Response of continuous cropping cowpea and root-zone soil to composite microbial agents: plant growth promotion and nitrogen-fixing bacterial community regulation – BMC Plant Biology

Report on Sustainable Agricultural Practices and Soil Microbiome Management in Alignment with Sustainable Development Goals

Introduction: Advancing Sustainable Agriculture for Global Goals

Achieving the Sustainable Development Goals (SDGs), particularly SDG 2 (Zero Hunger) and SDG 15 (Life on Land), requires a fundamental shift in agricultural practices. Current research highlights the critical role of soil health and microbial ecosystems in developing resilient and productive agri-food systems. This report synthesizes recent scientific findings on the impacts of conventional farming methods and the potential of microbial-based solutions to foster sustainable agriculture. The focus is on mitigating the negative effects of continuous cropping, enhancing soil fertility through biological means, and leveraging the benefits of leguminous crops to ensure food security and protect terrestrial ecosystems.

The Impact of Continuous Cropping on Soil Health and SDG Alignment

Continuous cropping, or monoculture, presents a significant obstacle to sustainable agriculture by degrading soil health, which directly undermines SDG 15 (Life on Land). This practice often leads to a decline in soil fertility and an imbalance in microbial communities, threatening long-term crop productivity and thus impacting SDG 2 (Zero Hunger).

Key Research Findings:

• Studies by Ahsan et al. (2024), Xia et al. (2025), and Gong et al. (2024) demonstrate that continuous cropping systems for crops like peanuts and tobacco alter soil microbial community structure, reduce diversity, and degrade soil physicochemical properties.
• Chen et al. (2022) and Ding et al. (2024) provide further evidence that these systems disrupt essential nutrient cycles and can lead to the accumulation of soilborne pathogens, creating a negative feedback loop that reduces crop yields.
• Addressing these challenges is essential for halting land degradation (SDG 15.3) and building sustainable food production systems (SDG 2.4).

Microbial Inoculants: A Tool for Sustainable Intensification and Responsible Production (SDG 12)

Microbial inoculants and biofertilizers offer a promising pathway to enhance agricultural sustainability, aligning with SDG 12 (Responsible Consumption and Production) by reducing reliance on synthetic chemical inputs. These biological agents improve soil health, promote plant growth, and can help restore ecological balance in agricultural lands.

Enhancing Soil Fertility and Nutrient Cycling

Improving nutrient availability through biological processes is fundamental to achieving Zero Hunger (SDG 2). Microbial agents play a central role in this effort.

1. Nitrogen Fixation: Legumes and nitrogen-fixing bacteria, such as Azotobacter and Bradyrhizobium, are crucial for biological nitrogen fixation, a natural process that converts atmospheric nitrogen into a form usable by plants. Research by Kebede (2021) and Aasfar et al. (2021) underscores the importance of this process for reducing the need for synthetic nitrogen fertilizers, whose production contributes to greenhouse gas emissions.
2. Nutrient Solubilization: Bacteria such as Enterobacter ludwigii and various Bacillus species can solubilize essential nutrients like potassium and phosphorus, making them available for plant uptake. Studies by Raji & Thangavelu (2021) and Gao et al. (2025) confirm that these microbes significantly boost nutrient acquisition and plant growth.
3. Improved Soil Structure: As highlighted by Liu et al. (2021) and Du et al. (2022), the long-term application of organic and microbial fertilizers improves soil properties, regulates soil bacteria, and ultimately increases crop yields, contributing directly to SDG 2.

Biological Control for Ecosystem Health (SDG 15)

The use of microbial agents for biological control of plant pathogens is a key strategy for protecting biodiversity and reducing chemical pollution, supporting SDG 15 (Life on Land) and SDG 12 (Responsible Production).

• Villavicencio-Vásquez et al. (2025) review the mechanisms of biological control agents, which can suppress soilborne pathogens without the adverse environmental effects of chemical pesticides.
• Microbes like Trichoderma harzianum and Bacillus subtilis are effective biocontrol agents. Research by Xiao et al. (2023) and Chohan et al. (2024) demonstrates their capacity to control diseases like Fusarium wilt, thereby protecting crops and soil ecosystems.
• By integrating these agents, farming systems can reduce their chemical footprint, preserving the biodiversity of soil life.

The Role of Legumes in Sustainable Agri-Food Systems (SDG 2 & SDG 15)

Legumes, such as cowpea (Vigna unguiculata L. Walp), are integral to building sustainable food systems that advance multiple SDGs. They provide nutritious food, improve soil health, and enhance agricultural biodiversity.

Contributions to Nutrition and Soil Health:

• Nutritional Security (SDG 2): Cowpea is a multipurpose crop rich in protein and micronutrients, offering a solution to malnutrition. Its nutritional advantages are well-documented by Gonçalves et al. (2016) and Jayathilake et al. (2018).
• Soil Enrichment (SDG 15): As legumes, cowpeas form symbiotic relationships with nitrogen-fixing bacteria (Yeremko et al., 2025), enriching the soil and reducing the need for external fertilizers. This natural fertilization process helps restore degraded land and supports subsequent crops in rotation systems, as explored by Carrascosa-Robles et al. (2024).
• Environmental Sustainability: Omomowo & Babalola (2021) highlight the prospects of improving cowpea productivity to ensure both food security and environmental sustainability, making it a cornerstone crop for achieving the SDGs.

