NIAB - National Institute of Agricultural Botany

Orson's Oracle

Spray drift without wind assistance

Posted on 03/04/2014 by Jim Orson

We have just spent the weekend in Dorset and yesterday morning our car, like many others, was covered in Saharan dust. It’s no surprise that disease spores can travel hundreds or even thousands of miles if larger dust particles can move with such ease.

Whilst driving back last night, I noticed smoke initially rising from a bonfire and then, rather than spreading out, it travelled ribbon-like horizontally a few metres above the ground before eventually falling back to the ground some distance away. This is typical of temperature inversion that can occur on still evenings after a warm spring day. Such conditions can strongly suppress the dispersion of not only smoke but also other particles such as pesticides.

The condition is called inversion because the air gets warmer rather than cooler with height (i.e. it is the inverse of what typically occurs). In the UK, it is more likely to take place in the spring during the evening and night when the air after a sunny day is warmer than that just above a rapidly cooling ground and there is little wind to mix up these layers.

My first practical experience of this was one April when spraying plots. Spray opportunities were rare and we had to take the opportunity to spray at dusk. The day had been warm and sunny but windy. Towards dusk the wind dropped completely and so we sprayed. As I finished the final plot, I turned round to see some of the spray just hovering above it. What proportion I’m not sure but the treatment worked. However, even a small proportion of the spray moving elsewhere is not desirable.

The largest incident in the UK of inversion causing problems with spray drift was in 1979. Brittox, a product mix of bromoxynil, ioxynil and mecoprop esters, dominated spring broad-leaved weed control in cereals. Again it was a difficult spring for spraying and opportunities to do so were limited to late evening and early morning. The result was widespread damage to oilseed rape. On many occasions the oilseed rape in the adjoining field was untouched but a rape crop further away in the same direction could have discrete patches of damage. This eventually was pinned down to vapour of the mecoprop ester being ‘trapped’ by inversion and moving above the adjoining crop before coming down on a crop further away.Wild melons in Australia

There were two implications arising from these experiences. Firstly, esters of mecoprop were withdrawn and replaced by the less volatile salt formulations. Secondly, the enthusiasm for spraying at night came to an abrupt halt. Tramlines had been introduced in the 1970s and after a few difficult springs, many farmers were contemplating using them to guide the spraying operation at night in order to take advantage of low wind conditions. However, the implicit danger from inversion meant that the problems of spray drift could be higher than when spraying in windier conditions during the day.

The UK is less prone to inversion than some other countries. A few years ago I was travelling with a crop consultant in Australia when his phone rang. A farmer wanted to know how to kill wild melons (they are inedible) in the summer fallow period. He wanted an alternative to glyphosate and the initial advice was 2-4,D. However, almost as an afterthought, the consultant asked how far it was between the paddock (field!) to be sprayed and the nearest vineyard. Apparently, at that time of the year, there had to be a buffer area of 35 kms (yes 35 kms!) between spraying 2-4,D and vineyards. Contamination of vineyards (and potentially wine) by herbicide spray drift in inversion conditions remains a major issue in Australia.

The farmer wanted to kill the wild melons and other green vegetation because hWind erosion near Melbourne, Australiae was trying to store as much water as possible in the soil to maximise the supply to the autumn sown crops. When I first worked in Australia there were two schools of thought on this issue. The first, and the one which now prevails, is that all vegetation between the harvest of one crop and the sowing of the next should be destroyed using herbicides and the previous crop stubble left undisturbed to prevent wind erosion. The alternative traditional approach had been to cultivate regularly to a shallow depth. The argument for that was not just to prevent vegetation from establishing but also to stop capillary flow of water to the surface layers.

The second view has not only been proved inferior, in terms of water storage in the soil, but also it encourages frightening levels of wind erosion. I remember sitting in a plane at Melbourne Airport just over 10 years ago after witnessing a huge amount of cultivation and consequential wind erosion the day before. The amount of red dust in the air was drowning out much of the daylight and I was genuinely concerned that the jet engines would be blocked. After that a sprinkling of Saharan dust seems trivial.

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In science we trust

Posted on 24/03/2014 by Jim Orson

The Cambridge Science Festival is an amazing event. Over a fortnight there are hundreds of events on all aspects of science. Many of them have very catchy titles and appear extremely interesting and it’s clear that quite a few are aimed at children, including NIAB's own stand in the Plant Science Marquee talking about roots and shoots (see picture)! What a shame that I might stand out if I try one of these events.NIAB at the Cambridge Science Festival 2014

Last Saturday I attended a panel discussion (for adults) on the publication and communication of science. I was the oldest person in the 200 plus audience! The peer review system, where the paper is checked before publication by two or three other scientists, has been the established method for around 300 years for trying to ensure the integrity of science. Generally it’s stood the test of time well but it’s certainly not perfect. For the author it can lead to frustration, particular when the reviewers, usually anonymous, provide conflicting advice and comments. Then there are the re-writes to endure.

