Nitrate Measurement in Turf Grass
Nitrate concentration in grasses can be used as an indicator of soil nitrogen (N) availability for their growth. Research at the University of Connecticut suggests verdure sap nitrate-N concentrations at 200-300 ppm as the optimum level.
Introduction
Grasses store nitrogen (N) as nitrate in the bases of stems and shoots. Research conducted by Guillard and Morris (2013) at the University of Connecticut suggests that nitrate accumulate in the shoot bases of perennial turf grasses during the fall (when new leaf blade formation declines), which could be a significant source of N for the turf plant at the onset of new growth in the following spring after winter dormancy. At the optimum critical level of nitrate-N concentration and beyond, the turf response will plateau or flatten out – increasing the fall verdure nitrate-N concentrations with more fertilizer beyond the optimum critical level will not increase the grass quality in the fall or the following spring; the maximum quality response has been reached.
Pocket-sized LAQUA twin Nitrate Ion meter was used to measure nitrate-N concentrations in verdure sap. It eliminates the need to transport samples to a laboratory for expensive analysis performed using either colorimetry or chromatography by trained analyst.
Method
Calibrate the LAQUAtwin Nitrate Ion meter according to manufacturer’s instructions.
Sample Collection And Preparation
- Mow the turf to desired height and remove mowed clippings.
- Collect verdure samples—aboveground parts of the turf plant remaining after clippings removed. A golf-ball sized, compressed verdure sample is usually sufficient to produce adequate sap for the test.
- Squeeze the sap from the verdure sample using a hydraulic or garlic-type press.
Sample Measurement
- Place some drops of the extracted sap directly into the sensor.
- Record the reading once stabilized—☺ appears.
- After each sample, rinse the sensor with water and blot it dry with tissue.
Place some drops of the extracted sap directly into the sensor.
Record the reading once stabilized—☺ appears.
Results and Benefits
Research at the University of Connecticut suggests that no fertilizer is required in the fall if the verdure sap nitrate-N concentrations are 200-300 ppm or above during October through November in their climate (critical values were based on turf mowed to a height of 2¼ inches and test was conducted using Horiba’s LAQUA twin Nitrate ion meter). If less than 200, it suggests that some nitrogen be applied to obtain optimum turf responses. When readings are between 100 to 200 ppm, 0.25 to 0.33 lbs N/1000ft2 can be considered. If readings are less than 100 ppm, then 0.33 to 0.50 lbs N/1000ft2 can be considered, provided that N is applied before the onset of winter.
Reference
Guillard, Karl and Morris, Thomas. The Verdure Sap Nitrate Test To Guide Fall N Fertilization of Turf Sod. Sod Nutrient Management Technical Guide TG-0265-R1, June 2013
Matching products
Precise Nitrate Tester for Plants – Mobile NO₃⁻ Analysis On-Site Horiba Nitrate Ion Pocket Tester Kit for fast and accurate on-site results The Horiba LAQUAtwin Nitrate Ion Hand Tester (NO3-11C) in its practical analysis kit is your mobile laboratory for reliable determination of nitrate ions and temperature in plant sap samples. With a wide measurement range of 6 to 9900 ppm NO₃⁻ and automatic temperature compensation, the device provides fast and accurate results. The ion-selective electrode ensures precise NO₃⁻ measurements, while the digital backlit display allows quick and easy reading of values. Mobile nitrate analysis kit for plants, water, and environmental monitoring The kit contains the handheld tester, five pipettes, three measuring cups, a plant sample press, standard solutions, and sampling sheets. This setup allows for rapid and reproducible analysis of plant sap without the need for additional laboratory equipment. The device is dust- and waterproof, features automatic standard recognition, Auto-Stabil and Auto-Hold functions, and has a long battery life, making it ideal for mobile use in the field, greenhouse, or laboratory. Why nitrate measurement in plants is important – and why a mobile kit is ideal Nitrate content in plants is a key indicator of nutrient supply, plant growth, and agricultural product quality. Excessively high or low nitrate levels can negatively impact yield, plant quality, and environmental compatibility. A mobile nitrate hand tester allows direct analysis of plant sap on-site, without time-consuming laboratory procedures. Fertilization and irrigation measures can be precisely adjusted, and over- or under-supply can be detected early. The Horiba LAQUAtwin NO3-11C provides a precise, fast, and practical solution for this