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Question: What is the deciding factor in varying the rate of nitrogen? Is it relative to CEC?
Answer: There are multiple factors that have to be put into play. Are you dealing with a high-yield or low-yield environment (both of which can be in a single field)? What is the plant density--are we pushing for high yields? What is the soil’s ability to supply nitrogen?
Traditionally that is a factor dealing with organic matter CEC. The healthier the soil, the more nitrogen it usually supplies. But, it can also depend on field history such as whether it’s been in corn-on-corn, or if manure has been applied to it. One of the things we’re looking at is testing for organic nitrogen followed up with nitrate testing, trying to predict high, medium or low mineralization rates.
The last thing we need to tie into this is the potential for nitrogen loss through nitrification or leeching. An example of this would be a high-yield environment with the ability to supply sufficient nitrogen that it would allow us to reduce our input of nitrogen. Yet that environment could be a high-risk area due to drainage, or, under wet conditions the nitrogen could be lost and we’d have to rescue those areas with more nitrogen.
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