However, once through this process, the author can proudly say that he or she has a peer reviewed paper. There’s a hierarchy of journals in which to publish and scientists aim to submit papers to so-called high impact publications that only include the best of science. Down the pecking order are numerous journals that will have peer reviewed papers but there is a suspicion that some appoint reviewers who are less than forensic and who share the same views as the author.

A few years ago, a peer reviewed journal published a paper saying that organic agriculture produced similar or higher yields than conventional agriculture and could easily feed the world. It claimed to be a review of all relevant papers where organic and conventional systems were compared. The organic movement was triumphant. It must be true, they said, because it is in a peer reviewed paper.

The conclusions of this paper were a shock to anyone who had experience of the relative production levels of the two systems and prompted an American researcher to check the sources of information used in this review. His findings were shocking.

Over 100 of the papers included in the review described only a comparison between different conventional systems and not a comparison between organic and conventional systems. Also organic yields were misreported and false comparisons were made to unrepresentatively low conventional yields. Where reasonable organic yields were achieved they were counted 2, 3, even 5 times by citing different papers that referenced the same data. Finally, favourable and unverifiable “studies” from biased sources were given equal weight to rigorous studies. I must admit that when I read this critique, my faith in the peer review system plummeted.

There has also been a recent paper suggesting that GM ‘causes cancer’ and this has had to be withdrawn because of weaknesses in the peer review system of the journal.

Trust in science is absolutely vital.  The panel discussion I attended pointed towards a way that increases trust. Not surprisingly, it involves the dramatic innovation that has occurred since the peer review system started 300 years ago - the Internet.

The panel predicted that science will slowly move to a system something approximately along the lines of the following: the draft paper is submitted to a journal and reviewers, perhaps not anonymously this time, are appointed; and then the draft paper, together with the reviewers’ comments, will then appear on the journal’s website plus the data generated in the project, for anyone to review and comment on. 

This whole process could take a year before a final paper script is agreed.  Such an approach would result in the non-publication of the examples that I have previously quoted.

The same approach should now be contemplated by Defra and the UK levy organisations. Recently I have aired my misgivings on the conclusions of the Defra project NT26 where the efficacy of ammonium nitrate and urea were compared (‘Up in the air’).

I feel that a more open discussion should have taken place before the final conclusions were widely promulgated. The primary question should have been why the project concluded that the nitrogen in urea was on average 20% less efficiently taken up by the crop than that in ammonium nitrate, and yet a major review of UK trials’ data, in a peer reviewed journal in the 1990s, suggested that the difference was 3.5%. I also have concerns with the lack of open debate about some of the conclusions in some levy-funded reports.

I think that the era of improved electronic communications will mean that the trend towards more openness and greater transparency will prove unstoppable and should lead us to say with more confidence that in science we trust.

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Where are the birdies?

Posted on 16/03/2014 by Jim Orson

As soon as spring gathers pace the trite rhyme ‘spring has sprung, the grass is ris, I wonders where the birdies is?’ comes into my mind (much to the annoyance of our middle daughter Emily). This year it has more relevance because the numbers of birds in our central Cambridge garden are the lowest I can remember. This is an unexpected observation after such a warm winter when there was plenty of bird food available. The berries in the garden are almost untouched.

The numbers have been falling for years whilst the numbers of magpies and hawks have increased. There is a history of bird egg shells on the lawn and I’ve witnessed hawks hunting. However, the number of magpies has fallen locally over the last couple of years, possibly because they were running out of victims’ nests and have gone elsewhere.

I am not alone with these observations and neighbours are questioning why they are feeding birds. This raises the possibility that success in encouraging bird numbers should be measured not by their numbers but by the prevalence of their enemies, such as magpies and hawks. On this basis, the measures that have been taken to increase birds locally over the last few decades have been a great success!

On farms there are additional hazards for ground nesting birds; these include badgers. They commonly hoover up eggs and chicks in the areas established to provide habitat for ground-nesting birds and in nearby skylark plots in crops. We all know in which direction badger numbers are going.

However, I do recognise that changes in arable agriculture, which have resulted in a dramatic increase in food production, have contributed to the fall in farmland birds. One generally recognised reason was the switch from spring to winter cropping in the 1970s and 1980s. Spring cereals provided a habitat for some farmland birds and the weeds in the crop were a source of food, either as hosts to insects and/or as seed.