purpose. Typical applications for the Horiba Nitrate Analysis Kit Aquaculture and coral monitoring Aquaristics Horticulture Beverage and food production Laboratories and schools Environmental monitoring Water treatment Water conditioning Frequently asked questions How long is the warranty period for HORIBA pocket testers? The warranty period is two years from delivery for commercial customers. How many measurements can be taken before the sensor needs to be replaced? This varies depending on the application, use and storage of the Horiba tester. As a rule, the sensor should be replaced after one year. How long is the warranty period for replacement sensors for pocket testers? The warranty period is 12 months after delivery for commercial customers. How do you clean the pocket tester? The pocket tester can be rinsed under water. We recommend cleaning with DI water (deionised). Tissue paper is recommended for drying after cleaning. How can the pocket tester be reset to factory settings? (e.g. in the event of an incorrect measurement result) This information can be found in the operating instructions. These can be found in the download area of the shop and on the product. Is calibration necessary before each measurement? Basically, yes. Further information can be found in the operating instructions.
Mobile Analysis Laboratory for Ion Measurements – Versatile Use Compact kit for simultaneous determination of multiple water and environmental parameters The Horiba 4M LAQUAtwin Kit is a mobile laboratory that allows you to determine important ion parameters directly on-site. The case contains pocket testers for measuring sodium, potassium, nitrate, and calcium, as well as for temperature measurement. Each device uses ion-selective electrodes for targeted analysis of small samples and provides fast, reliable results. In addition to the four measurement devices, the kit includes calibration solutions and a wash/spray bottle for sensor cleaning. The sensors can be stored dry without special storage solutions. Compact Multi-Parameter Kit for Flexible On-Site Analyses The set is designed for measurement tasks where multiple ions need to be detected simultaneously, for example when monitoring drinking and process water, performing environmental checks of water bodies, conducting aquaculture analyses, or agricultural research. Thanks to the case, all essential testers including accessories are always on hand and ready for immediate use. The measurement results are available in a short time and are reliable and reproducible – ideal for routine and control measurements in the field. All components are neatly arranged in the case and ready for use at any time. An additional advantage is that the sensors can be stored dry without special storage solutions. Due to its compact design, the kit is particularly suitable for mobile applications where multiple ion parameters need to be determined quickly one after the other or in parallel. Why Multi-Parameter Ion Measurements Are Useful – and a Mobile Kit Is Ideal In many applications, not just a single measurement is important, but the interaction of multiple ion parameters. Sodium, potassium, nitrate, and calcium together influence water quality, biological processes, plant growth, and technical operations. Single measurements in a laboratory are often time-consuming and inflexible. A mobile analysis kit allows simultaneous detection of multiple parameters directly on-site. This allows relationships to be recognized more quickly, decisions to be made more reliably, and measurement campaigns to be carried out more efficiently. The Horiba 4M LAQUAtwin Kit combines these advantages in a compact, user-friendly system. Frequently asked questions How long is the warranty period for HORIBA pocket testers? The warranty period is two years from delivery for commercial customers. How many measurements can be taken before the sensor needs to be replaced? This varies depending on the application, use and storage of the Horiba tester. As a rule, the sensor should be replaced after one year. How long is the warranty period for replacement sensors for pocket testers? The warranty period is 12 months after delivery for commercial customers. How do you clean the pocket tester? The pocket tester can be rinsed under water. We recommend cleaning with DI water (deionised). Tissue paper is recommended for drying after cleaning. How can the pocket tester be reset to factory settings? (e.g. in the event of an incorrect measurement result) This information can be found in the operating instructions. These can be found in the download area of the shop and on the product. Is calibration necessary before each measurement? Basically, yes. Further information can be found in the operating instructions.
