Go greener! Secrets of successful lettuce production

Category: Agriculture | Tags:
Salad is always an indispensable part of our menu. With modern cultivation and production in a protected area, lettuce fits perfectly in the cultivation of plants with short vegetation and especially if it is grown in hydroponic or greenhouse production. This avoids the need for crop rotation and we have a fast rotation and a constant supply of the market with these delicious, healthy and crunchy vegetables.
Growing lettuce in protected areas is acceptable in order to protect the environment because it minimizes the pollution, reduces the pesticide use and the amount of water consumed.
Nutrients needed by plants are dosed accurately and precisely, which means that there is no excess nutrients that contribute to eutrophication.
In outdoor lettuce production, soil needs to have, other than fertility, good water-air ratios and easy ability to warm up. Besides that, very important is to maintain a specific pH. Ideal pH value of the soil is from 6.5 to 7.0pH. Lettuce is sensitive to acidity, and especially chlorine. Therefore, when preparing the soil for transplanting and growing lettuce, care should be taken and everything should be prepared in the most ideal ratio from nutrients to pH.


Professional Soil pH Meter
The HI98168 is a rugged, waterproof, portable pH meter that allows for the direct measure of soil pH. This meter is supplied with a specialized pH electrode that has a rugged conical tip for insertion in soil.
Besides being supplied with a unique pH electrode made for soil analysis, the HI98168 has the Hanna’s unique CAL Check™ feature that alerts the user to potential problems during the calibration process. This is a very important since it is likely that the probe will be coated with soil. This coating can easily lead to errors in pH measurement. By comparing previous calibration data to the current calibration, the meter will inform the user, with display prompts, when the probe needs to be cleaned, replaced, or if the pH buffer might be contaminated.
After calibration, the overall probe condition is displayed on screen as a percentage. The probe condition is affected by both the offset and slope characteristics of the pH electrode, both of which can be found in the GLP data including with the readings stored in the meter or transferred to a PC.
  • Quick Connect DIN Connector
  • USB Connection for Data Transfer
  • Dedicated Help Button
  • ±0.002 pH Accuracy
  • Comes with all the necessary solutions and batteries- everything you need to get started measuring right away.
  • Specialized electrode for spot checking the pH of soil and soil slurries.
Of course, the pH value plays an important role in agricultural production. A simple parameter, which can be measured quickly, reliably and cost-effectively, plays an important role in all chemical, physical and microbiological processes in soil, substrate and solutions. Modern agricultural production without regular measurement and monitoring of pH is not conceivable in order to plan the necessary agro-technical interventions and measures.
Table with optimal pH for different plant species:
Vegetable Plants Optimal pH
Brussels Sprout
Corn (Maize)
Early carrot
Early Potato
Egg Plant
Late carrot
Late Potato
Vegetable Plants Optimal pH
String Beans
Sugar beet
Sweet Potato


Soil pH Tester
The HI981030 GroLine soil pH tester is an application specific designed pH tester for the measurement of soil pH. This meter offers many advanced features including the ability to clear any clogging of the reference junction, which results in a longer life than standard pH testers.
  • ±0.05 pH accuracy
  • Comes with all the necessary solutions and batteries- everything you need to get started measuring right away.
  • Specialized electrode for spot checking the pH of soil and soil slurries.
Of course, growing medium also require for successful growth and development that the pH of the soil is balanced and accurate, and that the reaction is as ideal as possible so that the seeds are used to the maximum and the plants germinate quickly. Seedlings grown in a properly maintained cubic substrate quickly come to the stage that they can be transplanted outdoors and have a good start. During the cultivation of seedlings, it is important to measure the state of the nutrient solution several times a day and at different points, ie pH, EC parameters, solution temperature, TDS and other specific parameters.


pH/EC/TDS/Temp meter
HI9814 is a durable, portable pH, conductivity, total dissolved solids and temperature meter for most measurements encountered in hydroponics, aquaponics or general agriculture applications. All operations and settings, are made through only two buttons and the housing is waterproof and rated for IP67 conditions. User-selectable features include selectable TDS factors of 0.5 and 0.7 as well as auto-off after 8 minutes or 60 minutes to prolong battery life.
Another type of salad production is hydroponics, can be projected with or without substrate. This type of production is most often used to grow leafy vegetables, so the benefit is in recycled water, and in decrease of environmental pollution.
By controlling the pH and EC in the recycled waste solution, in addition to saving water and nutrients, the amount of nutrients that will be added and will be used is balanced and it is important to check nutrient composition and residue.


