If all else fails – do a trial

28 Aug 2014

Is Woody Allen a genius who saw through the food police’s plot to stop us enjoying life? His 1973 film ‘Sleeper’ was about civilization 300 years hence and it derived great amusement from the 1970s trendy issue of not eating saturated fats. It seems he may well have been correct. An Israeli scientist has carried out a well designed and run trial which has shown that those on a diet that did not constrict the use of foods containing saturated fats lost more weight and ended up healthier than those on a Mediterranean diet or those on a low fat diet. Now the medics are lining up to explain why this result is plausible.Milk

Possibly this means that the decades I have spent consuming semi-skimmed milk and using vegetable oil-based  spreads rather than butter may have had the double whammy not only of me enjoying less the food I ate but also of it potentially doing me harm. My wife is also impressed with the evidence from the trial and there is now blue-topped milk in the fridge along with a more packs of butter. Life is already better.

Sugar is the real ‘enemy’ in diets. It is clear that in many cases the ‘low-fat’ alternatives are stuffed full with sugar in order to replace the role of fats in making a tasty and stable product.  

If these results are to be believed it shows that we have all been misled by theories based on limited or incomplete knowledge because nobody carried out trials. In all realms of life we might benefit from doing more trials. Development economists and social scientists are increasingly doing more trials which often provide answers that, at first, sound counter-intuitive. However, real progress has been made when the results of these trials are analysed and are used to form the foundation for new strategies.

Luckily, arable agriculture has a long history of field trials. Hopefully, these are well designed and executed and the results analysed and interpreted for the benefit of the industry. I suppose this usually occurs but there are exceptions, usually at the analysis and interpretation stage.

There was the classic misinterpretation of the recent HGCA-funded trials on the use of micronutrients in wheat production. I hasten to say this misinterpretation was not done by HGCA or the scientists doing the trial. I’m not sure whose fault it was but it is clear that farmers are being told that on average there was an economic response.

In fact this was disingenuous. In the fifteen trials that were carried out, each measuring the impact of three different micronutrients, there were only two responses out of 45 comparisons and these would have been expected from soil analyses. In the remaining situations there were no responses but there was inevitably the variation that occurs in biological systems. This variation meant that there were small numerical but not statistically significant decreases in yields from the use of micronutrients in some trials and these were almost exactly matched by small numerical increases in other trials.

The disingenuous interpretation was that on average the ‘responses’ would have paid for the input. I talked more fully about the results in my blog ‘Micronutrients fail the ‘common sense’ test’ published in October last year.

Then there is the situation where the results of trials are clear but they are ignored because they do not confirm current theories. This is reminiscent of attitudes in the Dark Ages. I know that  I’ve said this many times before but it is absolutely clear from all the data that have been generated over the past 20 years that the efficiency of use of soil mineral nitrogen by wheat is not the 100% that is assumed in ‘official ‘ recommendation systems. The figure is more like 50%.

The assumption of 100% efficiency means that, currently in ‘RB209 – The Fertiliser Manual’, for every increase in N index from 1 to 3 the amount of applied N recommended falls by 30 kg/ha. I have been told that one reason for not adopting a system that more closely reflects reality is that it is too complicated. Well I hate to disagree because all that is required is to reduce the recommendation by 15 kg/ha rather than 30 kg/ha. It is certainly not rocket science.

Going back to diets, I just wonder if the new information challenging the low fat culture will reflect on the popularity of a coffee option in Australia. There is the ‘why bother latte’ which consists of organic decaffeinated coffee, fully-skimmed milk and no sugar. Are its days numbered?