High-Tech Tags

Mobile RFID and bar code reader

Radio Frequency Identification (RFID) technology has been around for decades. A true ancestor of the modern RFID tags could be traced back to 1973 as a system developed in New York to automate toll collection. In simple terms, RFID is an identification technology for tracking and managing assets and products. While similar to the more familiar bar code system, it offers a major advantage over bar coding in that the reader does not need direct line of sight to read the tag.

A typical RFID system consists of an RFID tag or "transponder," which is assigned a unique code, and a reader that can read this tag. The tag comes with built in memory that can store information about the goods or objects to which it is attached. The reader recognizes the tag, which helps in tracking and identifying assets and products.

Types of tags
RFID tags can be classified as active or passive depending on the source of power they use for transmitting radio waves. Active tags have their own power source and usually have more memory and range when compared to passive tags, which use the induced energy from transmitted waves of the RFID reader. On the downside, active tags are more expensive when compared to their passive counterparts and need replacement of batteries over specific intervals of time.

RFID tags can also be classified based on the transmission frequency:

• Low frequency (LF) tags (125 - 134.2 KHz)
• High frequency (HF) tags (13.56 MHz)
• Ultra high frequency(UHF) tags (868 - 956 MHz)

LF and HF tags are widely used for smartcard applications while UHF tags are used more frequently in supply-chain management systems. There are strengths and weaknesses to each of these types of tags. For example, the effective transmission range of signals used in LF tags is shorter (reading range of inches) compared to signals used in UHF tags (reading range of several feet), however, UHF tags are more affected by obstacles such as the metal in shipping racks, and water, both of which result in poor readability of UHF tags.
 

RFID in nurseries
To date, RFID has been used predominantly in asset tracking, but its usefulness spans a plethora of applications in agriculture, finance, manufacturing and transportation.The nursery and greenhouse industry can use RFID to manage plants from the propagation stage to a finished plant. At the seedling or plug stage, flats containing plants can be tagged and tracked using the flat information. One advantage of RFID is that information such as the plant name, growing location, chemical applications and cultural conditions can all be stored in the RFID tag. When small plants are moved from flats to individual containers, new tags are required that retain the previous history. In a typical nursery or greenhouse, RFID tags could be read using a handheld RFID reader. The RFID reader can be easily mounted on a user's wrist and the tags can be read at the click of a button. These readers also allow information stored in the tags to be read immediately and then transmitted to a remote database. RFID readers can also be "fixed stations." In this scenario, flats or entire benches can pass near stations and inventory or crop information collected as the product passes by.

Although there are a few examples of RFID adoption in the green industry, research is continuing to explore practical applications and tp fomd solutions to overcome associated challenges. Knox Nursery in Winter Garden, Fla., has successfully implemented UHF tags into its greenhouse operation to improve business efficiency since 2008. The RFID and bar code tag is directly attached to plug flats. Flats could be monitored at any stage of production or during shipping. It is fascinating to realize that flats can be read through a sealed cardboard shipping box. As a pioneer in this field, Knox Nursery found it challenging in the beginning to identify appropriate RFID tags and develop a system for use in a plant production environment. Today, with experience under its belt, the company is offering other growers a management solution called Growers Own. Knox found that adopting this system has 1) not interfered with workflow nor increased labor to perform scans, 2) reduced disposal and increased inventory turns, 3) increased sales due to better forecasting and 4) reduced availability reporting from three days to two hours.

HisTrees.net, a Canadian company, is marketing a system for tracking trees using RFID technology. Using UHF tags and a metal cable-loop, they have found this to be a very good system for monitoring and storing information on trees in either nursery or landscape settings. RFID tags are also being used in Holland to track cut-flower movement from growers, through the flower auction and then to the final customer. Falken Secure Networks has indicated it is interested in developing RFID systems for growers.

As an alternative to attaching RFID tags to a limb or trunk, one group of researchers in Italy suggests that in some cases RFID microchips could be imbedded inside the stem thus eliminating the issue of lost tags. Using roses as a test plant, the researchers demonstrated that implanting a microchip in a rose cane did not cause xylem necrosis in canes, but wilt of the lateral shoot and negative impacts on growth were observed in smaller diameter canes compared to control plants.

Another group of researchers in Italy is engaged in evaluating a RFID system using three frequencies (LF, HF, UHF) and different antenna configurations to track potted plants from the nursery to distribution.

The primary challenge in implementing RFID in greenhouse or nursery applications is matching the appropriate tag with the production system. If tracking plants from a distance (more than a few inches) is important, then UHF tags would be the best choice. Since UHF tags are strongly influenced by metals and liquids, precautions need to be taken to avoid these situations. If distance is not a criterion for tracking plants, then both LF and HF tags would be the best bet as they operate well irrespective of the presence of metals and liquids. Other challenges to adopting RFID in the green industry include 1) high cost to deploy (although this is dropping rapidly like other technologies), 2) tags and reader interfaces being proprietary, and 3) delay in RFID standardization. Research is underway to overcome some of these technical challenges for realizing full potential of RFID technology by the green industry.

Dharmendra Saraswat is assistant professor, Bio and Agricultural Engineering, dsaraswat@uaex.edu; and Jim Robbins is extension horticultural specialist, University of Arkansas, jrobbins@uaex.edu.