Effective irrigation and water management are crucial for successful agriculture, gardening, landscaping, or anything to do with growing crops. Irrigation management is essential for optimizing water use, maintaining crop health, and ensuring sustainable farm operations. You will save time and money by preparing a plan before you ever set anything up.
Implementing the following practices can increase the efficient use of irrigation on your farm or growing system. The higher the efficiency, the fewer nutrients lost and better environmental and economic outcomes. But before that, you need to learn and understand the specific irrigation practices for better farming outcomes. Read on to learn more about best practices for managing irrigation and water needs on your farm.
Assessing Water Needs
Assessing crop water needs is a crucial component of irrigation management, ensuring that crops receive the right amount of water for optimal growth and yield without overuse or waste. It's important to develop an understanding of your crop's water needs so it can develop and grow into a healthy crop.
Understanding Factors Influencing Crop Water Requirements
Understand the Water Requirements of your Crop: Determine the specific water needs for each crop based on their species, growth stage, and your local climate conditions.
Understand your Soil: Consider other environmental factors like soil type, clay, root depth, and canopy cover when assessing water requirements.
Clay: less than 0.002mm
Silt: 0.002-0.05mm
Sand: 0.05-2mm
Stones: bigger than 2mm in size
Chalky soils also contain calcium carbonate or lime
Understand and Calculate Evapotranspiration Rates (ET):
Many factors go into ET such as; solar radiation intensity, air temperature, wind speed, humidity, vegetative leaf area of the plant, and the stage of the plant roots. These are called your potential evapotranspiration (PET) or ET₀.
You can use these factors to estimate water loss through evaporation and plant transpiration. It's understandable that during drought conditions plants may not be able to extract water fast enough to keep up with evapotranspiration and you will have to compensate.
These variables change seasonally in the United States but may change hourly or even minute-to-minute. You may need to adjust irrigation schedules based on weather conditions and ET data. Take a look at your local weather station to help you find your PET / ET₀.
You can also find climate data in Farmbrite. It offers weather insights in-app as well as national weather and climate data in charts and graphs. This gives you historical data at your fingertips but you can also create climate gauges to keep track of specific areas on your farm. You can track weather, temperature, humidity, or anything that is of interest to growing better crops.
Calculating Evapotranspiration Rates
Calculating ET can be a bit complicated because you will be considering soil-water balance, aerodynamic and surface resistance as well as other factors. There are many variables and coefficients in these equations but we will try to make it a little more easy to understand. There are several methods to calculate your evapotranspiration. Each has variables that they take into account. Some are better for more arid areas and some have taken out some variables to be easier to calculate. Below you will find information on the different methods but here are calculators to help you with these sometimes complicated equations.
Here is an Evapotranspiration Calculator created by the Food and Agriculture Organization of the United Nations. This is a desktop version that can be downloaded on your computer.
Here is an Evapotranspiration Calculator created by the EPA. It has both a BETA version and a desktop version. It was created with watershed modeling and climate change assessments in mind.
Here is a calculator that was created in collaboration with several Canadian Universities and the Canadian government. It outlines the formulas and the various methods.
Evapotranspiration Methods:
As we've discussed there are many methods to calculate ET. They each have their benefits and considerations. Please do more research on which method might be the best for your area and your crops and double-check your calculations.
The Penman-Monteith Method (PM):
The PM method is a widely used calculation and is a highly regarded and used approach for estimating evapotranspiration (ET), specifically reference evapotranspiration (ET₀). It is considered one of the most accurate methods for estimating ET because it incorporates various climatic factors, including temperature, humidity, wind speed, and solar radiation.
The Penman-Monteith method is often recommended by the Food and Agriculture Organization (FAO) and other agricultural and environmental organizations for its robustness and accuracy.
The Thornthwaite Method (TH):
The TH method or The Thornwaite-Mather equation is a widely used technique to estimate potential evapotranspiration (PET), which represents the theoretical amount of water that would be evaporated and transpired from a given area, considering climate and vegetation factors. Developed by Charles W. Thornthwaite in 1948, the method primarily relies on temperature data and is known for its simplicity and applicability in various climatic regions.
Additional Considerations
The Thornthwaite method also includes an adjustment for the length of daylight hours, as evapotranspiration rates vary with day length.
