Low-Pressure Sprinkler Systems
alternative practice names:
Low-Elevation Sprat Application (LESA); Low-Energy Precision Application (LEPA)
A sprinkler system uses a distribution system to apply water through a nozzle that is operated under pressure. The purpose of a sprinkler system is to uniformly and efficiently apply water to crops. Sprinklers were originally designed for high pressures, which resulted in low water application efficiency, significant evaporation losses, and high energy consumption.
Modern nozzle designs for water application have enabled all types of sprinkler systems to operate effectively at lower pressures, reducing energy requirements and ensuring that most of the pumped water reaches the crops when positioned correctly. To achieve high application efficiency with low pressure, applicators need to be spaced closer together and positioned lower to the ground. Generally, operating pressures between 2-35 psi are considered low.
The most common low sprinkler system in use today is the center pivot. Water application with pivots is most efficient when applicators are positioned within 18 inches of ground level. Most of the newer nozzles have interchangeable “deflector” pads, which allow various spray patterns and bubble modes, enabling quick and easy switching from one water application mode to another.
Common systems are:
Low-Elevation Spray Application (LESA) is a non-bubble spray applicator that is more versatile across various crops, row orientations, and sloped terrains.
Low-Energy Precision Application (LEPA) is a bubble applicator that has a higher water use efficiency.
This practice could involve converting from a surface or less efficient irrigation system, replacing an existing high-pressure sprinkler system, or retrofitting an existing high-pressure sprinkler with low-pressure nozzles.
When used, in what regions in the U.S. is the practice found:
Northwest, West, Upper Midwest, Southwest, Southeast
FARM SIZE
When used, typically found on farms of the following sizes:
All Sizes
Practice Benefits
Reduced energy consumption: Low-pressure sprinkler systems require less energy to operate as they utilize pumps running at lower pressures. This reduction in pressure and flow rate leads to lower electricity costs, offering farmers a quick return on investment. However, it is important to note that switching from surface irrigation may increase overall energy expenses.
Water savings: Operating at lower pressure levels generates larger water droplets, which are less prone to wind drift and evaporation. Additionally, these systems apply water closer to the soil surface, avoiding the wetting of the plant canopy in row crops. This enhances application efficiency and reduces the total water required for irrigation.
Improved uniformity in root zone coverage: The larger water droplets produced by low-pressure systems ensure more consistent coverage of the root zone, leading to more uniform soil moisture levels and better crop health.
Potential of increased yields: Low-pressure sprinkler systems can ensure a more even application of irrigation water across a field, resulting in increased yields in areas prone to water losses due to wind or drift.
Implementation Insights
Site-specific or Farm-specific requirements
Irrigation system: Most farms with irrigation systems have the opportunity to convert or replace them with low-pressure sprinklers.
Required Capital Expenditures (CapEx)
System upgrades: When upgrading from a high-pressure system to a low-pressure system, capital expenditures can range widely. Retrofitting an existing center pivot with a low-pressure nozzle is minimal compared to purchasing the original sprinkler system.
System conversion: When converting from a surface irrigation system, the initial cost can be substantial to the purchase of a new center pivot sprinkler or linear system. Additional costs may be incurred for pipelines necessary to transport water to the sprinkler and a power supply to furnish pressure.
Required Operational Expenditures (OpEx)
Maintenance: When upgrading from a high to a low-pressure system, the maintenance labor is comparable to that required for other sprinkler systems. Regular operations and maintenance include clearing debris from nozzles, inspecting nozzle and spray heads for wear, checking pipelines, and performing routine maintenance on pumping plant components and other mechanical parts as recommended by the manufacturer.
System management: When converting from a surface irrigation system, labor requirements are lower. Surface irrigation systems can easily be automated. However, sprinkler irrigation requires more advanced management compared to surface methods. Unlike flood irrigation, which saturates the entire soil profile at once, sprinklers apply water in smaller, more frequent doses to meet specific crop needs. This precision increases the risk of crop failure if soil moisture, crop evaporative demand, and soil salinity are not closely monitored. Skilled and well-trained labor is essential for effective management.
