Ag News
Ag News

Use Response-to Scores to Shape Variable-Rate RXs

  • Mar 30, 2018
Use Response-to Scores to Shape Variable-Rate RXs
Are you and your trusted advisor starting to create variable-rate prescriptions for the hybrids you purchased to plant this spring? Use scores from the Answer Plot® program to determine your hybrids’ response to population, response to nitrogen and response to fungicide to better target your input dollars and optimize your ROI potential.

Use the tools
By this time, perhaps you and your agronomist have used the R7® Tool Top 10 function to identify the best-performing hybrids for each field based on soil type. Now you can go a step further by tapping into the Corn Characterization Charts (CHT Tool). This tool uses Answer Plot® program data to compare seed from various companies to determine how they are projected to perform on fields just like yours. Categories for comparison include response to crop rotation, plant population, fungicide and nitrogen management. These comparisons allow you to manage and capitalize on field variability.

Know the score Response-to scores, accessed through the CHT Tool, can help you determine how a particular hybrid will perform under different management practices. Each hybrid is replicated multiple times at nearly 200 Answer Plot® locations across the United States before it is assigned a response-to score.

Response to Population (RTP)
A hybrid with a high RTP rating typically responds in yield as plant populations increase. These hybrids tend to have what the industry refers to as a “fixed” ear type, though this is not always the case. The ability of a hybrid to respond to increased populations allows you and your agronomist to take advantage of higher-management zones or higher-yielding areas of the field to push yield potential.

Conversely, a hybrid with a low RTP rating will give you roughly the same proportional yield at a low or high plant population. When using these hybrids, your agronomist may recommend lowering your existing population to allocate resources to other expenditures. These hybrids can also be good choices to use on lower-yielding areas of the field, as the ability to increase root size allows it to extract additional water and nutrients from the soil that a high RTP hybrid cannot.         
Response to Nitrogen (RTN)
Nitrogen is one of the most expensive inputs a grower must manage during the growing season, and it’s also one of the biggest factors that influence yield as determined by Answer Plot® data. Depending on the response-to score of a hybrid, you may want to consider a split application of N, include a N stabilizer, or increase the rate of N on hybrids with a high response to N. Those hybrids with a low or medium response to N may be for the acre that is not as highly managed.
Soil type and nutrient-holding capacity are also key factors to consider with RTN scores. As nutrient-holding capacity decreases, the ability for a high-RTN hybrid to be successful also decreases.     
Response to Fungicide (RTF)
A high RTF score means that a hybrid has the potential to provide an economic gain in bushels if a fungicide is used. If you have planted a hybrid with a high RTF score, that hybrid should take precedence over other hybrids you have in the field when you apply fungicide. Hybrids with medium or low RTF scores should be sprayed last for a plant health benefit. However, remember to scout your fields for disease development during the growing season. You may have to spray your crop for diseases independent of its RTF rating.
Cut to the chase
It takes about two years to determine how to manage a hybrid well. Response-to scores do a lot of that legwork for you, allowing you to manage your hybrids to their highest potential so you can derive optimal ROI and yield potential. Talk with your trusted advisor now about how to best leverage response-to scores this season.