Map #1 pictures a “Soil Type by Corn Yield Goal” map for the 80 acre field.  Soil types contained within this tract of land provide the basis for other maps, which follow and are used to control the inputs that go into this field. Previous research clearly indicates that different soils have different yield potentials. Because of this factor the optimum profit potential for different soils can be obtained using different input levels for different soil test levels.

 

The different soil types shown on map #1 are represented by different colors, which indicate different corn yield potentials. This soil map is used to develop a much more extensive Soil Test Sites map in order to more aggressively manage the different types of soil found in this field. For example, good management practices suggest it does not make economic sense to fertilize a lower yield potential soil beyond the point it is capable of producing. It is important to note there may be soil test areas of less than an acre or others of more than five areas depending on the various soil types in a specific tract of land.

One of the first maps that we develop after the Soil Type Map is a Soil Fertility Regions Map. An illustration of this map for the 80 acre sample field appears as map #2. Once the soil types have been established for each field, lines in the direction the field is worked are established every 360 feet and transecting lines are developed using the soil type lines in order to create soil fertility regions useful in the application of fertilizer and lime. The 360 foot units of measure matches even multiples of application and planting equipment that we use. This Soil Fertility Regions Map becomes the basis for many of the following application and production maps.

Once soil fertility has been determined through soil samples, questions about pH levels for each region can be addressed. The Soil Fertility Regions pH Map for our sample field is illustrated as Map #3. Utilizing the GSP system, soil samples were taken from 19 separate sites which provided a much more accurate view of soil needs for pH in specific regions of the field. Prior to the use of this management tool, a composite of 2 to 4 samples were taken which gave much less specific information about the needs of the soil in specific regions. Soil sample test results for pH are used in conjunction with a buffer pH map to determine the differing lime needs for specific areas of the filed. These maps are then used with the computer to provide quality control in the variable rate application of lime. In addition, these maps are utilized to optimize the application of particular herbicides that can have yield robbing affects on crops if used on specific areas with high or low pH.