Water is a vital resource for agriculture, but it is also becoming increasingly scarce and variable due to climate change, population growth, and competing demands from other sectors. Agriculture accounts for about 70% of global freshwater withdrawals, and up to 90% in some developing countries (FAO, 2017). At the same time, agriculture is also a major contributor to water pollution, through sediment, nutrient, and pesticide runoff from fields and livestock operations. To ensure the long-term sustainability and resilience of agricultural systems, farmers and land managers need to adopt water conservation and management practices that optimize water use efficiency, reduce water losses and degradation, and enhance water quality and ecosystem services.
Principles of Water Conservation and Management
Water conservation and management in agriculture should be guided by the following principles:
- Efficiency: Optimize water use efficiency by minimizing water losses and maximizing crop water productivity, through practices such as irrigation scheduling, precision irrigation, and crop selection and breeding.
- Sufficiency: Provide adequate water to meet crop water requirements and maintain soil moisture, while avoiding overuse or underuse of water resources.
- Sustainability: Manage water resources in a way that maintains or enhances their long-term availability and quality, and supports the health and function of aquatic and terrestrial ecosystems.
- Resilience: Build the capacity of agricultural systems to adapt to and recover from water-related shocks and stresses, such as droughts, floods, and water quality degradation, through practices such as water storage, diversification, and risk management.
- Equity: Ensure fair and equitable access to and allocation of water resources among different users and sectors, and protect the water rights and needs of vulnerable and marginalized groups, such as smallholder farmers and indigenous communities.
By following these principles, farmers and land managers can develop and implement water conservation and management strategies that are context-specific, adaptive, and integrative, and that balance the multiple objectives of food production, water security, environmental stewardship, and social justice.
Practices for Water Conservation and Management
There are many specific practices that farmers and land managers can use to implement the principles of water conservation and management, depending on their local context and goals. Here are some of the most common and effective practices:
Irrigation Scheduling and Precision Irrigation
Irrigation scheduling is the practice of applying the right amount of water at the right time to meet crop water requirements and maintain soil moisture, based on factors such as crop type, growth stage, soil type, and weather conditions.
Precision irrigation is the use of advanced technologies and data to optimize irrigation scheduling and application, such as:
- Soil moisture sensors: Use sensors to monitor soil moisture levels in real-time and trigger irrigation when needed, to avoid over- or under-watering.
- Evapotranspiration (ET) models: Use models that estimate crop water use based on weather data, crop coefficients, and other parameters, to determine irrigation timing and amount.
- Variable rate irrigation: Use systems that can apply different amounts of water to different parts of a field, based on soil type, topography, and other spatial variability, to optimize water use efficiency and uniformity.
- Drip irrigation: Use systems that deliver water directly to the crop root zone through a network of pipes, emitters, and drippers, to minimize water losses from evaporation, runoff, and deep percolation.
By using these technologies and practices, farmers can reduce water use by 20-50% compared to traditional irrigation methods, while maintaining or increasing crop yields and quality (Gellings, 2015).
Soil Health Management
Soil health management is the use of practices that improve soil's physical, chemical, and biological properties, such as soil structure, organic matter, nutrient cycling, and water-holding capacity. Healthy soils can absorb and retain more water, reduce runoff and erosion, and support plant growth and resilience under water stress.
Some key soil health management practices for water conservation include:
- Conservation tillage: Use practices that minimize soil disturbance, such as no-till, strip-till, or reduced-till, to maintain crop residues on the soil surface, increase soil organic matter, and improve soil structure and infiltration.
- Cover cropping: Use plants that are grown primarily to protect and improve the soil, such as legumes, grasses, and brassicas, to provide living roots, add biomass, fix nitrogen, and suppress weeds, pests, and diseases.
- Crop rotation: Use diverse crop rotations that alternate between different plant families and rooting depths, to break pest and disease cycles, balance nutrient demands, and improve soil health and function.
- Organic amendments: Use organic materials, such as compost, manure, and biochar, to add organic matter, nutrients, and beneficial microbes to the soil, and enhance soil water holding capacity and infiltration.
By using these practices, farmers can increase soil water storage by 10-20%, reduce irrigation water use by 25-50%, and improve crop yields and resilience under drought stress (Basche & DeLonge, 2019).
Water Harvesting and Storage
Water harvesting and storage is the practice of collecting and storing water from various sources, such as rainfall, runoff, and groundwater, for later use in irrigation, livestock watering, and other agricultural activities. Water harvesting and storage can help buffer against water scarcity and variability, and reduce the need for external water sources and energy for pumping.
Some common water harvesting and storage practices include:
- Rainwater harvesting: Use systems that collect and store rainwater from rooftops, greenhouses, and other impervious surfaces, such as cisterns, tanks, and ponds, for later use in irrigation or livestock watering.
- Stormwater management: Use practices that slow down, spread out, and soak in stormwater runoff from fields, roads, and other areas, such as vegetated buffers, swales, and infiltration basins, to reduce erosion and flooding, and recharge groundwater.
- Managed aquifer recharge: Use practices that intentionally add water to aquifers, such as injection wells, infiltration basins, and permeable pavements, to store water underground for later use, and to mitigate groundwater depletion and subsidence.
- On-farm ponds and reservoirs: Use structures that store water on the farm, such as excavated or embankment ponds, and small reservoirs, to provide water for irrigation, livestock, and other uses, and to create aquatic habitats and recreation opportunities.
By using these practices, farmers can increase water availability and reliability, reduce water costs and energy use, and enhance the resilience and sustainability of their operations (Vickers, 2018).
