By Andi Anderson
A new study has found that management zone maps are not very reliable in predicting which parts of a cornfield will respond best to higher rates of seeding or nitrogen application. The study found that weather conditions are the most important factor in determining crop responses to inputs, and that these responses can vary significantly from year to year.
The study, which was published in the Agronomy Journal, was conducted by researchers at the University of Illinois Urbana-Champaign. The researchers conducted trials on seven typical non-irrigated Illinois corn production sites over a six-year period. Each site was subdivided into hundreds of plots, and each plot received a randomized rate of corn seeding and nitrogen application. The researchers also measured the soil composition, topography, and other site-specific landscape features of each plot. All other variables except weather were standardized across the fields.
By measuring the yield of each plot during harvest over multiple years, the researchers determined which plots were the most responsive to inputs each year. They then used an advanced algorithm to determine which factors best predicted whether higher nitrogen application or a higher seeding rate would improve yields.
The researchers found that weather variables are the most important factor in determining the spatial patterns of response to the nitrogen rate or the seed rate, followed by landscape and soil attributes. They also found that the responses vary from year to year depending on the weather effects.
This means that a plot that responds well to a higher nitrogen rate one year might not respond so well the next time it is planted in corn. This makes management zone mapping an unreliable predictor of crop responses to inputs.
The researchers believe that more multiyear data and better on-site sensor and analysis tools can eventually improve the predictive ability of management zone mapping. However, their findings suggest that management zone maps are currently of limited use to corn growers.
Implications for corn growers
Corn growers should be cautious in using management zone maps to make decisions about input application. Weather conditions are the most important factor in determining crop responses to inputs, and these responses can vary significantly from year to year. This means that a management zone map that is accurate one year may not be accurate the next year.
Corn growers should instead focus on using other methods to manage their inputs, such as variable rate application (VRA). VRA allows growers to apply inputs at different rates to different parts of a field, based on real-time data about soil conditions and crop health. VRA can be a more effective way to manage inputs than management zone mapping, because it takes into account the current state of the field, rather than relying on data from previous years.
The study's findings suggest that management zone maps are not a reliable tool for predicting crop responses to inputs. Weather conditions are the most important factor in determining crop responses, and these responses can vary significantly from year to year. Corn growers should instead focus on using other methods to manage their inputs, such as variable rate application.
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Categories: Illinois, Crops, Corn