NIAB - National Institute of Agricultural Botany

Orson's Oracle


Posted on 14/03/2013 by Jim Orson

I read a great quote the other day:

Insanity is a perfectly rational adjustment to an insane world
Scottish psychologist R D Laing

Quotes like these have an immediate impression if you can apply them to something you have just experienced. The fact was that I had just previously read that the Serbian Minister of Agriculture had apparently accused pro-GM groups (?) of contaminating a consignment of conventionally grown maize from his country with mycotoxins so that it failed to meet marketing standards.  

This did seem to me to mirror the insanity that is now associated with GM. Rational thought and good common sense has gone out of the window. There are now 170 million hectares of GM crops grown around the world annually and no one has caught even a sneeze from their cultivation. So if you do oppose them what do you do?  Perhaps make statements like those attributed to the Serbian Minister of Agriculture.

As he must have scientific advisers, he would have known that he was on weak ground about possible mycotoxin levels in conventionally grown maize. This may explain such a dramatic statement. GM Bt maize for the control of insect borer pests typically has lower levels of mycotoxins, in particular fumonisin and aflatoxin. This is because the fungi that cause the toxins can grow quickly along the tunnels in the maize plant caused by the borers. The sheer efficiency of control of the modified maize means that there are no, or fewer, tunnels. Not only are these mycotoxins toxic but they also inhibit the ethanol production process from maize. Hence, the ethanol production plants prefer to process Bt maize rather than conventional maize.Forage maize

There is a small part of Europe that grows Bt maize. The area of this GM crop is steadily increasing in Spain where it is grown for animal feed. I met some Spanish agronomists last year and they said that at one time the GM maize had to be segregated from conventional maize along the chain to the animal feed mills. Now, with its increasing dominance, it doesn’t have to be segregated. They also said that the feed mills prefer it because it has significantly lower levels of mycotoxins than conventionally grown maize.

I know that the so-called green groups in Spain have thrown everything, including the kitchen sink, at Bt maize. Each accusation has been patiently followed up by scientific study and found to be groundless.

In my (insane?) opinion, the history of the anti-GM movement is littered with ‘ill-judged’ statements. Some of these have been mere mischief-making and some may be the cause of avoidable human misery. The prime example of this is the apparent hatred of golden rice (genetically modified to have a high Vitamin D content) that offers so much in reducing the occurrence of blindness in hundreds of thousands of children in some parts of the world. I have written about this before but it is so important that it is worth another reference.  The anti-GM movement says that this is a cynical exercise to achieve acceptability of GMs. I have to ask who the cynical ones in this story are; those non-profit making organisations that developed it and are trying to get it introduced or those (often) multi-million pound/dollar international so-called green groups who rely on a good scare or two to keep the subscriptions coming through the letterbox?

Institutional amnesia or downright rejection of uncomfortable truths is a major concern in today’s society as the issues around Stafford Hospital clearly demonstrate. It may have always been thus. However, you must ignore everything I say: I may be completely bonkers.

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Foundation of the horsemeat scandal

Posted on 07/03/2013 by Jim Orson

Did you know that the recent horsemeat scandal was a result of the wet summer of 1845? Well, there is a link but you may find it rather tenuous.

The weather in the summer of 1845 was awful; cold and extremely wet. It all sounds horribly familiar. Not only was the weather bad in Britain but also in the rest of Northern Europe, which at that time was our main trading area for food. The Irish had their potato famine caused by blight and there were general food shortages across Europe. In Britain, the high price of food led to the repeal of the Corn Laws in 1846 and eventually opened us up to inter-continental competition.

The Corn Laws, in various forms, had been in place for centuries. The aim was to regulate movements of wheat to avoid the huge price volatility that occurred between seasons of plenty and seasons of shortage. They changed over time to adjust for improving transport systems between various parts of Britain and with Northern Europe and at one stage included storage of grain in years of plenty. So intervention stores are an old idea!Corn Laws

The Corn Laws were also open to abuse, and monarchs and parliaments tried to use them to raise money to fund their wars. From 1815 onwards they were used mainly to protect British agriculture by means of import duties. There was support for this, even from the free marketeers of the time, who thought it inconceivable that we should not be self-reliant in food production. However, the Government had to repeal them after the food shortages and high prices of 1845. As was reported at the time - “the rain rained away the Corn Laws”.