Crop Selection and Breeding
Crop selection and breeding is the practice of choosing and developing crop varieties that are well-adapted to local climate, soil, and water conditions, and that have desirable traits, such as drought tolerance, water use efficiency, and yield stability. Crop selection and breeding can help optimize water use and productivity, and reduce the risk of crop failure and economic losses under water stress.
Some strategies for crop selection and breeding include:
- Drought-tolerant crops: Use crops that have evolved or been bred to withstand water stress, such as sorghum, millet, cowpea, and quinoa, which have deep roots, waxy leaves, and other adaptations to conserve water and maintain growth under drought.
- Water-efficient crops: Use crops that have high water productivity, or the ratio of crop yield to water use, such as maize, wheat, and rice, which have been bred for high yield potential and water use efficiency.
- Native and perennial crops: Use crops that are native to the local region, or that have perennial growth habits, such as grasses, shrubs, and trees, which have deep and extensive root systems, and can access water from deeper soil layers and groundwater.
- Crop diversification: Use a diverse mix of crops, including legumes, forages, and cover crops, to spread risk, optimize resource use, and provide multiple ecosystem services, such as nitrogen fixation, soil health, and biodiversity.
By using these strategies, farmers can reduce irrigation water use by 10-30%, increase crop yields by 20-50%, and enhance the resilience and sustainability of their cropping systems under water stress (Langridge & Reynolds, 2021).
Agroforestry and Silvopasture
Agroforestry and silvopasture are practices that integrate trees, shrubs, and other perennial plants with crops and livestock, to create diverse, productive, and resilient agricultural systems.
Agroforestry and silvopasture can provide multiple water-related benefits, such as:
- Reducing evapotranspiration and water stress: Trees and shrubs can provide shade, windbreaks, and mulch, which can reduce soil and plant evaporation, and moderate temperature and humidity, thus conserving water and reducing crop water requirements.
- Improving soil water holding capacity and infiltration: Trees and shrubs can add organic matter, create soil macropores, and stimulate soil biological activity, which can improve soil structure, porosity, and water retention, and reduce runoff and erosion.
- Accessing and redistributing water from deep soil layers: Trees and shrubs can have deep and extensive root systems, which can access water from deeper soil layers and groundwater, and redistribute it to shallow soil layers and crops through hydraulic lift and redistribution.
- Providing alternative water sources and products: Trees and shrubs can provide alternative water sources, such as dew, fog, and stemflow, and alternative products, such as wood, fruit, fodder, and medicine, which can diversify income and reduce the reliance on irrigated crops and pastures.
By using these practices, farmers can reduce irrigation water use by 30-50%, increase crop and livestock yields by 20-100%, and enhance the resilience and sustainability of their agroecosystems under water stress (Ong et al., 2015).
Challenges and Opportunities
While water conservation and management practices can provide many benefits for sustainable agriculture, they also face some challenges and barriers to adoption, such as:
- Knowledge and skills: Implementing water conservation and management practices requires a deep understanding of hydrology, agronomy, and ecology, as well as practical experience and adaptive management skills.
- Equipment and infrastructure: Some practices, such as precision irrigation, water harvesting, and agroforestry, may require specialized equipment or infrastructure, such as sensors, pumps, storage tanks, and tree nurseries, which can be expensive or unavailable.
- Economic and policy incentives: Water conservation and management practices may have higher upfront costs or lower short-term returns than conventional practices, and may not be eligible for government subsidies or insurance programs that are based on yield or acreage.
- Social and cultural norms: Adopting water conservation and management practices may require a shift in mindset and behavior, and may face resistance from family, neighbors, or industry partners who are used to conventional practices.
Despite these challenges, there are also many opportunities and resources available to support farmers and land managers in adopting water conservation and management practices, such as:
- Research and education: A growing body of scientific research and practical knowledge on water conservation and management is available through universities, extension programs, and farmer networks, which can help farmers learn and adapt best practices to their local context.
- Financial and technical assistance: Government agencies and non-profit organizations offer financial and technical assistance programs to help farmers implement water conservation and management practices, such as the Environmental Quality Incentives Program (EQIP), the Conservation Stewardship Program (CSP), and the Regional Conservation Partnership Program (RCPP) in the US.
- Market and consumer demand: A growing segment of consumers and food companies are demanding more sustainable and water-efficient agricultural products, which can create market opportunities and premiums for farmers who adopt water conservation and management practices.
- Ecosystem services and water markets: Water conservation and management practices can provide ecosystem services, such as water quality, flood control, and biodiversity, which may be valued and compensated through emerging markets and payment schemes, such as water quality trading, flood insurance discounts, and biodiversity offsets.
Conclusion
Water conservation and management is a critical issue for sustainable agriculture, as water scarcity and variability become more pressing challenges in many regions of the world. By adopting practices such as irrigation scheduling, precision irrigation, soil health management, water harvesting, and storage, crop selection and breeding, and agroforestry and silvopasture, farmers and land managers can optimize water use efficiency, reduce water losses and degradation, and enhance water quality and ecosystem services.
However, adopting water conservation and management practices also faces challenges and barriers, such as knowledge and skill gaps, equipment and infrastructure needs, economic and policy disincentives, and social and cultural norms. Overcoming these challenges will require a concerted effort from researchers, educators, policymakers, and market actors to provide the knowledge, resources, incentives, and support that farmers need to transition to water-smart agriculture.
Ultimately, managing water resources in agriculture is not just a technical or economic issue, but a moral and ethical imperative. As stewards of the land and water, we have a responsibility to use and conserve these precious resources wisely and equitably, for the benefit of current and future generations. By embracing water conservation and management as a cornerstone of sustainable agriculture, we can create a more resilient, productive, and sustainable food system that nourishes people and the planet.