To download the Ontario Nitrogen Calculator (ONC) CLICK HERE
Crop planning by customer by farm by field by crop by product continues on with even more urgency as spring-like weather in late February and early March lingers. One of the input areas of interest with challenging crop prices is Nitrogen on corn. Determination of the “right” rate of nitrogen continues to be somewhat elusive as many factors compound the choosing of the right rate. Is the right rate something that is realistic? At some point we need a “number” to set up an applicator to apply the targeted rate of nitrogen. The reality is most decisions we make in farming are from a systematic process of trade offs with consideration given for risks associated with each decision step. Add in field variability the complexity increases.
One of the tools we can use to understand the complexity of making a nitrogen recommendation is the Ontario Nitrogen Calculator (ONC). The calculator ask for input on soil texture, soil organic matter, yield goal, price of corn, price of nitrogen, any other nitrogen sources and previous crop. It is an interactive spread sheet so you can enter different scenarios to see how that impacts on the nitrogen rate.
It allows for a pre-sidedress nitrate soil test to be used prior to side-dressing UAN as final check in adjusting N rates which overrides the preplant and side-dress application rates calculated previously. In this example a PSNT test of 11 ppm taken in early June adjusts the N recommendation to 180 lbs. of N. The spread sheet also provides for an interpretation of an ear leaf tissue sample.
Once you have the spread sheet filled in it is easy to change the price of corn and see how that changes the nitrogen recommendation. Under this scenario dropping the price of corn from $5.75 to $4.75 only drops the nitrogen rate by 12 Lbs. of actual N per acre. Changing soil texture from loamy sand to heavy clay increases N recommendation to 214 lbs. of actual N. Changing soil organic matter from 3% to 5% decreases N recommendation by 24 lbs. of N. Changing the previous crop from corn to red clover ploughed down decreases the N recommendation by 73 lbs. to 126 lbs. of actual N.
What’s the right rate of nitrogen? It is situationally specific.
Download the spread sheet and contact your AGRIS Crop Specialists to learn more on managing nitrogen application risk. Including the use of nitrogen stabilizers to further protect the nitrogen investment and reduce any environmental risk of N loss.