NIAB - National Institute of Agricultural Botany

Orson's Oracle

Achieving high yields

Posted on 01/10/2014 by Jim Orson

Cambridge recently had an open weekend. Amongst other things, it includedCambridge Backs the colleges opening their doors and also, in some cases, their gardens and libraries. There was an Elizabethan theme as it is 450 years since Good Queen Bess visited the city; hence some colleges had wonderful Tudor manuscripts on display. One of the events was Evensong at Kings College in the presence of Queen Bess (a professional look-alike!) and her entourage in period costume with music and an order of service appropriate to that age. We really enjoyed the day.

Whilst walking round St John’s Chapel my wife noticed a plaque on the wall in memory of Frederick Blackman, the plant physiologist who died in 1947. This brought back memories of university lectures. Blackman was the guy who worked out the details of gas exchange in plants during photosynthesis - during the day it was carbon dioxide in and oxygen out etc.

Blackman may not even have considered that his work would be relevant to the debate about climate change. For instance, a recent German report says that some species of trees are now growing very significantly faster than in the past due to increased carbon dioxide levels in the air.

Around ten or so years ago crop physiologists at Rothamsted Research proved that in growth chambers (where one factor affecting growth can be changed) an increased concentration of carbon dioxide in the air would increase cereal yields. We’ve not seen this clearly demonstrated in real life because of the complexities of growth and of identifying the precise role of individual factors in a particular season.

Blackman recognised this problem and put forward the law of limiting factors in 1905. This proposed that when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. This is why it’s so difficult to predict yields of most crops in the UK. Solar radiation is a major driver of photosynthesis but plants under moisture stress will not photosynthesise at the potential rate set on a very sunny day. Sunny summers tend to be dry summers and dull summers tend to be wet summers.Wheat

We have only to go back to 2007 and 2012 to see that in wet summers there is insufficient sunshine to support even average wheat yields. This year has been sunnier than average, and there have been very good yields where the thunder storms provided sufficient moisture during grain fill.

However, it’s not even as simple as that. Warm nights mean that the rate of respiration is increased taking the edge off the photosynthetic gains during the day. In addition, extremely hot days, particularly during flowering, can reduce pollen viability (hence reducing grain numbers) as well as encourage early leaf senescence and reduce chlorophyll content of leaves leading to a permanent reduction in the yield potential of the crop. Warmer weather than average reduces the time to harvest and hence reduces the number of days when the crop can put on weight.

Perhaps the most recent period of ideal weather for wheat yields occurred during the first week of June last year. At that time the crop was not under moisture stress and it was very sunny but relatively cool during the day and cold at night.

So the rate of yield accumulation, as Blackman hypothesised, may well be limited to the pace of one particular factor but the limiting factor may continually change during the growing season. Trying to sort out the precise role of increased carbon dioxide levels amongst all this is impossible. What we really need is sun but not heat and a good supply but not an oversupply of moisture. No wonder farmers are always complaining about the weather; it is rarely perfect.

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Giant slugs and giant problems

Posted on 23/09/2014 by Jim Orson

I’m sure I heard it first on BBCR4’s Today programme but I can’t find a record of it. Then I met a person outside our house who confirmed it. In fact, he said that his dad had mistaken one for a large stick when taking his dog for a walk late one evening. What am I talking about? Garden slugs: they are ENORMOUS this year.Giant slugs

Over the last couple of weeks I have upped my anti against slugs in the garden. This has meant rather than just relying on metaldehyde pellets, I’ve roamed the lawn in the dark picking slugs and transporting them to a large open area for the birds to eat the next morning. It’s Integrated Pest Management and encouraging bird numbers all rolled into one.

I hope that my metaldehyde use is not contaminating water. The garden is not underdrained and slopes away from any hard surfaces. However, metaldehyde in water has been an issue ever since the river companies developed a method of measuring it with sufficient accuracy to say when levels in water exceed the Drinking Water Directive limit of 0.1 parts per billion (ppb).

The problem with metaldehyde is that the processes installed at waterworks to remove small Directive exceedances of nearly all pesticides don’t do much at all in reducing the levels of metaldehyde. It’s neither strongly adsorbed by the activated carbon beds nor oxidised by the ozone treatment. Hence, unlike most pesticides, the raw water going into the treatment works has to comply with the Directive.