Implementation Considerations
When upgrading from a high- to a low-pressure irrigation system, operators will need to evaluate automation options that accompany many of the newer low-pressure sprinkler systems. The following complexity should be considered:
Technical assistance: Irrigators may need technical assistance to assess whether specific options are suitable for their crops, soil conditions, and regional factors. This expertise is essential for making informed and effective irrigation decisions.
When converting from a surface irrigation system, there are added complexities:
Manure application: Farmers interested in fertigating crops with manure water will need to remove course and fine solids before directing water through sprinkler irrigation systems, which can add significant expenses.
Salinity issues: Sprinkler systems have lower flow rates, which are insufficient to move salts through the soil profile and out of the root zone. As a result, salts tend to accumulate in the topsoil, necessitating periodic flooding to prevent soil degradation.
Reduced production area: In pivot systems, the corners of fields may be removed from production, reducing the overall crop area.
Financial Considerations and Revenue Streams
FEDERAL COST-SHARE PROGRAM
Funding is available for this practice through USDA's Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP) and the Conservation Stewardship Program (CSP).
Related EQIP Practice Standard: Irrigation Water Management (449).
Related CSP Enhancement: Intermediate IWM - 20% Reduced Water Usage (E449J).
Notes:
Check with the local NRCS office on payment rates and crop rotations relevant to your location.
Environmental Impacts
REDUCES FARM GREENHOUSE GAS FOOTPRINT
Operating irrigation systems at lower pressure reduces the energy required to pump water, which in turn lowers electricity consumption. Since electricity generation often involves burning fossil fuels, reducing energy use leads to lower greenhouse gas (GHG) emissions associated with power production.
CONSERVES WATER
Low-pressure irrigation systems are designed to produce larger droplets, significantly minimizing evaporation loss. These larger droplets reduce the likelihood of water vaporizing before reaching the soil surface, thereby conserving water resources and maximizing irrigation efficiency. Additionally, the larger droplets are better suited for penetrating the soil and reaching plant roots, ensuring water is delivered precisely where it is needed most. This method can achieve water application efficiencies of 95-98%, making it highly efficient in water usage.
See research highlights:
Peters et al. (2016) found that 18% more water reached the ground with LESA when compared with MESA system.
Bordovsky et al. (2019) demonstrated that crops irrigated using the LEPA system yielded 16% more than traditional sprinkler methods at low irrigation levels (≤50% of full irrigation). At higher irrigation levels, the yield difference between LEPA and sprinkler systems was minimal.
IMPROVES WATER QUALITY
By applying water closer to the soil surface and often using soil surface modifications (such as basin tillage), LEPA systems minimize water runoff and soil erosion, further enhancing the sustainability of the irrigation practice.
REFerences
Alignment with FARM Program
FARM Environmental Stewardship (ES) V2-V3 Alignment
The optional FARM ES Conservation Practice Questionnaire (CPQ) asks about irrigation stewardship methods.
Contents
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
A sprinkler system uses a distribution system to apply water through a nozzle that is operated under pressure. The purpose of a sprinkler system is to uniformly and efficiently apply water to crops. Sprinklers were originally designed for high pressures, which resulted in low water application efficiency, significant evaporation losses, and high energy consumption.
Modern nozzle designs for water application have enabled all types of sprinkler systems to operate effectively at lower pressures, reducing energy requirements and ensuring that most of the pumped water reaches the crops when positioned correctly. To achieve high application efficiency with low pressure, applicators need to be spaced closer together and positioned lower to the ground. Generally, operating pressures between 2-35 psi are considered low.
The most common low sprinkler system in use today is the center pivot. Water application with pivots is most efficient when applicators are positioned within 18 inches of ground level. Most of the newer nozzles have interchangeable “deflector” pads, which allow various spray patterns and bubble modes, enabling quick and easy switching from one water application mode to another.
Common systems are:
Low-Elevation Spray Application (LESA) is a non-bubble spray applicator that is more versatile across various crops, row orientations, and sloped terrains.
Low-Energy Precision Application (LEPA) is a bubble applicator that has a higher water use efficiency.
This practice could involve converting from a surface or less efficient irrigation system, replacing an existing high-pressure sprinkler system, or retrofitting an existing high-pressure sprinkler with low-pressure nozzles.
Practices and technologies
Low-Pressure Sprinkler Systems
alternative practice name:
Low-Elevation Sprat Application (LESA); Low-Energy Precision Application (LEPA)