Their repeal did not have an immediate negative impact on British agriculture. A rapidly expanding non-rural population meant that prices remained relatively high and the age of science began to impact on production, particularly the use of fertilisers and machinery. In addition, the ability to mass-produce drainage tiles resulted in an enormous investment in land drainage. Between 1850 and 1880 the banks lent British farmers £12 million for land drainage, worth about £12 billion in today’s money.

However, some of the technology that aided this ‘Golden Age’ of farming presented new challenges. Steam power, which was beginning to help us to till the land, was also used in opening up the prairies. Perhaps more importantly, it resulted in faster, more efficient and more economic transport. The opening up of the prairies coupled with better transport systems resulted in a huge increase in cheap imports of wheat from the late 1870s onwards. In Britain during the 1880s wheat imports doubled and prices halved. Our high cost systems that were dependent on fertilisers to maintain fertility could not compete with large-scale farming that relied on the residual fertility from ploughing out the prairies. The so-called ‘Golden Age of English Farming’ was over and prices remained depressed until the First World War.

It was not only ‘corn’ that was down; ‘horn’ also suffered from competition. What prompted me to write this blog was that I read in The Times the other day that the first refrigerated cargo of lamb left New Zealand on the 15th February 1882, arriving in London on the 24th May. Up until then the New Zealand sheep industry had a problem.  After years of building up stock and achieving self-sufficiency their isolation meant that they had no real means to exploit their potential for lamb production. They had tried canning lamb but this was not a success. However, refrigerated steam ships provided them with an opportunity, which they took with both hands.

So, it can be argued that the wet summer of 1845 resulted in Northern European countries finally accepting that their burgeoning populations could not be fed from their own resources. In the UK the protection offered by the Corn Laws was dropped and the large scale inter-continental food trade started. And you know what that meant; complicated food chains that are obviously open to abuse. I rest my case!

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Making water wetter

Posted on 01/03/2013 by Jim Orson

When the wax finish on your car is still good, rain droplets will ‘bead-up’ and not really wet the surface as they are repelled by the wax. The impermeability of the wax on the car’s body and the surface tension in the rain droplets keep the water from ‘wetting’ the surface. Surface tension can be described as the contractive tendency of the surface of a liquid.

The same can be said for pesticides, particularly those that are water based such as glyphosate and the hormone herbicides.  Water has a higher water surface tension than the oily/waxy layers of the plant surface. Hence, it seems logical that any surfactant (surface acting agents) that reduces surface tension and so enables the spray droplet to spread will improve herbicide performance. Sadly it isn’t as simple as that.  

Reducing surface tension to as low as possible can result in droplets running off the leaf as the droplets coalesce (due to very low surface tension). Some surfactants may reduce surface tension to the point where the spray droplet is spread over such a large area that it dries too quickly, reducing uptake of an active ingredient that may need to be in the semi-liquid state to be absorbed.

So, there is a great danger in the assumption that the better the spread of droplets the better the activity of the pesticide. An additional issue is that having too much surfactant in the sprayed liquid can lead to damage to the plant surface, inhibiting herbicide uptake.

As I said last week (Have we got it?), in experiments the really big benefits of adding the surfactant ethoxylated tallow amine are only recorded at doses that are so low as to give unsatisfactory control, even after its addition. 

Research in France suggests that, even when sprayed in water that is typically marginally harder than anything we get from the tap, the benefits of adding this surfactant for the control of volunteer barley are not really apparent until the doses of the glyphosate 360 g/l formulations tested were reduced to 2.0 l/ha applied in a spray volume of 200 l/ha. The same concentration of surfactants from the formulation would be present in 1.0 l/ha product in a spray volume of 100 l/ha but crucially the actual dose/ha is still halved.

