0800 843 809 info@esi.org.nz

By P.W. Burton

Science, according to the Concise Oxford Dictionary, is systematic and formulated knowledge.  Primarily it’s about measures, and when it comes to fertiliser it’s about performance measured over time.

Soil fertility programmes here were developed initially from measures taken in the 1940’s and 50’s by DSIR (Dept Scientific and Industrial Research), later to become MAF (Ministry of Agriculture and Fisheries).

A cornerstone of the work carried out by the various Research Institutes throughout the country prior to 1990, was providing farmers with the best and most up-to-date information.  There was no commercial influence then, and trial work required the co-operation of several disciplines for a minimum of ten 10 years.

We regularly now hear of an imminent science breakthrough that will reduce nitrate-N losses and greenhouse gas emissions, as well as remove excess carbon dioxide from the atmosphere.

Even if such a breakthrough was discovered right now, it would be several years before sufficient measures could be made in enough practical farm situations to know that it provided a viable alternative to current practice.

There are no miracle cures about to be released, which means that we either continue with current practices and suffer the environmental and financial consequences, or far reaching regulation is introduced, slashing animal numbers and depriving farmers of their livelihoods.

One possible miracle would be if the long-term data from alternative soil fertility programmes were examined to see whether there’s anything of value.  It would take maybe 90 days for a team of researchers to carefully analyse the data, and take enough measures from the properties of long-term users, to know what of value there is to be learned.

There is plenty that can be learned from the work of those outside mainstream, although it will come too late for at least one of the first people to appreciate that a calcium, rather than phosphorus driven soil fertility system, provided superior results in all respects.

Vaughan Jones, who died recently, was a vociferous advocate of higher than usual inputs of lime and soft phosphate rock along with elemental sulphur as the basis for clover dominant permanent grazed pasture, and time will show he was ahead of his time.

The advantage of the system Vaughan pioneered was steadily increasing pasture growth over time, in contrast to the results from the urea driven system embraced by many today.

There are plenty of measures to show that annual pasture growth has steadily declined with increasing nitrogen use over the last 27 years.  It will be looked back on as a failed strategy, with the damage caused taking decades to recover.

Nitrogen is an essential growth requirement, as important in calcium driven systems as in systems reliant on regular N applications.  The difference is that sufficient N can be made available naturally for pasture growth in excess of 18 tonne of dry matter per hectare per year.

And the claim that nitrogen, whether applied in the form of bag N or fixed by clover, is the same doesn’t stand close scrutiny, due to the short length of time (1994-’96) over which the study was conducted.

Most pastoral soils on which dairy cows currently graze naturally contain 5,000 – 15,000kg N/ha.  Only a small percentage is required for plant growth throughout the season with the majority recycled via dung and urine.

As with all nutrients only 1 – 5% of the total amount is available at any given time for plant uptake.   The key to the success of the clover-based system is that it is fixed in response to declining plant available levels, a far more efficient way of supplying N to plants.

When ideal grazing intervals are adopted plants contain more protein and less nitrate, further reducing the amount of N lost to groundwater.  The measures are available, and those wanting to scrutinise dispassionately may have access to them.

Total N leached may still be above the strictest standards demanded.  However, compared to losses from fertiliser N dependent systems, the reduction is significant.  Not perfection perhaps, but possibly a start point for scientists aware that there is no single magic button in a multi factored natural system.

Our experience is that scientists seldom stray far from their centres of work, even when invited.  Those of us in the field can assist by providing the essential field observations required, if rapid progress that allows farmers to remain viable now and into the future, and the fresh water standards are to be met.

For more information contact Peter on 0800 843 809.

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