The very active Metaldehyde Stewardship Group has for the past few years been providing guidance in its Pelletwise campaign in order to reduce metaldehyde movement to water. This autumn’s guidance document reflects the increasing pressure on the future use of this pesticide. Quite rightly the guidance has adopted a targeted and conditional approach. There is little doubt in my mind that adopting best practice, particularly in identified high risk fields, will significantly reduce pesticide movement to water.Get Pelletwise

It comes as a surprise to most people that pesticide movement to water through the soil is not influenced by the solubility of the pesticide. Glyphosate is one of the most soluble pesticides available but does not move through the soil to watercourses. Its presence in water is largely determined by spray drift and its wide usage on hard surfaces.

The ability of pesticides to move through the soil to water is mainly determined by how strongly they are adsorbed by the soil (glyphosate is strongly adsorbed by the soil) and their persistence in the soil. There is a relatively simple calculation based on these two measurements which indicates the level of risk of movement through the soil. It’s called the Groundwater Ubiquity Score (GUS). Despite being relatively simple it’s surprisingly accurate, but of course more precise models are used in pesticide registration. It was developed by Gustafson (another reason for the abbreviation GUS), a Monsanto scientist who published the approach in 1989.

The GUS score for metaldehyde suggests that (marginally) it should not move through the soil in sufficient quantities to cause a problem. There are perhaps three possible explanations as to why it is occurring in water.

Firstly, that it is moving to water through different routes. There is little doubt that run-off from fields and the washings from contaminated equipment are a source of metaldehyde in watercourses. However, I understand that movement through soil has been confirmed as a route by the Metaldehyde Stewardship Group.

Secondly, this is an exception that proves the rule for the GUS score. This is a possibility but somehow I doubt it.

Finally, there may be something about the use of metaldehyde that the GUS score does not take into account. This may be the explanation. The GUS score assumes that the pesticide is applied directly to the soil but this is not the case with metaldehyde. It’s necessarily applied in pellet form and so is not immediately adsorbed by the soil. This may influence how long it persists in the soil environment and possibly undermines the methodology used in calculating its GUS score.

I must dash as it is now dark and I must continue with my slug patrol.

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Replacing equipment

Posted on 17/09/2014 by Jim Orson

We have just bought a new toaster. The old one had a broken handle and so it had to go. I could not help but be reminded of the contrast between replacing this slightly faulty toaster with mind-sets when we were first married in the 1970s. Then we would not dream of replacing a piece of household equipment with a slight fault. Indeed I remember going down town in Chelmsford to get a replacement heating element for our ailing toaster. Then there were glorious, but shabby and shambolic, backstreet shops selling spare parts for all kinds of electrical equipment. Sure enough in a back room of one such shop was the replacement element for the toaster, stored in a dusty cardboard box. All I had to do was to take it home and using a soldering iron remove the old element and fit the replacement. I suppose it took up half of a Saturday. Then weekends often also involved servicing our car; a relatively simple and straightforward task.

The same philosophy used to apply to farm equipment. At that time large arable farms, perhaps those above 400 hectares (1,000 acres), generally had a substantial workshop and a full time mechanic. Some of these workshops were shambolic but others as immaculate as they could be in the circumstances. At that time farm machinery was far simpler, yet seemed to require constant attention and maintenance. I remember particularly that there was at least an hour spent greasing a combine every morning during harvest.New farm machinery

Nowadays, our car is so complicated that it is impossible for me to service it. Likewise, farm machinery is also much more reliable, but complicated enough that it has to be maintained by off-farm specialist mechanics.

In general arable farms are now equipped with a narrow range of relatively new machines. However, what are the short term prospects for the machinery trade with the market price of combinable crops now being below the cost of production? It seems likely to me that most specialist arable farmers could continue a year or two at least without replacing any machinery - but will they?

During the bad times at the turn of the millennium, the machinery trade was partially sustained by the necessary increase in the productivity of arable farming, including the changes in primary cultivations that were taking place. In particular, sales of large tractors and primary non-inversion cultivators seemed to be the order of the day. This may not be true this time around but the move by some farmers towards controlled traffic farming is stimulating some machinery replacements. Now, at last, not only is the width of cultivators more likely to fit in with this practice but also combines as well. The latter have in the past been commonly difficult or impossible to fit into a controlled traffic system.