Other French research suggests that the addition of ethoxylated tallow amine surfactants to 1.0 l/ha of a 360 g/l product significantly increases spray retention when applied in a total volume of 150 l/ha.

The issue has moved on over recent years. There are some concerns over the use of ethoxylated tallow amines and many of the most recent formulations contain other surfactants. Alternative surfactants to ethoxylated tallow amine include the ethoxylated rapeseed oil surfactants.

However, some recent German, French and American research suggests that great care needs to be taken to get the right form of these surfactants. This research clearly demonstrates the danger of having a spray solution with too low a surface tension i.e. the droplets spreading too much.  

A German laboratory study identified the most biologically effective spray solution produced from mixing the unformulated glyphosate salt (the active substance) with individual ethoxylated rapeseed oil surfactants chosen from a range that differed in their impact on the surface tension of the spray droplet i.e. their level of ethoxylation. The most biologically effective surfactant was one that only marginally increased the spread of the droplet (when compared to the unformulated glyphosate salt) on easy to wet plants (e.g. chickweed and pansy) but did not increase the droplet spread on difficult to wet plants (e.g. fat-hen).   

rapeseed oil

The improved weed control resulted from minimising the glyphosate ‘footprint’ on the plant surface. This created very small but highly concentrated areas covered by glyphosate. The better biological activity may be attributed to a higher concentration gradient between the drying deposit on the outside of the plant and the xylem and phloem inside the plant.

In this German study, the droplets were applied individually and all were retained by the target plant. However, there have been field trials in France and the US which confirm that rapeseed oils with the same level of ethoxylation as those identified in the German study can be effective formulants or spray additives to some existing glyphosate formulations. The key is that the level of ethoxylation of these rapeseed oils has to be high.  The most effective ethoxylated tallow amine additives are also those with a high level of ethoxylation.

So, the assumption that the most effective pesticide formulations are those that result in the maximum spread or coverage of the plant surface is truly blown by this research on glyphosate. I’m sure that the same must apply to some other pesticides, but of course not all pesticides. It’s the same old message; no one adjuvant is a good partner to all pesticides and certainly, in some cases, at least it’s not worth making water much wetter.    

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Have we “got it”?

Posted on 22/02/2013 by Jim Orson

Thirty years ago I was working as the ADAS liaison officer at the Weed Research Organisation (WRO).  This was one of the first research institutes to be closed; perhaps one reason for that may have been because by that point there was an effective range of selective herbicides in annual crops and, of course, glyphosate was the answer to perennial weeds.  

Prior to glyphosate there was a huge research effort on the cultural control of perennial weeds, notably common couch. So perhaps there may be good cause to revive this organisation if herbicide resistance continues to develop and product withdrawals carry on at the current rate?

One of my duties was to answer phone queries and there was a huge interest in the research being carried out on the use of adjuvants to reduce the dose of Roundup for perennial weeds.  At that time Roundup was priced at a level for the control of perennial weeds and it was accepted that annual weeds would be controlled by paraquat, with or without diquat.   

The price of Roundup in the early 1980s was £12.50/litre, which now equates to around £40.00/litre, so you can appreciate the interest in lowering the dose.  Mind you, the wheat price at the time was about £120/t which is around £375/t in today’s money.

The research at the WRO was partly taken out of context as the adjuvant additives were very significantly increasing the control of couch only at relatively low doses of glyphosate. As doses were increased in order to achieve an effective level of control, with or without the addition of adjuvants, the benefits of their addition became marginal.

I gave a paper at one of the much fabled BCPC Brighton Conferences saying as much and pointing out that in good growing conditions, the effective dose of Roundup could be much reduced even without the additional adjuvants.  Shortly afterwards it became clear that using a lower volume of application often increased the efficacy of low doses, probably due to increasing the concentration in the sprayed solution of the adjuvants that were already in the product formulation.

However, the phone calls kept coming. In those days recommending lower than label doses was viewed as heretical by the industry and I had a difficult path to follow. Nowadays, appropriate doses are commonly used.