The trend in some areas is now towards more spring cropping because of black-grass resistance to herbicides.  So, logically, should this be good for farmland birds? It may be helpful but the management of spring cereals is not what it was forty years ago.

In the 1960s and 1970s, the land was ploughed for spring barley after the winter cereals were sown in mid-October.   It was a steady winter job. The stubbles being ploughed also had recently shed crop and weed seeds on the soil surface. So birds like the skylark had large areas to rest in and had a food source away from field edges. This is no longer true with the land being prepared for spring cereals earlier in the autumn, when soil conditions are generally drier, and improved harvesting techniques and cleaner crops meaning that there is less crop and weed seed around.

In addition, spring cereals are now sown a lot earlier, as soon as conditions are suitable after mid-November, and higher seed rates are used where there is a requirement to compete with black-grass. Generally more nitrogen is now being applied although some heavy-land farmers have been adopting modest doses in order to produce malting quality spring barley. This all means that the relatively open spring cereal crops, suitable habitats for the later clutches of skylarks, are now less likely to occur. In addition, the standard of weed control is now higher than it was a few decades ago. Some annual broad-leaved weed species that tend to emerge in the spring are particularly beneficial to farmland birds, e.g. knotgrass and fat hen. However, in situations where spring cereals are being adopted because of black-grass, the soil seed bank will be largely devoid of these species after many years of winter cropping.

This all suggests that spring cereals will not provide the habitat and food for birds that were provided in the 1960s and 1970s. However, it may be that I am being unduly pessimistic.

There are a number of other trite rhymes that come into my head on occasions (no comments please!). One is ‘the bleedin’ sparrer’ which was obviously written in the days when sparrow hawks were controlled. Sparrow numbers have fallen dramatically over the last few years, probably due to a number of reasons including more predation, less hay-fed livestock and excluding birds from agricultural buildings. There was one statistician who even found a relationship between the increasing adoption of lead-free petrol and the decreasing number of sparrows. I have commented many times about scientists putting lines through charts and then believing the line represents the truth; this must be a prime example where great care is needed in the interpretation.

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Winning is everything?

Posted on 10/03/2014 by Jim Orson

Sainsbury’s was selling snow shovels at a 25% discount today so I have to assume that winter is over. The rush on the land is accelerating and as always it will be a busy spring season with multiple passes of fertilisers and pesticides in each field.

I’m developing the view that the current debate about funding elite sport is an allegory for the approach we take to crop management. It can be argued that elite sport and arable agriculture are both aimed specifically at being successful against international competition rather than establishing a sounder (I am trying to avoid the word ‘sustainable’) base.British Basketball v Spain

The debate in sport is about basketball losing its funding from UK Sport because it’s unlikely to get medals at the 2016 and 2020 Olympics. This is despite the GB basketball team losing to the eventual bronze medallists by the narrowest of margins in London 2012. This decision is in contrast to the increase in funding for some less inclusive and less popular sports.  The question being asked is whether elite sport is just about Olympic medals. Basketball is much more popular than some of the funded elite sports, particularly so in the inner cities where it can transform the lives of teenagers.

The equivalent question in arable agriculture is whether it is all about increasing yields and high short-term financial margins. Certainly projects or initiatives to increase yields attract a lot of attention and are followed with great interest in the press. I still clearly remember a lecture in the late 1970s at which a plant physiologist explained the path towards higher cereal yields. It was all the more pleasurable because I had been in a university cross-country team with him and it was good to catch up, in more than one way, as he always beat me! During our conversation he said that the then current developments would lead to higher wheat yields and it was only a few years later, in 1984, that we achieved yields that were far higher than those of our dreams a few years earlier.

This was all part of a process that took the UK from being a producer of just over four million tonnes of wheat in 1970 to not only supplying our home market, but also exporting over four million tonnes by 1990.  This remarkable growth in production was a combination of both a significant increase in the area of wheat and a significant increase in yields.

However, as I have written before, there are now no imminent developments that will lead to significantly higher on-farm yields. It is more likely, in the short term at least, that we may not be able to maintain such high levels of cereal production partly because many farmers are having to replace some winter wheat with spring cereals. The main reasons for this are pesticide resistance, removal of pesticides from the market and more regularly occurring extreme weather events. It seems that our quest to optimise margins in the past has resulted in pesticide resistance that is compromising our current productivity.

A further reminder of this issue was a discussion that I had with some leading researchers last week. I was hoping that they would tell me that we should not be concerned about fungicide resistance because we would soon get disease resistant cereal varieties. However, they said that this is unlikely and that what the industry should be doing is reducing the number of fungicide applications in wheat to two in the season. This could be achieved partly by choosing varieties with reasonable all-round disease resistance.