The method has limitations in that it relies heavily on temperature, without accounting for other factors like humidity, wind, and solar radiation. Despite this, it has been widely used due to its simplicity and reasonable accuracy for estimating PET in many climatic scenarios.
The Blaney-Criddle Method (BC):
The BC method is a traditional approach used to estimate evapotranspiration (ET), specifically in the context of agricultural water planning and irrigation. This method is known for its simplicity and relies on temperature and the percentage of annual daylight hours during the growing season. Modifications of the Blaney-Criddle method, such as incorporating additional climatic variables or using regional calibration, can improve accuracy.
The Priestley-Taylor Method (PT):
The PT method is a simplified approach to estimate potential evapotranspiration (PET) or reference evapotranspiration (ET₀), derived from the Penman-Monteith method. It is primarily used when detailed meteorological data (like wind speed and humidity) are unavailable or when a simplified estimation approach is desired.
Developed by C.H.B. Priestley and R.J. Taylor in 1972, the method eliminates the need for wind speed and humidity data by making an assumption about the ratio between actual evapotranspiration and the available energy. This ratio is represented by an empirical constant, alpha (𝛼α), simplifying the calculation of PET.
The Hargreaves Method (HA):
The HA method is temperature-based and takes into account solar radiation in a 24 hour period.
The Abtew Method (AB):
The AB method or the radiative Abtew model The Hargreaves method is a simplified empirical approach to estimate reference evapotranspiration (ET₀), commonly used in agricultural planning and water resource management. It is particularly useful when detailed meteorological data required by more complex methods like the Penman-Monteith are not available. The Hargreaves method relies primarily on temperature data and incorporates the daily temperature range to estimate ET₀.
Eddy covariance technique:
The Eddy Covariance also known as eddy correlation or eddy flux, is a method used to measure and analyze vertical fluxes of gases, heat, and momentum in the atmosphere. This technique is commonly used in atmospheric sciences, ecology, and meteorology to study the exchange of carbon dioxide (CO₂), water vapor, methane (CH₄), and other trace gases between the surface and the atmosphere. It is often used in micro-climates.
As you can see there are multiple ways to calculate evapotranspiration. You might use any one of these methods, try a calculator, or all of the above to help you meet the irrigation needs of your farm. As we're discussing precision agriculture here, let's talk about soil moisture monitoring next.
Soil Moisture Monitoring:
Soil monitoring plays a crucial role in agriculture, landscaping, and environmental studies by providing valuable data on soil conditions. This is done through the use of sensors. These sensors help in optimizing irrigation, managing soil health, and ensuring sustainable farming practices.
There are many types of sensors that you can opt to have on your farm. Here are some types of sensors and their uses.
Soil Moisture Sensors
Capacitance Sensors: These sensors measure the change in capacitance caused by variations in soil moisture. (Capacitance is a method of measuring the amount of water in soil through its capacity to transmit electromagnetic waves or pulses). This is commonly used in agricultural applications due to their fast response and cost-effectiveness.
Tensiometers: These sensors measure soil water tension or matric potential, which means they indicate how much energy plants need to extract water from the soil. Often they are used to determine irrigation needs and to monitor plant stress levels.
Time-Domain Reflectometry (TDR) Sensors: TDR sensors measure the dielectric constant of soil, which is related to moisture content in the soil. They are known for their high accuracy and versatility in various soil types.
Frequency-Domain Reflectometry (FDR) Sensors: Similar to TDR sensors, but FDR uses high-frequency signals to measure soil moisture. These are often used in precision agriculture and research due to their accuracy.
Soil Temperature Sensors
Thermocouples: These consist of two different metals that produce a voltage proportional to temperature. They are used to monitor soil temperature, which can impact plant growth and nutrient uptake.
Thermistors: Is a type of resistance thermometer that is temperature-dependent resistance to measure soil temperature. These are commonly used due to their sensitivity and range of applications. They are made with metallic oxides.
Soil Nutrient Sensors
Ion-Selective Electrodes (ISEs): Measure specific ions, such as nitrate, potassium, or phosphate, in the soil. They are useful for monitoring nutrient levels and guiding fertilization practices.
Electrical Conductivity Sensors: Measure the conductivity of soil, which is influenced by the concentration of dissolved salts and nutrients. Often used to assess soil salinity and guide fertilization and irrigation.
Soil pH Sensors
Glass Electrode pH Sensors: Measure soil acidity or alkalinity by detecting hydrogen ion activity. They are useful for determining soil pH and guiding soil amendment practices.
