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Saturday, May 25, 2013

Cow urine

Glen Herud @ Milking on the Moove talks about cow urine.

Urine Patch Contains Equivalent to 800kg Nitrogen per Ha
Here's what happens. Basically, here is a cow. This is a bit of a funny cow. She's a Friesian so what she does is she urinates into what you call a urine patch, which is about the size of a dinner plate. Within that dinner plate, there are 800 KGs of nitrogen per hectare. So there is an equivalent to 80 KGs of nitrogen per hectare. So the way I think of that, to make sense of it is if you take a hectare, which is a football field and let's say we had a way of getting all these cows lined up so they all urinated at once and all the urine patches covered one whole hectare. If they all urinated at once, that would be applying 800 KGs of nitrogen per hectare at once.

Average NZ Dairy Farmer Applies 150-200kg Nitrogen per Ha per Year
To give you an indication of how much that is, your average dairy farmer does around 150 to 200 KGs of nitrogen per hectare per year. They will do that over multiple small allocations of fertilizer. So, what I want to sort of get through to you is that there is a heck of a lot of nitrogen in a urine patch. What happens is that if you think about grass. I don't know, what we got? Five, six, seven grass plants within a urine patch? They've got their roots systems that go like that, probably around 30 centimeters deep. So what happens is the nitrogen comes in via the urine and while it's in the soil it turns into nitrate. It can be absorbed by the plants. If you look at this picture here, you can see these dark green patches in the paddock there. Those are fertility patches. They are either feces patches or urine patches. What's happened is that those grass plants there, have as much nitrogen as they can get and they've bolted away and they are nice and dark and green.

The Few Grass Plants in a Urine Patch can't Absorb all the 800kg of N
The problem is that there are 800 KGs of nitrogen being applied. Well, a heck of a lot of nitrogen will be applied and those few little plants, there is absolutely no way they are going to be able to absorb all that nitrogen. There is far too much.

What happens is the nitrate attaches to water molecules, H2O, because nitrate is soluble in water. Those water molecules filter down through the soil profile and drain away and they take the nitrate with them. Once they get below the roots’ depth of the plants, they can't get absorbed. It keeps on going, all the way down, until it gets into our groundwater. Then it ends up in our waterways. So that is very simply how nitrate leaching takes place. Essentially, excess nitrate that isn't absorbed by the plants ends up filtering through the soil profile and getting into our groundwater.

There are a couple of things that affect the rate of nitrate leaching. One of them is your soil profile. If you've got nice, well I shouldn't say nice, if you've got free draining soils that are kind of rocky, the water flows through those soils much more quickly. So, obviously the nitrate flows through quicker. If you've got heavier clay soils, then the water sort of sits there more and therefore the nitrates sits there more. The amount of water in the soil profile affects the rate of nitrate leaching. What happens generally is during the summer lots of nitrogen is sort of applied and it sort of sits there in the soil and then winter comes along and we get all this wet weather and it all sort of leaches out through the winter. What's the other thing that affects nitrate leaching? Oh, your plants, your root depths. If we can get plants that have twice the root depths, then there are obviously twice as much time for them to absorb nitrate. That's a very brief rundown. It will probably horrify a few scientists but that sort of serves the purpose of what we need to explain today.

So the next little while I'll start talking about how we can farm differently in ways to reduce our nitrogen leaching cap or nitrogen leaching rate. If you have been following the news you'll see that regional councils are starting to sort of propose nitrate caps, so saying that you can only leach around 25 KGs of nitrogen per hectare per year. Obviously, if you are a potato grower, they would horrify you and dairy farmers are equally worried about how they are going to be able to farm and meet that sort of a target. That's what I want to talk about in the next couple of weeks.


paulinem said...

Robert ..if I wanted to hear the discussion etc in the AP at ES meeting...whats the best time to come and watch..I see its on Wednesday and Thursday morning .... I was hoping to come Wednesday morning (as not availble thursday) would there be much discussion then on the water and dairy farming ..also can you tell me a dairy farmer rang me and suggested the water ways have much cleaner lately as most cow cockies have cleaned up there act and are doing all they can to prevent pollution etc ..he suggested if they didnt Fonterra refused to take their milk this true !! I haven't been out much in the country area lately so I am not so informed if its true!

robertguyton said...

Wednesday, starting at 9:00 am, Pauline. I'll be there, give me a wave when you come in:-)
I don't know what order they'll be heard in, so can't advise you yet. If the room is full of dairy farmers when you get there, you can bet we won't have to wait long til we are discussing the rates.
Dairy farmers 'doing all they ca' to prevent pollution? I don't think that's true. they are doing more than they used to, most of them, but there are ideas I could suggest, to achieve even more.
Fonterra says it's refusing to take milk, but you should see if you can track down one farmers who has experienced this. You'll be digging very deep. That said, Fonterra should be at the hard end of threats over bad practice, and following them up too.

paulinem said...

Thanks . could be more like 10am ..that gives time for the boring prelims etc :) ..will have to leave about 12am working at St Vinnies in the afternoon.... dairy..yeah ..I do get the small just got into the business farmer would get penalised with these rate cahnges and I do beleive id a cocky can show they are relally trying hard not to pollute etc they should be rewarded

As I see one cap doesn't fit all re dairy farmers... my personal knife has always been with the corporate owners whom focus has always by the nature of the investment been on profit .... that letter I sent in and could get published tomorrow about govt getting tough with hard laws came from my environment studies ..apparently quite a few countries have hard environment laws ..sadly all we have is a lot of vocal puffery from our govt in getting tough with those that deliberately pollute the environment ie totally focused on the profit margin and over stock over pollute ... Can you imagine if we treated our traffic problems with a load of puffery and didnt have hard laws to deter traffic defaulters like speedsters ( on th news today that the police picked up two cars of youths travelling at 180 km per hour and 170 km per hour ..they confiscated the cars) speedsters are polluting the road ways ..dairy cockies that do nothing about polluting and overstock the land are just as bad as traffic polluters ...mind you been a townie I would love if we had hard pollution of environment laws to see a get tough with those that throw bottles of alco pop onto the foot paths be given a stiff punishment as well !! Ahh well that's my rant for the day time to get tea ready all going well should see you on Wednesday morning :)

robertguyton said...

Confiscate the cows!
Now you're talking turkey, Pauline.
Shout it out on Wednesday, if the dairymen start to boo (wouldn't be the first time :-)