Monday, July 29, 2013

Reduce Nitrate Leaching With The Mobile Milking System

Unconventional ways to reduce nitrate leaching

Part 1 
A few weeks ago I explained how agroforestry is a farming system that is able to reduce nitrate leaching.

Part 2
Today I will talk about how a dairy farming system based around a mobile cowshed is able to reduce the level of nitrate leaching.

A traditional cowshed is in a fixed location. The cows have to be within walking distance of the cowshed because they need to get milked twice a day.

The main cause of nitrate leaching on dairy farms in the cows urine patch.

For this reason, the cows are always grazed on the same block of land surrounding the cowshed.

What this means is the cows are rotating around the same block of land every 15-30 days, urinating  on the same paddocks month after month, year after year. 

By making the cowshed mobile, we also make the herd mobile and that allows the cows to move to other blocks of land throughout the year.

Essentially spreading the urine/nitrogen over a larger area and therefore reducing the concentration of urine on each single block of land.

It's a totally different farming system, but could be one method farmers use to reduce their nitrate leaching levels.


  1. Given you have repeatedly presented Urine as the problem - is shifting the urine to different farmers improving things? Same number of cows, same amount of urine.

    Dr Keith Cameron has told me urine patches make up about 20% of the area.

    1. I suppose urine patches would make up about 20% of the area. But it's the fact that there is so much nitrogen in that urine patch.

      This is from DR Doug Edmeades web site.

      "The major source of nitrate leaching is from urine patches. When animals urinate they apply between 300 to 600 kg N/ha in small patches. Managing nitrate leaching is about managing the number of urinations per unit area when the soil is already wet (i.e. in the autumn-winter periods)."

      What I'm advocating in this post is that, by moving the herd of cows to other areas of land, we are reducing the number of urinations on one particular piece of land.

      Here are another good video outlining water quality issues, including N leaching by Dr Jan Wright. In her presentation she states that 85% of N leaching on a dairy farm is due to cow urine.

  2. You didn't grasp my question. How does shifting cows to different farms reduce nitrate getting into our water. You are not reducing urine are you?

    1. No we are not reducing the amount of urine, we are just distributing it over a larger area. Therefore there are less urination's per ha.

  3. Am I correct in saying that you are essentially suggesting to reduce stocking rate as you are grazing the same number of cows over a greater area? Reducing stocking rate will definitely reduce nitrate leaching. Probably less profitable but as stricter regulations become more likely it may become a necessity! We can also reduce nitrate leaching by reducing urinary N concentrations through dietary manipulation which may prove more practical and more profitable!


    1. Yes and no.

      If we use a cropping farm as an example. Usually a cropping farmer will have a crop rotation. A typical Canterbury cropping farmer may plant a Ryegrass crop which they harvest for seed, then they follow that crop with a wheat crop and then follow the wheat crop into some other crop.

      What I am advocating with the mobile cowshed is a dairy farmer could move his cows onto that ryegrass crop after it has been harvested for seed.

      Currently the cropping farmer may graze cattle or calves on that ryegrass land for $10-$20/head/week. But now it is an option for him to have a dairy farmer milk cows off it. It may only be for 3 months of the year.

      From a nitrate/urine point of view, for 3 months of the year the cows have moved onto a different block of land.

      The next year the cropping farmer would be planting a different block of land into ryegrass. If we assume that the dairy cows return the following year for 3 months then they are on a totally different block of land that has not had cows on it before or for a long time.

      It's not really reducing the stocking rate at all. You can still have the cows at 3-4 cows/ha but the cows are grazed on different blocks of land year after year.

      It's really just integrating dairy cows onto other farming systems for parts of the year.
      The mobile cowshed makes this possible.

      I'm not sure if I explained my self very well.


  4. Gidday Glen,
    Still don't understand at all.
    Are you suggesting that urine patches are less of an issue if are further away from each other even if there are the same number of Urine patches? If so why? Do urine patches affect each other?

    In a previous post you have the average N leaching from dairy at 65kg/ha and mixed cropping at 61kg/ha. By adding urine to mixed cropping are you helping? Keeping in mind your Dairy issue has 'hotspots' where mixed cropping has 'even but high'. If you add hotspots to 'even but high' aren't you making the problem worse. Ryegrass seed gets LOTS of nitrogen.

    Mr E

    1. Hi
      No thats not what I'm meaning.

      I might do a more detailed post. I know what you're saying about the cropping N leaching, but if a dairy system were integrated into a cropping system, you could farm differently.

      I'll clarify shortly.