Conclusion: Integrating Microbial Solutions for a Sustainable Future

The body of research indicates a clear path toward more sustainable agriculture through the strategic management of soil microbiomes. By moving away from degradative practices like continuous cropping and embracing microbial inoculants, biofertilizers, and crop diversification with legumes, agriculture can become a solution for achieving the Sustainable Development Goals. These nature-based approaches enhance soil fertility, protect biodiversity, and build resilient food systems capable of meeting the challenges of Zero Hunger (SDG 2), Responsible Production (SDG 12), and protecting Life on Land (SDG 15). Future efforts must focus on optimizing the formulation and application of these technologies to maximize their global impact.

Analysis of Sustainable Development Goals (SDGs)

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

The article, which consists of a list of scientific references, primarily addresses issues related to sustainable agriculture, food security, and environmental health. Based on the titles of the cited papers, the following SDGs are relevant:

• SDG 2: Zero Hunger: Many references focus on improving crop productivity, nutritional security, and developing sustainable agri-food systems. For example, reference 10 explicitly mentions “improving cowpea productivity to ensure food, nutritional security,” and other papers discuss enhancing the yield of crops like peanuts (Ref 17), rice (Ref 54), and maize (Ref 33).
• SDG 12: Responsible Consumption and Production: The emphasis on using “biocontrol agents” (Ref 18, 32, 60, 62) and “microbial inoculants” (Ref 20, 31, 55) as alternatives to chemical fertilizers and pesticides aligns with the goal of achieving environmentally sound management of chemicals. Reference 11, which discusses “pesticide residues in cowpea,” highlights the problem that these biological alternatives aim to solve.
• SDG 15: Life on Land: The core theme of the references is the health of terrestrial ecosystems, specifically agricultural soils. Numerous titles refer to “soil microbial community structure and diversity” (Ref 1, 3, 5), “soil fertility” (Ref 2, 58), and mitigating the negative effects of “continuous cropping” (Ref 1, 31, 44, 63, 64), which directly relates to halting and reversing land degradation and biodiversity loss within soil ecosystems.

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

Several specific SDG targets can be linked to the research topics presented in the article’s references:

• Under SDG 2 (Zero Hunger):
  • Target 2.4: “By 2030, ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production, that help maintain ecosystems… and that progressively improve land and soil quality.” This target is central to the article. The research on microbial fertilizers (Ref 1), crop rotation (Ref 13), biological nitrogen fixation (Ref 14), and the use of microbial inoculants to improve soil health (Ref 32, 54, 57) are all examples of implementing resilient and sustainable agricultural practices.
• Under SDG 12 (Responsible Consumption and Production):
  • Target 12.4: “By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle… and significantly reduce their release to air, water and soil in order to minimize their adverse impacts on human health and the environment.” The focus on “biocontrol agents” (Ref 18, 19, 34, 60) and “biofertilizers” (Ref 36, 57) as substitutes for synthetic chemical inputs directly supports this target by promoting alternatives that reduce chemical release into the soil.
• Under SDG 15 (Life on Land):
  • Target 15.3: “By 2030, combat desertification, restore degraded land and soil… and strive to achieve a land degradation-neutral world.” The research aimed at mitigating “continuous cropping obstacles” (Ref 31, 63, 64) and improving the fertility of “reclaimed soil in a coal mining area” (Ref 58) are direct efforts to restore degraded agricultural land and improve soil quality.
  • Target 15.5: “Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity…” The extensive focus on understanding and enhancing “soil microbial community structure and diversity” (Ref 1, 24, 30, 34, 41, 45) is a key component of halting biodiversity loss within the critical soil ecosystem.

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

The article does not explicitly mention official SDG indicators. However, the research topics imply several measurable parameters that can serve as indicators of progress:

• For Target 2.4 (Sustainable Food Production):
  • Crop Yield and Growth: Progress can be measured by changes in crop productivity. References mention “peanut growth and yield” (Ref 17), “walnut yield” (Ref 57), and “rice yield” (Ref 54) as key outcomes of applying sustainable practices.
  • Soil Health Metrics: The improvement in soil quality is a direct measure. This is implied by the analysis of “soil physicochemical properties” (Ref 3, 5), “soil fertility” (Ref 2, 58), and “soil organic carbon” (Ref 56).
• For Target 12.4 (Chemical Management):
  • Adoption of Biological Alternatives: The extent to which “biocontrol agents” (Ref 18, 62) and “microbial inoculants” (Ref 20, 55) are used in place of chemical fertilizers and pesticides would be a primary indicator.
  • Reduction in Chemical Residues: A direct measure of success would be the reduction of “pesticide residues” in food products like cowpea, as investigated in reference 11.
• For Target 15.3 (Land Degradation):
  • Soil Nutrient Cycling: The efficiency of nutrient cycles is a key indicator of soil health. This is implied by studies on “biological nitrogen fixation” (Ref 14, 56), “potassium solubilizing bacteria” (Ref 39, 40), and overall “nutrient cycles” (Ref 64).
• For Target 15.5 (Biodiversity Loss):
  • Soil Microbial Diversity: The diversity and composition of the soil microbiome serve as a direct indicator of soil biodiversity. Many references focus on measuring the “biodiversity of denitrifying and dinitrogen-fixing bacteria” (Ref 24) and the overall “soil microbial diversity” (Ref 34, 41, 43) in response to different agricultural practices.

4. Summary Table of SDGs, Targets, and Indicators

Source: bmcplantbiol.biomedcentral.com