# Nitrates in Weeds, Again



## Texasmark (Dec 20, 2011)

Was reading some time ago about weeds picking up nitrates and all during stress and in heavy traffic areas. I use moderate amounts of an Ammonium Sulfate, or Urea/Amm/Sul. fertilizer, for one reason to reduce my nitrates.

I started calving season about a week ago and moved my cows into a pasture that I had mowed a few days prior having bermuda, some native grasses, and weeds; same makeup as where they were. I did notice that the weeds were a deep green color, much greener than my grasses, as they were in the other pasture.

As soon as they hit my bull started eating a weed that had a central root like clovers but spreads across the ground with shoots and fishbone like oval leaves. I had a bale of hay there and they ignored it for the first couple of days.

Within a couple of days, the bull had a pretty good scoured rear which cleared up in a couple more days as the weeds dwindled.

Soooo, if that's not what people talk about in nitrates in weeds I don't know what else it would be.
--------------------------
On the bull with the cows, I bought them spring '11 as yearlings and they have been together the whole time. I thought about separating him out but didn't because he would have been alone with fence access to the cows and we have a tremendous buzzard problem here and they just love downed cows and baby calves. Having him with them would just help in chasing the buzzards off.

As it turned out, the first one calved and the others left her and the baby alone. Things have worked out great.

My 2c,
Mark


----------



## hayray (Feb 23, 2009)

I believe that would be nitrogen in the form of excess protien but I don't think that is the same as nitrates turning into the extreamly toxic nitrite poison?


----------



## Texasmark (Dec 20, 2011)

hayray said:


> I believe that would be nitrogen in the form of excess protien but I don't think that is the same as nitrates turning into the extreamly toxic nitrite poison?


That has been a question of mine and that is what nitrate from where. I always thought that NP comes from using Ammonium Nitrate fertilizer winding up with accumulations in plants. Then I picked up on some suggestions that it comes from the soil....but how does it get there?

I really like the fact that these animals are weed acclimated to weeds. In the late summer around here we have a crop that is seasonal and prolific. Central root like clover, grows close to the ground and has little white flowers with yellow centers....some purple on there somewhere also. They just love them.

Thanks for the reply,
Mark


----------



## vhaby (Dec 30, 2009)

Except in moderately to strongly acid soils, fertilizer N applied as ammonium is converted to nitrate. Acid loving plants such as rhododendron (azalea and blueberry) prefer uptake of the ammonium form of N. Most other plants prefer well limed to basic (alkaline) soils where the nitrate form of N predominates. Why?

In the well limed to alkaline soils, bacteria (nitrosomonas and nitrobacter) are most active. The nitrosimonas bacteria convert the ammonium forms of N to nitrites and then nitrobacter rapidly convert the nitrites to nitrates.

So, eventhough you apply urea, ammonium sulfate, or urea ammonium sulfate to your alkaline soils, the ammonium is converted to nitrate and taken up as nitrate by the plants. Certainly not all ammonium is converted to nitrate, so the plant still obtains some of its N as ammonium. The scouring you referred to is due to high levels of N as crude protein in the forage, not nitrates. If you seed ryegrass for winter pasture, you will note a similar response from your cattle when they are grazing this high crude protein ryegrass.

This said, you don't need to fear using the ammonium nitrate form of N fertilizer. Currently, ammonium nitrate is quite a bit cheaper per pound of actual N than is ammonium sulfate, but as you know, plants also get sulfur from ammonium sulfate.


----------