Horiba LAQUAtwin Nitrate Ion Tester NO3-11 for Precise On-Site Measurements Handheld tester with 2-point calibration, ideal for water and environmental measurements The Horiba LAQUAtwin Nitrate Ion Tester (NO3-11) is a portable device for direct determination of nitrate ions (NO3) and temperature in liquids and samples. Thanks to the ion-selective electrode and compact design, the tester delivers fast and reliable results. The integrated temperature unit enables temperature-compensated analysis and clearly displays both nitrate and temperature values on the digital LCD display. Mobile Nitrate Ion Tester for Precise On-Site Analyses The integrated temperature measurement enables temperature-compensated analysis and shows both nitrate and temperature values. Only very small sample volumes are required, minimizing sample consumption and increasing efficiency in daily use. The tester can be set up with up to two calibration points, with features such as automatic standard recognition, adjustable calibration values, and multiplication compensation for flexibility. Only minimal sample volumes are needed for each analysis, reducing sample usage and improving efficiency. Why Nitrate Measurement Is Crucial – and a Pocket Tester from Horiba Is Ideal Nitrate measurement plays a central role in agriculture, water management, and environmental monitoring. Elevated nitrate concentrations can affect drinking water quality, stress ecosystems, and contribute to over-fertilization. At the same time, nitrate is an essential nutrient for plants, and targeted control is vital for sustainable agriculture. A mobile nitrate pocket tester enables rapid on-site analysis without time-consuming laboratory tests. This allows early detection of contamination, immediate action, and reliable monitoring of legal limits. The Horiba LAQUAtwin NO3-11 combines this flexibility with high measurement accuracy and easy operation – ideal for routine checks and scientific applications. The tester can be configured with up to two calibration points. Features like automatic standard recognition, adjustable calibration values, and multiplication compensation provide high adaptability to different sample types and measurement conditions. Typical Applications of the Horiba LAQUAtwin Nitrate Ion Tester (NO3-11) Agriculture: To optimize fertilizer use, promote plant growth, and minimize environmental impact, farmers and agronomists use the tester to monitor nitrate levels in soils and irrigation water. Water Quality Management: To maintain nitrate concentrations within safe limits, the NO3-11 is used in water management to check drinking and wastewater quality. Environmental Monitoring: The NO3-11 allows environmental technicians and scientists to quickly analyze nitrate contamination in rivers, lakes, and groundwater, ensuring compliance with environmental standards and identifying pollution sources. Research and Development: The tester is used by scientists in environmental science, hydrology, and soil science to conduct detailed studies of the nitrogen cycle and the effects of nitrates on ecosystems. Frequently asked questions How long is the warranty period for HORIBA pocket testers? The warranty period is two years from delivery for commercial customers. How many measurements can be taken before the sensor needs to be replaced? This varies depending on the application, use and storage of the Horiba tester. As a rule, the sensor should be replaced after one year. How long is the warranty period for replacement sensors for pocket testers? The warranty period is 12 months after delivery for commercial customers. How do you clean the pocket tester? The pocket tester can be rinsed under water. We recommend cleaning with DI water (deionised). Tissue paper is recommended for drying after cleaning. How can the pocket tester be reset to factory settings? (e.g. in the event of an incorrect measurement result) This information can be found in the operating instructions. These can be found in the download area of the shop and on the product. Is calibration necessary before each measurement? Basically, yes. Further information can be found in the operating instructions.
The LAQUAtwin Nitrate Ion Handheld Tester (NO3-11C) included in the analysis kit is pre-set by the factory to the relevant calibration points 30PPM and 300PPM for soil analysis. Manufacturer Part No. 3200689164 | B-742