determine how efficiently inputs like fuel, fertilizer, and labor are converted into agricultural output. For example, it notes that reduced tillage has a higher energy use efficiency in maize (9.58%).
3. Target 12.2: “By 2030, achieve the sustainable management and efficient use of natural resources.”
   • Explanation: The research evaluates how to use natural resources more efficiently. It finds that “reduced tillage resulted in lower cultivation costs” due to less use of “machinery, labour, and fuel.” The detailed breakdown of energy inputs from diesel, fertilizers, and machinery directly addresses the management and use of these resources.
4. Target 15.3: “By 2030, combat desertification, restore degraded land and soil… and strive to achieve a land degradation-neutral world.”
   • Explanation: The introduction states that “intensive tillage practices can lead to soil erosion, degradation of soil structure, and a decline in soil organic matter (SOM).” The study’s comparison of conventional tillage with reduced tillage is an investigation into practices that can mitigate these forms of land and soil degradation.

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 and qualitative indicators that can be used to measure progress towards the identified targets:

• Indicators for Agricultural Productivity and Profitability (Target 2.4):
  • Crop Yield: The article measures maize grain yield and safflower seed yield in kg ha⁻¹. For instance, it reports that conventional tillage in maize produced a yield of “5152 kg ha⁻¹”.
  • Net Returns: Profitability is measured in terms of Net Returns (NR) in ₹ ha⁻¹. The study found the highest net returns for maize (₹82,089 ha⁻¹) were achieved with hand weeding.
  • Benefit-Cost Ratio (BCR): This is used to evaluate “the techno-economic feasibility of the treatments.” A high BCR of 3.57 was noted for a specific herbicide combination in maize.
• Indicators for Resource Efficiency (Targets 8.4 and 12.2):
  • Energy Use Efficiency (%): This is explicitly calculated as the ratio of energy output to input. The article states that energy use efficiency was “superior under RT in maize (9.58%)”.
  • Energy Input (MJ ha⁻¹): The study quantifies the total energy consumed by different practices, noting that conventional tillage in maize required a higher input (“17,302 MJ ha⁻¹”) compared to reduced tillage (“15,942 MJ ha⁻¹”).
  • Energy Productivity (kg MJ⁻¹): This measures the amount of crop yield produced per unit of energy input.
• Indicators for Soil and Land Health (Target 15.3):
  • Soil Organic Matter (SOM) / Organic Carbon: The introduction identifies the decline in SOM as a key problem of intensive tillage. The methods section provides a baseline indicator of the soil’s “moderate organic carbon content (0.37%).” While not tracked over time in the results, it is the implied variable that sustainable practices like reduced tillage aim to protect.
  • Soil Bulk Density: The article mentions the initial soil bulk density (“1.42 g cm⁻³”) as a characteristic of the experimental site’s soil health. Tillage practices directly affect this indicator over time.

4. Table of SDGs, Targets, and Indicators

Source: nature.com