Solid-State pH Sensors: More durable than glass electrodes, these sensors are used for long-term monitoring in harsh conditions.
Soil Gas Sensors
Carbon Dioxide (CO2) Sensors: Measure CO2 levels in the soil, which can indicate soil respiration and microbial activity. They are useful for assessing soil health and decomposition rates.
Oxygen Sensors: Measure oxygen levels in the soil, indicating soil aeration and drainage. Important for monitoring conditions that affect root growth and soil organisms.
Soil Structure Sensors
Penetrometers: Measure soil compaction and resistance to penetration. They are used to assess soil structure and determine the need for soil aeration or tillage.
TDR and FDR Probes: Apart from measuring moisture, these probes can also provide information on soil density and structure.
Lysimeters:
Lysimeters are not sensors themselves but are devices used to measure the amount of water that permeates through the soil and the dissolved substances carried with it. The use of lysimeters in agriculture has brought much more information to soil science, agricultural research, and hydro and environmental studies. It records the amount of precipitation in an area and the amount lost through the soil. This measurement is crucial for understanding processes like evapotranspiration, leaching, and water movement within soil profiles.
Weighing Lysimeters:
These lysimeters are designed to measure changes in weight over time, allowing researchers to quantify water loss through evapotranspiration. They usually consist of a container filled with soil and plants, placed on a scale or load cells to measure weight changes due to water loss and gains through precipitation or irrigation.
Drainage Lysimeters:
These lysimeters are designed to collect and measure the quantity and quality of water that drains through the soil profile. They often consist of a container or a designated plot with a collection system at the bottom to capture percolating water. The collected water can then be analyzed for dissolved substances, such as nutrients, pollutants, or other chemicals.
Now that we've gone over calculations and sensors you might use to help give you specific data about your soil, and water use, let's talk about irrigation best practices.
Best Practices for Managing Irrigation and Water Needs on Your Farm
Irrigation best practices can be any set of techniques, technologies, and management strategies that aim to optimize water use in agriculture while promoting sustainability, crop health, and resource efficiency. Implementing these practices can increase crop yield, reduce water waste, and minimize environmental impacts. We will break down some of the things you may want to take into account when creating your irrigation plan.
1. Assess Water Needs and Crop Requirements
Evaluate Your Soil: It's important to understand the characteristics of your soil. Different soils can hold varying amounts of water and can affect water retention and drainage.
Evaluate the Needs of Your Crops: Understanding the specific water needs of your crops is vital and is where the calculations above can help. Different crops require varying amounts of water and climate factors like temperature, rainfall, humidity, and wind all go into planning irrigation schedules.
2. Choose the Right Irrigation System
Choosing the right farm irrigation system is another important step in your operation. You will want to take into account a few things like the type of crop, your budget, the size of your farm, and more.
What is the Right Irrigation System:
Select a system that suits your farm's layout, crop types, and water availability. Common systems include drip irrigation, sprinklers, center pivots, and furrow irrigation. Let's get into specifics.
Drip Irrigation: Ideal for precise watering at the plant's root zone, minimizing evaporation and runoff. It’s suitable for various crops, including fruits, vegetables, and trees. Drip irrigation is typically the most efficient, providing water directly to the root zone with minimal evaporation. These hoses are usually prefilled with holes and ideally, you would plug the spots that a plant is not.
Sprinkler Irrigation: Effective for broad coverage but may be subject to wind and evaporation losses. This is commonly used for field crops and lawns. Some types of plants are prone to leaf issues with this type of irrigation.
Center Pivot and Linear Move Systems: Useful for large-scale field irrigation, providing uniform water distribution over large areas. Can be pricey for the setup.
Surface Irrigation: Also known as flood irrigation, includes furrow and basin irrigation and is generally used for row crops. It can be less efficient due to runoff and uneven distribution.
As we've mentioned it's important to take many of these types of irrigation options into account before making a choice. See more about these types of irrigation below.
3. Implement Advanced Irrigation Technologies
If you have the means you might want to look into some advanced irrigation options. Here are are few options to look into.
Smart Controllers: Use weather-based or soil moisture-based controllers to adjust irrigation schedules automatically based on current conditions.
Soil Moisture Sensors: These sensors monitor soil moisture levels, helping to ensure that irrigation occurs only when necessary, reducing over-irrigation.
