During harvest, Kurt Nolte will utilize a radio frequency identification system (RFID) he helped develop for food safety and traceability in vegetables. RFID will allow Nolte to determine precise yields in the field and then tied the information back to the actual P applications.

The UA team will assess the season-long data to determine the impact of the site specific P applications.

The bottom line, Sanchez says - “A practice must be economically viable before a grower will use a new practice,” Sanchez said. “My hypothetical calculations suggest that variable phosphorus applications can economically benefit the grower.”

Next year, the program will be tweaked and then expanded in the fall on additional farms. In 2015, the program would be fine tuned further with Extension outreach to share the results with the vegetable industry.

Once the project is completed, the findings would be turned over to the private sector to further tweak the program and possibly make it commercially available to the vegetable industry.

Site-specific fertilization is currently used in the Midwest in agronomic crops, including corn and soybeans. While growers there have not seen much of a yield benefit, Sanchez says consistent fertilizer savings alone have increased economic returns to growers.

“In lettuce, which is sensitive to phosphorus, I believe we’ll see an increase in yield in addition to the cost savings from reduced phosphorus use,” Sanchez said.

Andrade added, “I think the variable rate system could be economically viable to growers since it is an un-lockable extension of auto-steer technology which many growers already use.”

Not only are cost savings to the grower important. Fewer P applications could have a broader societal and environmental impact. Unused P by crops or tied up in the soil can be transported downstream into bodies of water.

Sanchez summarized, “The need to improve P use efficiency in agricultural production systems is urgent, especially in high value crops which receive large amounts of P fertilizer for optimal yield and quality.”

This makes site specific P application in vegetables even more important.


More great reads from Western Farm Press:

California, Arizona LGMAs change food safety metrics

New biotech alfalfas aim to improve feeding efficiency

Alfalfa yields increased through drip irrigation