0800 843 809 info@esi.org.nz

Peter Burton

13th May 2019

Because it is under permanent grazed pasture that carbon can be most readily sequestered pastoral farmers should be excited about an economy that is putting increased focus and value on carbon.

And yet we’re not, for the very good reason that intensive pastoral farming as practised on most dairy properties results in a loss of carbon.

One of our leading research scientists in a discussion a little over two years ago stated that all irrigated land in this country “without exception” was losing carbon.

The question is, how is it that adding water resulting in increased pasture production causes carbon to be lost?

More pasture growth results in more carbon dioxide being sucked in by plants, oxygen is then released with the carbon fraction being stored in the soil.  Yet that process doesn’t appear to be working.

Maybe the measures aren’t accurate, or the wrong stuff is being measured.  That would seem unlikely.  More likely is that something is happening in the soil that is stopping the natural process of carbon sequestration occurring.

It’s an important issue because where extra carbon is stored, more nitrogen can be captured and held resulting in less being lost via leaching to groundwater.

For this reason, intensive pastoral farming should be encouraged, particularly in sensitive catchment areas.  Yet the reverse is the case with the consequence that livestock farming will become less intensive with catchment areas being increasingly planted in trees.

There are intensive, highly productive pastoral properties that are carbon positive, but they are in the minority.

The reason some do but most don’t comes down to the frequency and amount of nitrogen fertiliser applied, and a three year study by a recognised research institute could confirm that and also identify the reasons for it occurring.

Dr Christine Jones states that for carbon to be sequestered in the soil, particularly in a form that is resistant to loss, specific microbial activity is necessary.

The frequent application of fertiliser nitrogen creates an environment whereby soil microbes are unable to carry out this function and carbon as a result is steadily lost.

With less carbon in the soil, moisture and nutrient holding capacity is reduced and annual pasture production declines.  That’s been the case here for the last forty years and as time goes on it is becoming increasingly apparent.

To counter that loss, farms have become increasingly reliant on cheap brought in feed, and more grazing off.  The days of cheap PKE are numbered and unless a fair price is paid for hay, silage, and balage it will become increasingly scarce and more expensive.

Quality grazing will also in time reflect the true cost of growing that feed and prices will inevitably lift.

Perhaps the greatest concern at present is the price of land. Fewer farms are selling and they are taking longer to sell.  The solution is a reduction in prices being asked.  If the price of farms halved more would sell, however the consequences of that would result in huge upheaval.

The obvious solution to all the above issues is to move from a fertiliser nitrogen reliant system to one where the same amount of N is available as a result of natural soil processes.

And for those who think this change isn’t feasible or plausible even folk at the major fertiliser companies acknowledge that change is imminent and probably a good thing.

Many rightly argue that any change must be science driven. Making the science available is just a matter of demanding that the research be undertaken.  The long-term consequence of not doing so is a significant reduction in our pastoral farming industry and resultant land prices that are anyone’s guess. For more information call Peter on 0800 843 809.

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