Irrigation Control

Along with complete climate control, Argus Systems have fully integrated irrigation and nutrient management capabilities. Our irrigation and nutrient management controls are not simply "token" programs. They are among the most complete and sophisticated programs available in the industry, in most cases matching or exceeding the capabilities of even the best European systems. Flexibility and an "open" system are two of the key factors that set Argus apart. Argus can control virtually any type of pump, valve, or other equipment. We can assist in the design of virtually any irrigation and nutrient system, including all types of "site-built" systems.

The Argus system has also been used to provide all measurement and control functions for many different commercially available nutrient injection and mixing systems.

Irrigation System Capacity Management

An irrigation system is defined as an integrated system that includes one or more sources of water or fertilizer solution, a main pump(s), distribution piping around the nursery, irrigation valves and final irrigation water delivery systems. The Argus System can accommodate:

• Four different irrigation feed sources per irrigation system
• Wells, tanks, ponds, and water mains controlled by pumps and/or valves
• Water level/volume management in tanks and ponds
• Output source and irrigation valve coordination
• Up to 160 independent irrigation zone or valve sets per irrigation system. Output capacity and other settings can be made for each valve.

Irrigation Decision Making

• Meet water demand.
• Fertilizer delivery to the crop.
• Flush salt build-up from the soil.
• Cool the soil surface to prevent high temperature damage to tender crops (seedlings).
• Humidify the air and reduce crop wilting and stress.
• Provide some frost protection on outdoor crops in spring and fall.
• Bring the crop to a uniform moisture level before packing and shipping.

• Manual operation

• Time schedules

  	Time of day
  	Two-week calendar

• Sensor accumulation values

  	Light sensor input
  	Other sensor input

• Combination time-sensor values
• Water starts based on an accumulation of sensor measurements or time-interval values. Watering response can vary with time of day and can automatically track a user-defined schedule as the crop grows from seedling to market.
• Control equations using measurements from, for example:

  	Soil tensiometers
  	Weight scales
  	Start-tray irrigation sensors
  	Thermometers (typically for frost and heat protection)

• Specific crop models

  For example, evapotranspiration models that use temperature, light, relative humidity, vapor-pressure deficit (VPD), and other sensor- and sensor-derived measurements as inputs. Once a model is developed for a particular crop and greenhouse, control settings are automatically adjusted to match the changing water requirements over the lifetime of a crop.

Water Scheduling and Capacity Management

Argus separates water decision making (when to water) from the actual delivery of water to the crop (irrigation system capacity management). This frees the grower from having to worry about capacity and feed management limitations of the irrigation system when making watering decisions. The Argus Control System will automatically manage the irrigation-system resources to best meet the requirements of any irrigation zones that need water. The control system maximizes efficient use of the irrigation system while protecting against overloading. If too many zones request water at the same time, the system will schedule them and service them as soon as water supply is available.

Some examples of different types of control and delivery strategies that can be used:

Two priority levels for each valve allows the irrigation system to interrupt water delivery to low priority crops and direct the water to crops that demand more immediate service when water supplies are limited.

• Irrigation pulsing delivers water at a rate that is faster than the growing media is capable of absorbing. This can be more of a problem when the growing media is dry. Normal watering will result in excessive waste and run-off. ‘Pulse’ watering can be used to divide the required watering into a number of shorter pulses with a delay time between each pulse to allow water absorption to occur.
• Recirculating systems

  	Ebb & flood Systems Table & bench systems Floor systems Separate and variable fill, drain, hold times for each zone.
  	Trough & nutrient-film-technique (NFT) systems Hydroponic media (rock wool, pellet, cocoa peat etc.)

• Non-recirculating systems

  	Sprinklers
  	Drip tubes
  	Misting