|
| The two itmes that come to mind first is the yield goal and the soil organic matter (SOM) levels, and not just the top 6 or 8 inches. If you are interested in variable rate N application I assume you have yield differences that would support this application. Once the yield goal has been established for each one of the detailed soil zones the next question is what is the SOM levels of each soil zone. Soils that have higher SOMlevels can produce a bushel of corn with less N than soils with organic matter levels. SOM typically has a C:N ratio of 12:1. Utilizing that information a soil with 4 % SOM will have approximatley 6600 lbs of N in the top 6 inches in an acre. Obviously not all the N is available, but during the breakdown of the organic matter during next years corn crop a percentage of that N will become available. Utilizing the same math a soil with 2 % SOM will have approximatley 3300 lbs of N. A soil with 4 % SOM will have twice as much N available to the plant as a soil with 2 % SOM. Once you understand the SOM variability within a field, you can start to fine tune the N application, and thus produce a bushel of corn with less than 1 lb of N.
Jim | |
|
Variable rate N
