This is the second of a four part series on Nutrient Management sponsored by FS/GROWMARK

Two years ago, GROWMARK started a pilot program in the state of Illinois called N-Watch to help farmers determine the concentration, form and location of plant-available nitrogen. It started with about 45 sites in Illinois and it has grown quite a bit since then.

“Right now we’re a little under 400 sites,” said Dr. Howard Brown, GROWMARK director of nutrient management and environmental stewardship. “We go from western Iowa, all the way up to the southern part of Ontario, down into Ohio and Indiana. So, we’re really excited about where we’re currently at with the program and there’s a lot of interest growing with farmers who want a new management tool to monitor the dynamics of plant available nitrogen.”

The objectives of the program are to quantify the form of available, soil-applied nitrogen (N), where it is located, and what happens to the concentration of available N over time in the upper 0-12 and 12-24 inch profiles of the soil. “Basically we break it into two different types of sampling,” Brown explains. “One we refer to as the inventory and the other is the tracking.”

Inventory sampling takes a look at a cross section of a field to measure plant available nitrogen every three inches for 30 inches. “Starting after harvest, this allows us to inventory residual nitrogen as we’re moving into the time of year when there will be no crop cover,” said Brown. The program then tracks the nitrogen by taking composite samples every 2-4 weeks until it freezes, and then in the spring to see if the residual nitrogen is still there.

Listen to Howard explain more about this program and its role in nutrient management on the farm. Interview with Howard Brown, GROWMARK

As this series continues, we will hear about the impact of N use beyond farm economics, and developing nutrient management plans. Read the first post in the series on Illinois’ nutrient loss reduction strategy here.

Nutrient Management Series

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