However, this approach is rather pie-in-the-sky in the cold reality of having to survive financially. It is the crux of the problem; in order to compete internationally UK farmers have been forced, almost knowingly, into practices that they suspected would lead to problems.  What happened to Atlantis is a prime example. The threat of black-grass resistance was recognised before its commercial introduction and warnings of over-reliance on it were hard to avoid. However, because of a lack of alternatives for the control of high weed populations, the inevitable occurred.

So elite sport funding and arable farming are very similar in respect that competing successfully with international competition is essential to keep the coffers flowing. The difference is that in the recent past, in order for arable farming to survive financially, we may have reduced our ability to compete in the future.

Interestingly, the same has occurred for some of our international competitors and so the net result is likely to be felt in the consumers’ pockets. European producers are particularly hampered by the new pesticide registration requirements and the rather smug view of many politicians and bureaucrats that food supplies will be easily available without the aid of new technologies, such as genetic modification (GM). There have also been publicly expressed concerns over other new scientific developments that offer increased productivity in the medium and long-term. It seems that there is a part of our society that wants science taken out of agriculture. The net result could easily be increases in food prices that will dwarf any potential savings on snow shovels.

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Posted on 27/02/2014 by Jim Orson

Last week I went to the Defra offices in London for a meeting. Whilst walking to Cambridge railway station I was reminded of the changes that have occurred on that route over the past thirty years.

Halfway to the station I passed the former site of a large and extensive Ministry of Agriculture (MAFF) office. Like many MAFF offices it was previously a hospital for those wounded in World War II. The buildings were thrown up and made desperately poor offices. I was working there when the then Minister of Agriculture, John Selwyn Gummer visited and apologised for the working conditions. The site is now a very modern housing development.

Things have changed at the railway station as well. In 1984 it had two ticket windows and now it has six plus self-service machines, although these are still not enough to cope with peak demand. Close to the station was a RHM mill that in its latter years milled Soissons wheat for baguette flour; the smell was glorious. That site is also now a very modern housing development.

There have been big changes in the places in London where I’ve attended meetings. In the 1980s, MAFF occupied three substantial buildings in London and the Department of the Environment occupied three tower blocks. As the joint department (Defra) they are now squeezed into one of the former MAFF buildings. Few have their own offices and most work in rooms resembling call centres.

Changes have been as significant or even more significant in arable agriculture over the last thirty years. 1984 was the year of the great breakthrough in wheat yields and over the following twenty years many farmers strove but failed to match that yield. In fact, the overall approach to wheat growing has changed little over the last thirty years. The big changes have been in the size of arable enterprises and the labour and machinery costs.

I was recently in one of the university libraries (this particular one has not physically changed at all over the last thirty years!) and read the annual Farming in the Eastern Counties reports based on the farm business surveys carried out by the University. Starting with the 1984 report, I worked forward to 2004. There was a national re-organisation of surveys in 2005 and the type and format of data in the reports were changed. However, the trends in labour and machinery costs between 1984 and 2004 were intriguing.

Labour and machinery costs remained remarkably stable over that period despite the Consumer Price Index increasing by 85% over the same period. On mainly cereal farms in the eastern counties, the labour cost per hectare was £102 in 1984 and it was £102 in 2004. Machinery costs were £199/ha in 1984 and £165/ha in 2004. The cost of the two together rose from £301/ha in 1984 to £345/ha in 1997 but with the subsequent bad years fell to £266 in 2004. This is not far from the target of £250/ha set by farm business and machinery advisers at the end of the last millennium.

As far as I can ascertain from the more recent data, the costs have increased a little over the last few years as farmers have re-equipped. However, they still do not appear to exceed the joint total of 1984.    

These cost trends reflect an enormous increase in efficiency based on the benefits of scale and access to good and reliable crop protection. The latter has enabled a labour and machinery efficient approach to the management of broad-acre crops, including non-plough tillage and the adoption of block cropping, without having to jeopardise unnecessarily the standard of or the cost of crop protection.

As I mentioned in a blog a few weeks back, this KISS (Keep It Simple Stupid) approach to broad-acre crop management is under threat from pesticide resistance, pesticide product withdrawals (due to higher registration requirements) and perhaps extreme weather patterns. In addition, the ‘three crop rule’ may well reduce the efficiency of labour and machinery use on some blocks of land, particularly those under short term tenancy and contract farming agreements.

So as in all parts of our lives things are not what they used to be. Change and adaptation will always be required.

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