Nutrient Analysis Photometer
HI83325 is a compact, multiparameter photometer for use in the environmental lab or in the field. The meter is one of the most advanced photometers available with a innovative optical design that utilizes a reference detector and focusing lens to eliminate errors from changes in the light source and from imperfections in the glass cuvette. This meter has 9 different programmed methods measuring 8 key plant nutrient water quality parameters and also offers an absorbance measurement mode for performance verification and for users that would like to develop their own concentration versus absorbance curves. Plant nutrient-specific parameters include potassium, calcium, and magnesium. To save valuable laboratory benchtop space, the HI83325 doubles as a professional pH meter with its digital pH/temperature electrode input. Now one meter can be used for both photometric and pH measurements.
By having a targeted quality and quantity, the earnings can rise while reducing input costs.Irrigation water is an important factor to be measured and monitored. Depending on the chemical composition, hardness and pH, the plants will successfully absorb certain nutrients. Especially when growing outdoors and achieving a balance in the nutrient solution and the best possible ratio of water and air capacity, it is necessary to adapt the nutrient solution as ideally as possible to the requirements of the plants that are grown.
Analysis of water basic chemical and physical parameters is recommended. Higher amounts of salt or high pH are most common in waters, and such waters are not suitable for irrigation because they cause secondary salinization.
Of course in hydroponic cultivation it is also important to measure the oxygen concentration in the solution (D.O.). Without dissolved oxygen in the nutrient solution the plantation would perish and profit would be lost.


Portable Optical DO (opdo) meter
HI98198 uses a luminescent optical method for the measurement of dissolved oxygen in water and wastewater.
This professional, waterproof meter complies with IP67 standards and measures:
  • DO
  • barometric
  • pressure
  • BOD
  • temperature

The HI98198 is supplied complete with all accessories including probe, smartcap sensor with built in RFID, and a rugged carrying case.


HI98198 Dissolved Oxygen Meter has many advantages over other Galvanic and Polarographic Dissolved Oxygen Meters. This meter uses HI764113 Rugged Optical Dissolved Oxygen Probe for Dissolved Oxygen measurement which has following benefits:
  • No membranes
  • No electrolytes
  • No oxygen consumption
  • No flow dependence or minimum flow rate
  • Fast and stable readings
  • Minimal maintenance


Portable pH/EC/DO Meter
with Bluetooth
Functional and accurate, this meter is capable of testing 12 different water quality parameters using pH, EC, and optical DO sensors. Transfer data to a smart device for review or sharing with the integrated Bluetooth connection and Hanna Lab App. Device is waterproof ( meter rated IP67, probe rated IP68). It has automatic interval logging of up to 45,000 samples or log-on-demand. HI98494 is perfect for environmental and industrial professionals.
Water used in hydroponic cultivation should be monitored, because in addition to the lack of water at high temperatures, photosynthesis is reduced and thus the associated reduction in yield. The temperature of the water in the hydroponics should be close to the temperature of the greenhouse. Water with lower temperatures can cause a shock to plants, so it is necessary to always have a sufficient supply of water to always, with ideally tempered water, refresh the plantation.


