▶ Managing Nitrogen in Potato and Vegetable Crops

0:05
Hello everyone.

0:06
My name is Guolong Liang

0:07
I’m an Ag Water Outreach specialist within the UW Madison Division of Extension.

0:12
I work in the Central Sands area of our state, mostly focusing on commercial vegetable production and agricultural water quality issues.

0:20
And I’m Dan Marzu.

0:21
I’m with the Nutrient and Pest Management Program.

0:25
I’m an outreach specialist serving North Central Wisconsin and I deal primarily with nutrient management with farmers.

0:32
So Guolong

0:33
We’re sitting in the middle of a, I’m assuming this is a cover crop field that would eventually go into some sort of vegetable.

0:40
So as we’re looking at this and you know, farmers are across the road here planting already, what kind of nutrients are farmers, are potato and vegetable farmers concerned about?

0:51
Absolutely.

0:52
So for potato and vegetables, it’s important to have your nutrients checked every year, right?

0:58
And we’re talking major ones, nitrogen, potassium and phosphorus.

1:02
Today we’re going to spend most of our time talking about nitrogen because as we’re here, joining you here from Plover, Wisconsin in the heart of Central Sands as, as the name indicated, we’re standing on top of sandy soil.

1:18
And what that means is that it gives us great flexibility to farm different vegetables on top of this ground.

1:26
However, it also presents a lot of vulnerability when it comes to nutrient loss, right?

1:31
And today we’re going to spend a little bit time talking about and thinking about nitrate.

1:36
Leaching nitrate as the form of nitrogen loss that’s going down into the soil profile, into the groundwater when a heavy rain pours is really an important process for our farmers to be thinking about because it affects the community, effects our local ecosystem and it affects our human health.

1:57
So yeah, today we’ll spend a little time thinking about that dynamic and talk about what farmers can do.

2:04
OK, So well, you led me right into my next question is so you’re more concerned about, you’re concerned about nitrogen here.

2:12
So what can farmers do, particularly potato and vegetable farmers or basically any farmer do to help reduce those nitrogen losses off of their fields?

2:20
Absolutely.

2:22
From agronomy 101, right?

2:24
Everybody talks about the 4R right time, right rate, right placement as well as right form.

2:32
I think when it comes to nitrate leaching, we need to think deeper and harder about the right rate.

2:37
To me, that’s the big R that we that we need to focus on when it comes to leaching and nitrogen loss.

2:45
So finding the optimized rate for whatever crop you’re growing, sweet corn, potato, field corn, especially the ones that require a lot of nitrogen to have a decent yield and to sustain that farm profitability.

3:00
Those are the ones that we need to pay extra attention to, to see if we can cut 10 to 15% or even more from our current program without losing yield, depending on what variety we’re growing, of course.

3:14
But that decrease in nitrogen application overall will do a great number when it comes to reducing nitrogen leaching into our groundwater.

3:25
So that’s one of the practices that I would really encourage people to start trying on a small part of their fields and the other part, if you’re feeling experimental and everybody grows cover crops in Central sands.

3:43
But in order to push it to the next level when it comes to reducing nutrient losses, I think we need to think about how good are we when it comes to the cover crop biomass, right?

3:54
What stage of the cover crop are we looking at right now when we are terminating it?

4:00
What is the carbon to nitrogen ratio when we’re terminating it?

4:04
And how much of that nitrogen within the cover crop can we give credit to, to the falling crop because we’re working with the rotation here, right?

4:13
Potatoes, sweet corn, peas, beans, field corn is so diverse, which gives us extra challenges to think about.

4:22
What can we credit and what we can try to learn more about?

4:26
And another thing is irrigation, right?

4:30
A lot of the wells through university research have we have found that have present high concentration of nitrates in the pivot wells.

4:38
Is it is there a possibility to credit some of it into our field management?

4:44
These are all very interesting questions when it comes to reducing nitrogen loss in this system.

4:50
Yes, definitely.

4:51
So is the university, or your program working with farmers on different projects to so they can understand on how nitrogen moves or any of the other nitrogen nutrients move on their fields.

5:04
Absolutely.

5:06
As everything goes when it comes to measuring water quality, it becomes another challenging thing, right?

5:12
Because we are essentially trying to capture water movement right below where we’re standing.

5:18
And that’s a challenging thing, right?

5:21
Hydrologist and agronomist have been working on this question for decades and decades.

5:27
We’re very lucky here in Wisconsin to have multiple projects on nitrogen leaching monitoring throughout the state happening right now.

5:35
So one of the projects I want to stress on today is nitrogen optimization pilot program.

5:41
Within that program funded by Wisconsin Department of Trade and Consumer Protection, we are able to have multiple nitrogen leaching projects installed within the state to look at how different practices affect nitrogen loss in our fields.

5:59
And this morning we were working on installing some of these resin lysimeter that can potentially help us answer some of our questions on nitrogen leaching and the movement and relationship with the practices.

6:14
So that’s program #1 of course, I have to plug my own program, add water program within extension.

6:22
You can go to our website and with the link attached in the description of this video, we have webinars.

6:28
We have beautiful content, all nitrogen leaching when it comes to the dynamics of how water moves, how different practices can affect nitrogen leaching and of course, dense program nutrient and pest management where they go into more nutrient management planning and other amazing content.

6:48
So check out our extension links and our colleagues are doing amazing work and farmers can get involved by just contacting your local agent.

6:58
I am located in Stevens Point covering central Wisconsin, but we have colleagues all over the state.

7:04
Exactly.

7:04
And you will be able to find one within your area within just a phone call.

7:09
Great, thank you so much today.

7:11
Goulong

7:11
Thank you, Dan.