Three Fresh Ways to Analyze Your Crop

July 18, 2014 06:59 AM
Three Fresh Ways to Analyze Your Crop

Life in the computer age means that new high-tech ways to analyze your crop are constantly being devised. Here are three fresh solutions that allow you to get a faster, more accurate handle on what your crop needs.

1. Leaf area index (LAI) measurement. LAI, which is a ratio of crop canopy to ground cover, can an under-appreciated indicator of stress in a canopy, according to Rod Madsen, LI-COR product manager.

"It gives a really good indication of how much leaf area is being used for photosynthesis, which really drives production," he says. "Look at soybean during flowering stage, for instance. An open canopy at that stage is just wasting energy."

Determining LAI can help farmers identify some different management practices they should deploy on areas where plants are stressed and not closing canopy as quickly. LI-COR has developed a plant canopy analyzer to take accurate LAI samples without resorting to crop description collection techniques, Madsen says.

Madsen says LAI hasn’t been discussed much but adds that farmers are typically interested in new ways to look at their crops.

"Farmers seem more in tune with technology today," he says. "They want to understand not just their production, but also get into the details about why small sections of a given field aren’t producing and learn how to manage them differently."

2. Sap analysis. While tissue analysis shows what nutrients the plant has already used, sap analysis shows what it still has in reserve, says Michelle Gregg, program director of Crop Health Laboratories.

"Tissue sampling is sort of like a post-mortem test," she says. "Sap analysis, however, carries the same diagnostic value of a blood sample. The test provides a screenshot of nutrient in the sap before it is metabolized by plant sells."

Because of this, farmers can anticipate crop needs and make fertility inputs before the plant even expresses deficiency symptoms, Gregg says. The tool has become increasingly popular in orchards, although she says Crop Health Laboratories is able to sample sap from any row crop.

"Sap analysis has become the key component of my nutrient management program," says Mike Omeg, an orchard grower in Washington. "Using this tool, I am able to adjust the contents of nutrient applications in real-time."

3. DGCI analysis. You’ve heard of NDVI, but what about DGCI? That stands for "dark green color index." Jacob Madden, director of marketing for Spectrum Technologies, explains.

"The whole idea is to measure the subtle difference in greenness that your eyes can’t detect," he says.

Historically, consultants have used a $2,000 gadget called a SPAD meter to get similar readings. Thanks to DGCI, Spectrum was able to develop an app for iPhone and iPad devices that can take readings that correlate to SPAD readings for about a tenth of the cost. The FieldScout GreenIndex+ app costs $99.99, and users must purchase an additional color board for $49.

The board is colored green and yellow (specific color standards that help balance out relative cloudy and sunny field conditions), bright pink (as a contrast tool) and gray (for white balancing smartphone cameras). Users place a corn leaf on the board and take a photo with their iPhone or iPad. Do this 20 or 30 times, and the app has enough information to calculate the average DGCI across the field. Iowa State University and Penn State University both have methods of calculating nitrogen needs based on SPAD readings.

"By utilizing modified versions of industry-accepted university models, the app provides a good guideline for how much N to put down," Madden says.

Once a user gets comfortable with using it, he or she can collect readings in a matter of minutes, he adds.

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