Weather-Based Systems: You might incorporate weather data to adjust irrigation based on rainfall, temperature, and other climatic factors. There are more and more weather monitoring systems popping up as the climate changes. We find clients like to monitor their mico-climate with these.
Remote Monitoring and Control: Allows farmers to monitor and control irrigation systems remotely, enhancing flexibility and responsiveness.
4. Optimize Irrigation Schedules
Based on timely measurements or estimations of soil moisture content and crop water needs, proper irrigation scheduling is one of the best irrigation management practices. Irrigation scheduling is a generic term for scheduling the time and amount of water applied to a crop based on the amount of water present in the crop root zone, the amount of water needed by the crop, and other factors such as salt leaching requirements, etc.
Irrigation scheduling is essential to reduce water wastage or apply insufficient water. Incorrect irrigation has two consequences, either stunted growth or water wastage. Effective irrigation scheduling will conserve labor, resources, and plant nutrients and you'll need to consider the following essential parameters when preparing an irrigation schedule.
Optimal Timing: Irrigate during the early morning or late evening to reduce evaporation losses. Avoid midday irrigation when the sun is strongest or during windy weather.
Irrigation Frequency and Duration: Adjust based on soil type, crop stage, and weather conditions. Aim for deep, infrequent irrigation to encourage strong root growth. Adjust irrigation frequency and volume according to the growth stage of each crop. Provide more water during critical growth periods, such as flowering or fruiting, and less during dormancy or after harvest.
Water Budgeting: Calculate and adhere to a water budget based on crop water needs and available water resources. Implement mulching to reduce evaporation and improve soil moisture retention. Consider using cover crops to improve soil health and reduce water needs.
Understanding Your Weather: Micro-climates force us to adjust irrigation schedules due to weather changes in our area. These micro-climates make the weather of our properties localized. Your climate may differ from your neighbor who has a lot of tree cover.
5. Implement Water Conservation Practices
There is much that can be done to conserve water. Determining irrigation water use is essential as it informs the farmer of the amount of irrigated water, helping you see the irrigation system's performance. You can measure it directly using a meter or a periodic manual measurement. Or measure indirectly by determining energy, irrigation water pressure, and more.
This practice will help you know the cost associated with water use and will trigger the need to integrate water conservation measures to reduce the cost. Also, it will help you understand when the irrigation appliances are not functioning correctly.
Mulching: Apply mulch to retain soil moisture and reduce evaporation.
Cover Crops: Use cover crops to protect soil, reduce erosion, and retain moisture.
Rainwater Harvesting: Collect and store rainwater for irrigation to reduce dependency on external water sources. (This may not be available in all areas of the country so check your area.)
Use Reclaimed Water: If available and safe, reclaimed or recycled water can supplement irrigation.
6. Regular Maintenance and Monitoring
You need to know the total water used in on-farm irrigation and identify opportunities to improve water use efficiency. The water audit will gather information about field size and shape, obstructions, topography, flood vulnerability, type of equipment, and costs. An on-farm irrigation audit will help you improve the system's efficiency and reduce costs.
System Maintenance: Regularly check irrigation systems for leaks, clogs, or other issues that could affect efficiency.
Calibration: Ensure that sensors and controllers are properly calibrated to provide accurate data for your farm. You will want to do this each season.
Monitor Water Use: Track water use to identify trends and opportunities for improvement.
7. Sustainable Practices and Regulations
New technologies and sustainable practices will be more available as we research and continue to make progress in agriculture.
Follow Local Water Regulations: In some parts of the U.S., there are water restrictions. It's important to understand your local water use regulations and restrictions.
Education and Training: Keeping up to date with new technologies and continuously educating yourself and your team on best practices, new technologies, and sustainable irrigation methods will help you understand how to improve your farm. It doesn't mean that you will always use those methods right away. But they are interesting to learn about and keep in mind for the future.
These best practices are the basics and by implementing some or all of these practices, farmers and agricultural managers can achieve efficient irrigation that supports crop health, conserves water, and promotes environmental sustainability. There are more ways to improve the ability of your soil to hold moisture, that is through no-till or low-till techniques.
Conservation Tillage (No-Till) and Crop Residue Management
Tilling has been a conventional practice of farming for many years. It can be hard on the land so conservation tillage practices like low-till or no-till methods are being used more and more on farms.
