New sprayer-mounted remote-sensing tools could help cotton growers reduce costs for defoliants and plant growth regulators by a third and boost lint yields about 15% with a total variable-rate system, says Tim Sharp, precision agriculture program chair at Oklahoma State University-Okmulgee.

Sharp says sprayer-mounted remote-sensing systems offer the same ability as aerial sensing systems to detect differences in crop growth patterns. These differences are then used to drive variable-rate input applications.

But unlike aerial approaches, machine-mounted sensors aren't affected by cloud cover. And they do an excellent job of geo-referencing the images they create, which can be a challenge for aerial systems.

Except for logistical differences surrounding clouds and geo-referencing, research shows that aerial and machine-mounted sensors produce similar images for variable-rate applications, he says.

Sharp says that careful use of remote-sensing systems offers the potential of dramatically reducing cotton input costs and increasing lint yield.

“In general, we have cut total crop input costs by about 30% and increased our yields by about 15%,” he says. “This is a big payoff for precision agriculture.”

Until more research is completed on how early season remote-sensing images correlate to late-season crop development, Sharp advises growers to base variable-rate applications on remote-sensing imagery from late in the growing season, just before defoliation.