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Fertiliser - a big spend on the farm

fertiliser basicsOn sheep and beef farms, when times are good, more money is spent on fertiliser than on any other farm input. But in recent years, many hill country farms have never seen fertiliser an any quantity for over 10 years.

On dairy farms fertiliser was always the biggest spend, but over recent seasons, purchased feed has surpassed fertiliser costs.

But far too often, major amounts of fertiliser investment never produces a true profit, and in many cases it is totally wasted; it's literally money down the drain!

Big confusion on the farm

  • The major problem is 'farmer confusion' over the whole subject of fertilisers, and the role they play in soil fertility and farm profit.
  • Often, the best efforts of people in the fertiliser business doesn't seem to help, and only adds to client misunderstanding of soil and fertiliser issues.
  • So this combination of ignorance and confusion encourages farmers to either put on too little fertiliser, to repeat the dressing their fathers traditionally used, or they get carried away when times improve, assuming 'more is better', without knowing what is really needed.
  • At least they felt happy, even if their soil and farm profit was not improved as a result.

Why the confusion?

There are plenty reasons to chose from.  Here are a few personal thoughts:

  1. Fertilisers involve chemistry and inevitably scientific jargon, which is rarely well explained by boffins.  I can only remember a handful of my old colleagues who could get the subject over to farmers so nobody fell asleep.
  2. Many so-called 'experts' made things worse by their writings, which cover the whole spectrum from fact to fiction. This seems to be no better now than in the past, when MAF was an independent source of soil and fertiliser information.
  3. Fertiliser knowledge demands understanding the complexities of the soil.
  4. New Zealand soils are geologically new and vary greatly, which doesn't help.
  5. Today's 'hot issue' is the implications that fertilisers have on our 'clean & green' environment, and there's science, emotion and politics involved here. Science is the one that's struggling for air!
  6. There is a mind-boggling range of fertilisers on the market - and a similar range of people wanting to sell them, because there's big money involved.
  7. It's not easy for farmers to check the credibility of sales people and consultants, as although the law controls nutrient content of products on the market, anyone can sell 'fertilisers'.
  8. So there's always the 'suspicion' that the people who sell fertilisers, and who also provide fertiliser advice, may recommend more product than is actually needed.
  9. The answer is to check the technical credibility of the people you are dealing with - and don't base this on a fancy business card or brochure.
  10. Over the years, 'experts' have continually disagreed with each other, and have argued their differences in the farming media and at conferences - which has only added to farmer confusion.
  11. I well remember many attempts to get the different sides together to 'sort things out' - but it was a waste of time.  This is still the state of play, and if anything is worse, because of commercial sensitivities. Criticism could end up getting you sued!
  12. To add to the confusion, in recent years, a widening gap has opened between what can be described as 'chemical' fertiliser users, versus the practices covered by the terms 'Biological farming, Organic farming' and Biodynamics'.
  13. Again, the farming media have fed this division, building on the growing assumption that the word 'chemical' is bad, and the word 'organic' is good.  And now it seems this new word 'biological' is the rising star.
  14. This is based on the old rule - 'never let the facts get in the way of a good story'.
  15. The difference between different types of fertilisers (with fancy names) has got very messy, and people from each side are continually doing battle in the media and at field days.  This fuels confusion as people feel they have to take sides.  If you are not for something- then you must be against it.
  16. Consumers' concerns (real and imagined) over 'healthy food' have driven a widening gap (and a fair bit of panic) over what they see as the increasing use of 'chemical' fertilisers - which they assume are bad.
  17. We have short memories and don't record things well enough.
  18. Because of the time lag between applying a fertiliser and seeing the results, it's difficult to work out if you got value for money or not.
  19. Many small farmers who have been persuaded to try some new product, see an initial green flush of growth in the first few months, and assume this 'benefit' will keep on for years.
  20. Major applications of fertiliser to build up basic fertility will not show this flush, so there is no initial flush to impress the neighbours!
  21. Very few farmers do a trial on their farms to test whether they got value for money from a fertiliser.  In any case it's far too difficult. A visual observation is about as much as can be achieved, and this can be very misleading.

Brief fertiliser history

  • Since the dawn of agriculture, applying 'animal manure' was the only way to maintain soil fertility, either directly from manure accumulated when stock were kept indoors over winter, or through 'the golden hoof' where stock ate off crops and treaded their manure into the soil.
  • Animal manure was also called 'Farm Yard Manure' or FYM.
  • It was only in the late 1800s that chemists started to apply their science to the soil, and develop chemicals as fertilisers to boost fertility.
  • So the terms 'natural fertiliser' for animal manure, and 'artificial fertilisers' for those made from chemicals became established.
  • Then to add to the confusion, the terms 'manure' or 'artificial manure' were applied to chemical fertilisers.
  • A text book printed c1900 on 'Live Stock Health & Disease' edited by J. Prince-Sheldon on British farming, states that: 'when used to supplement the manure produced on a farm, artificial manures are of great benefit; but it is open to doubt if they can be successfully made to take the place of farm yard manure wholly through a long series of years.'
  • This shows the dangers of predictions, as in only a few decades the author's predictions proved to be ridiculous, mostly driven by wars, the threat of wars, and the need for more food for increasing populations worldwide.
  • Famous UK research stations such as Rothamstead and Cockle Park in the 1890s started to drive this rapid progress using industrial wastes like slag from iron smelting, old bones and guano rock from accumulated bird droppings.
  • The next stage came when different fertilisers were mixed to form 'compound fertilisers' and their physical form improved into pellets for easier spreading both from the ground and from the air.  This allowed fertilisers to be tailor-made for the particular crops.  This is the situation today.


Special thanks to my former MAF colleague, Dr AHC Roberts, now Chief Scientific Officer at Ravensdown for helpful comment and permission to use his AgResearch information, and to my former fellow student and UK soil consultant, Dr Tom Batey from Aberdeen.

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