Checktemp Dip
Digital Thermometer
The Checktemp Dip Digital Thermometer – HI98539 is a high-accuracy thermometer connected to a weighted, stainless steel probe by a 3 m (9.9’) flexible, silicone cable. The probe incorporates an NTC thermistor sensor, providing an extremely accurate temperature measurement that can satisfy your HACCP requirements.
  • CAL Check
  • Selectable °C/°F readout
  • AISI 316 Stainless Steel Probe
Farmers which grow lettuce outdoors, most often in spring and summer, have problems with EC values where the EC values can reach critical points. The research has shown that values above 1 -1.5mS is already critical. As farmers fertilize their crops more or less similarly to mineral fertilizers, whether land reclamation and corrective foliar, EC change must be monitored to know if it needs to be corrected with irrigation.
Even more problems are posed by autumn for winter planting in the open, where we have a high EC following the EC parameter and because of it growth retardation because nutrients are not consumed and slower growth and development of heads occurs. pH and EC measurements are essential analytical methods in greenhouse production.
Hanna Tip:

When measuring EC in soil & soilless medium, take measurements right next to the plants as well as further away. Moisture, nutrients, and pH can vary greatly across a planted area. This means a little more work, but you will appreciate being able to get results that better represent your planting area.


Direct Soil EC Tester Soil Test™
The Soil Test™ Direct Soil EC Tester – HI98331 is a rugged and reliable pocket-sized tester that offers quick and accurate readings. The Soil Test™ Direct Soil EC Tester – HI98331 features a stainless steel penetration probe for direct measurement of conductivity in soils. With a compact size, single button operation, and automatic calibration, Soil Test is an excellent choice for taking direct conductivity measurements in soil.
automatisation & control
In lettuce production it is essential to establish the frequency of watering so that the plant does not undergo root suffocation and through water stress. The lettuce plant has a very delicate root system which doesn’t tolerate high moisture very well. If ratios of applied irrigation cycles vs. nutrients cycles are not carried correctly, huge losses in yield could occur.
With proper irrigation
the quality and quantity of lettuce
can be significantly enhanced.
Correct irrigation
Is not a simple process: the quantity of water must be sufficient for lettuce plants, and if not, photosynthesis and overall growth is impeded. However, if the amount of water is more than required, plant growth may become excessive, producing a tall, softer and/or damaged product.
We design and manufacture a complete, ready-to-install,
ferti-irrigation system for our customers.
At first, we collect the information and requests of the agronomist to create a system that corresponds to the actual needs of the customer. Afterward, we analyze the existing infrastructures to be able to interface our systems with the fixture already installed.
Finally, we produce the customized system and proceed with the installation, commissioning, and training of the personnel in charge.
Our ferti-irrigation systems have multiple applications:
  • Outdoor farming
  • Indoor (soil) farming
  • Hydroponics
  • Aeroponic
Our fertigation system integrates Hanna Instruments process equipment with high-quality industrial products to create two types of systems:
  • Direct injection of nutrients
  • Mixing tank
Fertigation Controller
The Fertigation Controller can control the quantity of irrigation water based on time or volume. Different sectors can be irrigated at different times during the day with different water quantities.
With the Fertigation Controller, each irrigation program provides control of pH and conductivity. When necessary, a specific program performs a pH correction by the introduction of an acid or base into the irrigation water. pH control is based on multiple sensor input and a specific set point, while conductivity control is directly related to the level of fertilization.
When the Fertigation Controller commands the addition of 1 to multiple fertilizers in the irrigation stream, conductivity sensors continually monitor the conductivity of the stream and the overall amount of fertilization is maintained based on a specified set point (limit). The Fertigation Controller can command the addition of multiple (1 to 4) fertilizers to irrigation water. The percentage of each fertilizer is set up by the user and controlled by a specific program based on the conductivity set point.
If a pH or conductivity control problem arises, the program generates an alarm to inform the user. All operations of both control processes are stored in the memory.
The Fertigation controller performs all necessary operations, monitoring, control of irrigation, and fertilization processes. These operations are conducted continuously throughout the day, month and year.
To use and manage the system properly, all the necessary control values must be set (setup mode). During monitoring operations (consulting mode) the user can obtain information about how the system and irrigation process are functioning. Furthermore, the history of all operations for the current and previous days can be accessed.