Pinpoint Solutions for Yield Variances

  • Oct 19, 2015
Pinpoint Solutions for Yield Variances
Throughout harvest, it’s not unusual to see yield variations between different parts of each field. While some areas may typically deliver 200 bushels per acre, other spots might yield 40 bushels per acre less. When this happens, crops on the higher-yielding area are removing considerably more fertility from the soil than those in the lower-yielding zones.
If you fertilize fields at a single flat rate , you end up over-fertilizing areas with low yield potential and under-fertilizing areas with high-yield potential, possibly diminishing yield on the acres with your highest financial potential.
Using variable-rate fertilizer applications that correspond to the yield potential in each part of the field allows you to balance your fertility load across the field without increasing the overall fertilization amount. This helps to optimize yield potential across the field and maximize the return on your crop nutrient investment.
There are a few approaches that growers consistently use to determine what the correct variable rate fertilizer program should be for their fields. Over the past 15 years, grid soil sampling has become the most widely accepted form of analyzing fertility levels across a field. The grid sampling process is simple: a grid of data points is laid across the field and independent samples are taken within each grid to see how fertility varies from point to point. This allows you to better see which areas are higher fertility than others. The fertility data received from grid soil sampling is then used to create variable-rate fertility application plans.
In recent years, many growers are beginning to investigate the use of stable yield zones to drive soil sampling, rather than only grids. After identifying good quality zones that represent the different yield environments across a field, growers may then either create one sample per zone or take multiple samples per yield zone. By using spatially derived yield zones to drive soil sampling, a farmer is more likely to actually test areas of the field that are similar together, rather than forcing variability with square grids across the field.
Farmers have found large success using both approaches to variable rate fertility management. Some are even starting to combine the technologies by setting variable yield goals for each zone, instead of setting yield goals across a whole field. Using the R7® Tool, your agronomist can place the field’s yield zone map on top of the grid soil sample data. This combination will help you identify fertility variances, determine appropriate yield goals for each zone and set fertilization rates to support those goals.