These techniques improve the ability of the soil to hold moisture and reduce the amount of water that runs off from the field. Also, it reduces the amount of water evaporation from the soil surface.
However, not all irrigation systems can incorporate conservation tillage. Surface irrigation systems such as furrow irrigation will not achieve their maximum possible efficiency and application uniformity as residue can obstruct water flow and prevent water from passing through it.
The benefits of no-till will vary with climate and irrigation method practiced, such as;
Land leveling: Land leveling is a system based on topographic surveys, and it's used to increase uniformity with which water is applied to an irrigated field. If you have more than one irrigation method or crop, leveling should be according to the most restrictive method and yield. You can level a farm that has never been graded or ground before preparing seed beds. Land leveling helps in nutrient retention as it reduces runoffs. You can use a laser-controlled scraper pulled by a tractor for better leveling. The laser has a predetermined cross, runs slopes, and automatically adjusts the cut of filled land over the plane of the field.
Furrow dikes: Furrow dikes are a system where small earthen dams are constructed at intervals along the furrows to reduce runoff from the soil surface and increase water infiltration. It's a technique in which water is applied to the field to form a water layer that infiltrates the soil. Its use is limited to gently sloppy land. Still, it is primarily used in areas for row crops to capture rainfall, reduce runoff, and improve the uniformity of low-pressure sprinkler irrigation systems. They are typically installed when the crop bed is prepared before planting or after planting but before the crop height could reach one that installing dikes could cause damage. You can remove furrow dikes if the increase in moisture is causing adverse effects on production or harvesting.
Drip irrigation: Drip irrigation is the slow application of water directly to the plant root zone using particular delivery items. It is advantageous as it leads to uniformity, preservation of soil structure, reduction in evaporation, better water control, and nutrients reaching the plant. The use of a drip system is not primarily to reduce water wastage but to increase crop yield and quality. In this application, you might want to consider a situation where natural precipitation or stored soil water is insufficient for germination so you can ensure the system can provide sufficient water to germinate the seed. Also, you'll need to maintain and monitor issues regarding clogging and back flushing of emitters, monitor application pressure, and replace the equipment. You can inject cleaning agents depending on the drip irrigation system specification. For instance, if you're using ditch water you might have a lot of silt that builds up, and drip irrigation might not be the best option.
Linear move sprinkler irrigation system: The system contains a series of towers that suspend the irrigation system and irrigate along the rows of your farm. Usually, they're supplied by water from a source adjacent to the first tower and parallel to the direction of the move by a flexible hose that, in turn, provides water through a series of risers connected to a buried pipeline. This can also be managed through hoses or other means. This type of system is ideal where a center pivot irrigation may not be available due to the shape of the field, elevation, or the farm layout. It works with many areas and soil types as well as a wide variety of crops. You can use low-pressure and high-pressure systems, but the best practice for irrigation recommends low-pressure because they have a higher water application efficiency than high-pressure systems. Also, you can convert high or medium-pressure designs to low-pressure to achieve better results.
Other Conservation Best Practices for Irrigation Include;
Place plant species and pot sizes with similar water needs in the same watering zone.
Ensure each watering zone has spray emitters with similar flow rates to maintain uniformity.
Make system upgrades and improvements, and repair the system equipment.
Ensure that appropriate filtration is used, regularly clean filters, and flush and unclog the emitters.
Use an on/off valve to prevent runoff while hand watering.
Consolidate plants and turn off irrigation in unused portions to avoid wastage.
Avoid irrigating outdoors in windy seasons.
Regularly change the irrigation schedules to reflect changes in weather, crop needs, or soil moisture values.
Use suitable and uniform nozzle sizes and sprinkler heads with a high uniformity rating.
Consider converting to an irrigation system with high potential uniformity if irrigation uniformity remains an issue after several improvements.
Final Thoughts on Irrigation Management
Learning about the best irrigation is essential for all crop farmers. The goal of effective irrigation management practices is to efficiently and effectively utilize your water resources. Applying smart irrigation techniques and conservation practices will help prevent water contamination, improve management practices, and will be beneficial to the farm overall.
Your farm can optimize its irrigation management, leading to improved crop yields, reduced water usage, and enhanced sustainability.
If you'd like more information about how our farm Management Software, Farmbrite might help your farm give us a try for free for 14 days.
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