Over recent times there has been much debate around the topic of ‘biological farming’.  As little if any nutrient enters a plant without first going through a biological process, all growing systems regardless of the label applied to them are essentially biological systems.

The most important issue presently, and is the one at the heart of the debate around different growing systems, is the use of fertiliser nitrogen.

Excess fertiliser nitrogen reduces the humus content of soil and when used regularly to promote growth, total pasture production steadily declines.  Recent work from AgResearch shows an 18% decline in pasture growth in the second season after establishment of new pasture.

What we often observe is that where there is a dependence on nitrogen fertiliser, by the end of the fifth year the gaps between grass plants have steadily increased,  a significant number of plants have been lost due to pulling in autumn, excess rain ponds for longer periods and total growth reaches a level where regrassing becomes the only option.

What is now well understood is that at least half of applied fertiliser nitrogen does not enter the targeted plant.  Some is lost direct to the atmosphere with the remainder finding its way into groundwater, and Ministry of the Environment figures show a steady increase in Nitrate-N levels in areas where intensive dairy farming is carried out.

Fertiliser nitrogen can be a useful tool; it’s the dependence on it that needs to be sorted.  We only have to look to growing systems in Europe to know that its future use will be increasingly regulated.  Farmers have the choice to modify their systems now, or wait until regulation arrives and other people start making decisions for them

To know whether a property has a dependence on fertiliser nitrogen simply stop applying it, all of it.  If the result is less growth then there’s a dependency issue, it’s a simple test for any addiction, and the addiction to fertiliser nitrogen is evidenced by urea silos on farms.

But it doesn’t have to be.  The use of DoloZest and CalciZest, soil improvers sold under the Functional Fertiliser brand are being increasingly used to successfully replace fertiliser nitrogen.

The measures collected over a number of years from the Berryman property, an intensive dairy operation near Edgecumbe, using a DoloZest/CalciZest based total nutrient programme, show total pasture growth based on Overseer to have been in excess of 19 tonne for each of the 2010-11 and 2011 -12 seasons.

Pasture cages showed growth for those seasons to be 18.4 and 18.3 tonne respectively, with less than 20kgN/ha applied each year.  Total milksolid production was in excess of 1,300kg/ha from an average of 200 cows, with around 20% of the total feed being bought in.

Long strong stemmed clovers flourish throughout the major growing season providing exceptional growth of calves and contribute significantly to the 0.87:1 protein to fat ratio of the milk produced.

Clover flea and weevil under close examination can still be found however given the health of the clover damage is minimal.  Careful digging and sifting also turns up the occasional grass grub and beetle larvae but again too few to cause damage.

Total nitrogen tests showed 9,400kgN/ha in the top 30cm of the soil with 200kg N/ha available for plant use at the time of testing.

With increased carbon sequestered each year and more humus formed, a steady increase in pasture growth and total farm production can be expected, and with measuring continuing more data will be made available.    For further information, please call Peter on 0800 843 809.

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