I’ve been asking farmers about their views on machinery replacements in the context of the current commodity prices. A minority have said that they will continue to renew and upgrade machines regardless of the current financial situation. However, they add that if things get particularly nasty they could probably continue their businesses for five years or so without any machinery purchases.

The majority have told me that the current farmgate prices will result in some reduction of machinery purchases. A couple of farmers have said that they will stop replacing non-essential machines. I have a problem with this; should there be non-essential machines on farms or have I slightly misinterpreted the description of ‘non-essential’?

There generally appears to be the intention to keep core equipment up to date but the timings for replacements may slip a year or two. This is particularly true for new combines where I’m told that the relative prices of one and two year-old machines have declined and so the replacement costs have increased.  

One or two farmers have told me that black-grass (well I had to mention it at some stage!) may result in changes in their machinery strategy. The introduction of significant areas of spring cropping has changed the machinery and labour profiles on their farms and they are considering what this may mean for machinery complements in the future.

However, one thing is for sure. No arable farmers are contemplating employing full-time mechanics when eating their toast in the morning!

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Food sales fall for the first time

Posted on 08/09/2014 by Jim Orson

Last week the papers reported that for the first time since the monthly statistics were gathered (January 1989), the quantity of food sold in a particular month in GB fell when compared to the same month in the previous year. In July 2014 the quantity of food sold fell by 1.5% when compared to July 2013, sales were 1.3% down and food prices inflated by 0.2%. It’s interesting that food was the only section of retail to have higher prices in July 2014 compared to July 2013 (see Table).

There were more than a few column inches written about austerity and the lack of real wage increases being the cause of this first recorded fall in the volume of food bought. This may partially be the cause but there may also be other more positive explanations.

Some of the fall might be explained by a reduction in food waste and hopefully, this will have an impact on food sales in the future. Much has been made of the ‘best before’ dates increasing food waste and I am sure that they are understandably super-precautionary. My own experience suggests that yoghurts can be eaten a week after the ‘best- before’ dates with no ill effects! Another possible contribution to the fall in food volumes sold might be that we are eating less and hopefully better quality food because of the increasing concerns over obesity.

These newspaper articles encouraged me to look at the monthly reports on retail sales produced by the Office for National Statistics. Each report is huge with page after page of statistics and it is easy to be put off trying to read and understand it. However, there are very well written summaries for each retail sector and things become clearer after a while.

I picked up some interesting facts (well, they’re interesting to me!). In July 2014, for every pound spent in the whole of the retail industry (including online), £0.42 was spent in food stores, £0.41 in non-food stores, £0.06 pence in non-store retailing (e.g. mail order, catalogues and market stalls) and £0.11 in stores selling automotive fuel (i.e. petrol stations). This demonstrates that food still is the largest retail sector, but not by much. The only other of these main retail sectors to experience a fall in volumes over the year was ‘automotive fuel’ which fell by 4.7% (see Table). In fact the quantity of fuel sales seems to fall regularly, perhaps explaining the rapid loss of rural petrol stations.

Retail sales for GB, July 2014

Overall, online sales grew by over 11% over the last year. Only 3.7% of food sales were online in July 2014 compared to exactly two thirds of non-store retailing.

Food retailing seems to be in transition despite the relatively low proportion of online sales. The business sections of newspapers have all been giving the big food retailers advice on how to handle the fact that consumers are getting savvier and can now seem better able to work out if they are getting good value for their money. This means that consumers are becoming less loyal to one supermarket chain and as a consequence, they are less likely to do a ‘big shop’ at their previously favoured superstore. The supermarkets that are suffering are those that bridge the gap between the discounters (Aldi and Lidl) and the high end of the market (Waitrose and Marks & Spencer) [As an aside, I remember Alan Coren saying that Sainsbury’s existed to keep the riff-raff out of Waitrose]. A fall in the total volume of food sales is probably the last thing any food retailer needs, particularly those that are already suffering from decreased sales.

The general advice offered by the newspapers (as if they know best!) is that those supermarket companies that are stuck in the middle will have to become more price competitive and offer greater value. The papers also say that they will achieve this with lower margins and less spend on store refurbishment. Well, I hope that this is the case rather than further squeezing their suppliers. In many cases market prices for farmers are already below the cost of production and the room for a further squeeze on farm prices is just not there.

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If all else fails – do a trial

Posted on 28/08/2014 by Jim Orson

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?

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