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Spring Canola Nitrogen Rate Calculator Release

Posted by Blythe Howell | October 28, 2021

The Wheat and Small Grains Extension team is happy to announce the development of a new Spring Canola Nitrogen Rate Calculator. The calculator estimates the (nitrogen) N fertilizer rate required to grow a particular yield goal based on the amount of soil N supply. The calculator can be found on the Small Grains Extension website on the tools and calculators page.

How The Calculator Works

The N rate calculator uses estimated yield and soil N supply to determine the amount of N fertilizer required. The estimated yield is used to determine the total amount of N required to achieve a particular yield goal. The soil N supply is determined using the soil organic matter content, the soil mineral N amount from a soil test, and the proceeding crop. The proceeding crop can serve as a N debit that removes N from the system or a N credit that adds to the total supply. Legumes serve as a credit, whereas winter wheat serves as a debit. The soil organic matter content and tillage method are used to calculate N mineralization. Nitrogen mineralization is the process during which soil organic matter is converted to plant-available N. Mineralization depends on the microbes present in the soil and varies depending on soil moisture and temperature. The soil mineral N is the total plant-available nitrogen in the forms of nitrate and ammonium in the soil at the time of the soil test.

The Basis for The Calculator

This calculator was developed based on multiple years of small plot research conducted near Davenport and Pullman, Washington. Small plot research is useful for developing N response curves but cannot account for all the variation in soils and climate within a region. The amount of N required to attain a particular yield goal will vary based on many variables including soil type, location, and year. As such, this calculator should not be used as a guarantee of a particular yield based on a particular rate of N fertilizer, but as a tool to estimate the total N required to achieve a particular yield goal.

Improving The Calculator

This calculator is being released with the goal of improving and customizing it over time. With the goal of improving the calculator, an improvement form has also been developed and is linked below. The goal of the form is to collect data from growers and agronomists to improve the performance of the calculator over time. The calculator requests that growers and agronomists enter soil sampling results, fertilizer information, and yield data that can subsequently be used to test and possibly improve the calculator. Form responses will remain anonymous, unless the contributors choose to enter their email address. The form can be accessed at the Spring Canola Nitrogen Calibration and Correction Data Google Forms page.


For questions or comments, contact Isaac Madsen via email at isaac_madsen@wsu.edu or via phone at (360) 448-9081.

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