Recognizing water stress and critical growth stages in corn and soybeans – Michigan State University

Report on Mitigating Water Stress in Agriculture to Advance Sustainable Development Goals

Introduction: Water Scarcity as a Challenge to SDG 2 (Zero Hunger)

Water is a foundational element for global food security, comprising 80–95% of a plant’s fresh biomass. Water stress represents one of the most significant limiting factors in crop production, adversely affecting grain yield, quality, and nutrient uptake. These impacts directly threaten the achievement of Sustainable Development Goal 2 (Zero Hunger) by jeopardizing stable and nutritious food supplies. Understanding the dynamics of water stress, particularly during critical growth periods, is essential for implementing management decisions that protect agricultural investments and support resilient food systems.

Physiological Impact of Water Scarcity on Crop Production and Resilience

Water stress arises when a plant’s water consumption surpasses the soil’s capacity for water uptake, initiating a series of adaptive mechanisms. While these responses are crucial for survival, they often compromise productivity. Key plant responses include:

• Roots growing deeper to search for moisture.
• Leaves curling or changing orientation to reduce surface area exposed to solar radiation.
• Stomata closure to limit water loss via transpiration, which consequently restricts the gas exchange necessary for photosynthesis and growth.

These defense strategies, which vary by crop type and environmental conditions, are categorized into two main approaches essential for building agricultural resilience:

1. Escape: Accelerating the plant’s life cycle through early flowering and maturity to avoid terminal drought.
2. Avoidance/Tolerance: Conserving water by reducing transpiration, enhancing root system efficacy, or altering leaf orientation.

Early Warning Indicators for Responsible Production (SDG 12)

Early identification of water stress is a cornerstone of responsible production, enabling timely interventions that conserve resources and prevent significant yield loss. Monitoring for physical signs allows for proactive, rather than reactive, management.

• Corn: The primary indicator is leaf rolling. While temporary rolling during midday heat is normal, rolling that begins in the early morning or persists into the evening signals severe water stress. Prolonged stress leads to chlorophyll degradation and potential premature ear decline.
• Soybeans: An early sign is leaf flipping, where leaves expose their silvery-green undersides to reflect sunlight and reduce heat load. As stress intensifies, it can cause flower abortion, premature dropping of lower leaves, and a shortened flowering period.

Vulnerability Assessment During Critical Growth Stages (SDG 2)

The timing of water stress is critical, as its impact on yield is most severe during specific developmental phases. Protecting crops during these windows is paramount for ensuring food security.

• Corn: The most vulnerable period is from tasseling (VT) to the milk stage (R3). Water deficits during this time can lead to pollination failure, kernel abortion, and premature plant death, directly reducing harvestable yield.
• Soybeans: While resilient during vegetative stages, soybeans are highly vulnerable during pod development and seed fill (R3 to R6). Stress during this period causes flower and pod abortion, reduced photosynthetic activity, and smaller seeds, severely diminishing yield potential.

Strategic Interventions for Sustainable Water and Land Management (SDG 6, SDG 12, SDG 13, SDG 15)

Implementing proactive strategies is essential for building resilient agricultural systems that align with multiple Sustainable Development Goals. These practices promote efficient resource use and enhance ecosystem health.

Soil Health and Water Conservation (SDG 15, SDG 6)

• Maintaining high levels of crop residue on the soil surface helps conserve moisture by reducing evaporation, contributing to both sustainable land management (SDG 15) and water security (SDG 6).
• Improving soil structure enhances water infiltration and increases the soil’s water-holding capacity, ensuring water is available in the root zone where it is most needed.

Efficient Water Use and Irrigation Scheduling (SDG 6, SDG 12)

• A key principle of sustainable water management is maintaining adequate soil moisture, generally keeping at least 40–50% of the soil’s available water holding capacity to prevent crop stress.
• Utilizing irrigation scheduling tools and systematically tracking crop water use, weather conditions, and rainfall supports the goals of Responsible Consumption and Production (SDG 12) and Clean Water and Sanitation (SDG 6) by optimizing water application and avoiding waste.

Climate Adaptation and Resilience (SDG 13)

• Applying water at the right time and in the right amount is a critical climate adaptation strategy (SDG 13). This proactive approach mitigates the impacts of drought and extreme heat before they compromise crop health, thereby strengthening the resilience of agricultural systems in the face of climate change.

Analysis of Sustainable Development Goals in the Article

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

• SDG 2: Zero Hunger

  The article directly addresses food production by focusing on “growing high-yielding crops,” protecting “crop investment,” and preventing factors that limit “crop production, affecting grain yield, quality and nutrient uptake.” The entire discussion is centered on ensuring agricultural productivity, which is fundamental to achieving food security.

• SDG 6: Clean Water and Sanitation

  The core theme of the article is water management in agriculture. It discusses “water stress,” “low soil moisture,” efficient “water uptake from the soil,” and strategies to “optimize irrigation water use.” This aligns with the goal of ensuring the availability and sustainable management of water.

• SDG 13: Climate Action

  The article links water stress to climate-related hazards, noting that it “often occurs during the hottest days from July through mid-August.” The discussion of drought defense strategies and building resilience in crops (“escape,” “avoidance/tolerance”) connects to the need to strengthen adaptive capacity to climate-related challenges.

• SDG 15: Life on Land

  The article promotes sustainable land management practices. It suggests methods to “conserve moisture and reduce soil evaporation” by leaving “crop residue on the soil surface” and “improving soil structure.” These actions help combat land degradation and improve the health of terrestrial ecosystems.

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

1. Target 2.4: By 2030, ensure sustainable food production systems and implement resilient agricultural practices that increase productivity and production, that help maintain ecosystems, that strengthen capacity for adaptation to climate change, extreme weather, drought, flooding and other disasters and that progressively improve land and soil quality.

   The article’s advice on managing water stress, improving soil structure, and using crop residue are all examples of “resilient agricultural practices” aimed at increasing productivity (“high-yielding crops”) and adapting to drought conditions.

2. 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 emphasizes the importance of efficient water use through “irrigation scheduling tools,” applying water “at the right time and in the right amount,” and monitoring “crop water use” to “avoid under- or over-watering.” This directly addresses the goal of increasing water-use efficiency in the agricultural sector.

3. Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.

   The article describes how to recognize and manage the impacts of drought and heat (“hottest days”), which are climate-related hazards. The strategies discussed, such as choosing specific crop varieties and implementing timely irrigation, are designed to strengthen the resilience of agricultural systems.

4. Target 15.3: By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world.

   The recommendation to incorporate “practices that leave high amounts of crop residue on the soil surface” and “improving soil structure” are direct methods to restore and improve soil quality, increase water infiltration, and combat the effects of drought on land.

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

• Crop Yield and Quality: The article repeatedly mentions “grain yield,” “high-yielding crops,” and the risk of reduced “yield potential” as outcomes of water stress. This serves as a direct indicator for measuring the success of resilient agricultural practices (Target 2.4).
• Level of Water Stress / Soil Moisture Content: The article provides specific, observable signs of water stress (“leaf rolling,” “leaf flipping,” “flower drop”) and a quantitative guideline to “keep at least 40–50% of your soil’s available water holding capacity.” These can be used as indicators to measure water-use efficiency and the level of water scarcity (Target 6.4).
• Adoption of Sustainable Agricultural Practices: The article suggests specific actions like using “irrigation scheduling tools” and leaving “crop residue on the soil surface.” The rate of adoption of these practices can serve as an indicator for measuring progress towards implementing resilient agriculture and improving land quality (Targets 2.4 and 15.3).

4. Table of SDGs, Targets, and Indicators

Source: canr.msu.edu