There is still an interest in adding adjuvants despite the limited evidence of a significant economic advantage from their adoption and the current low price of glyphosate products. The two originally identified in WRO research were ammonium sulphate and a surfactant (surface acting agent) - ethoxylated amine surfactant. The original research suggested that both should be used with Roundup.

About 10 years ago there was a paper published on the subject by an INRA researcher in France. He confirmed that adjuvant additives were more effective in increasing performance when the dose of a glyphosate product, with or without the additional adjuvants, was so low as to give only about 50% control (of barley in this case). 

He added the same adjuvants as identified by the WRO and concluded that it was only worth considering using ammonium sulphate if the water was very hard; i.e. contained more than 200 parts per million (ppm or mg/l) calcium.

In less hard water he recorded an advantage from using ethoxylated tallow amine as an additive but it should be noted that he was applying the glyphosate product in a total volume of 200 l/ha. It may be that at lower volumes this advantage would not have been recorded. Finally, the WRO results that adding both adjuvants may give superior control was not confirmed, even where the water was very hard.

The reason for ammonium sulphate only increasing the performance of glyphosate in very hard water is clear.

The herbicidal part of any glyphosate preparation is glyphosate acid but the material is always formulated as a salt because the acid is practically insoluble in water. This is why the glyphosate content of a formulation is declared as acid equivalent (ae) rather than active ingredient (ai). Calcium and magnesium salts in hard water combine with the glyphosate salts and if present in sufficient quantities can effectively block some herbicidal activity. The addition of ammonium sulphate results in the calcium and magnesium binding instead with its sulphate ions, resulting in an effectively higher available dose of glyphosate.

There are few if any tap water sources that have a calcium content above 200 ppm (mg/l) but there may be some other water sources that could exceed this threshold. Your local water company will have a postcode search facility for the calcium content of tap water for your area. This also takes into account the calcium equivalent content of magnesium. Beware that I’m talking about calcium content and not calcium carbonate content, which is 2.5 times more.

So is there an argument to add ethoxylated tallow amines to some formulations? These surfactants are similar to those already in many glyphosate formulations. It is the old story, if there was a simple solution to adding these adjuvants to glyphosate products then we would have “got it” by now. More on this next week.

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Choose trusty sentinels

Posted on 15/02/2013 by Jim Orson

“Use careful watch; choose trusty sentinels”

[Richard III to the Duke of Norfolk]

My father was a farmer, county councillor and history nut. The Leicestershire County Council offices were in the middle of the city and he used the designated car-park at Greyfriars. He would have been tickled pink if he’d known that he’d parked his car over the grave of Richard III. Richard IIII’m sure he must have read the biographies but I’m not sure how he viewed Richard; a bad king or a good king. Modern thinking suggests that he was a good king and Shakespeare, either intentionally or unintentionally, got it wrong. It’s interesting how views change over time.

The same could be said about the views on soils and plant nutrition. It’s easy to assume that soil is just there and a medium for various uses, such as growing crops and burying monarchs. However, as everyone now recognises, it is a living and an enormously complex medium; so complex that we still have only an incomplete understanding.

For instance, some soil scientists have held the view that the amount of soil mineral nitrogen measured in the spring has a dominant influence on the dose of nitrogen to apply to an individual wheat crop but examination of the trial databases doesn’t really support this view. The trials database assembled to help guide deliberations on the content of the most recent edition of RB209 (the Fertiliser Manual) shows that for any given value of measured soil mineral nitrogen, the optimum applied dose of nitrogen for feed wheat can vary by a factor of three. There is a long way to go in improving nitrogen recommendations.

The constancy of the presence of soil has also implied that some of the other guidelines for nutrition advice are also solid and unchallengeable. For instance, the advice in RB209 is to maintain the level of plant available phosphate at Olsen P Index 2.  This seems inviolable and so it comes as a shock to discover that this information was derived largely from only two soil types.

As a result there is an HGCA-funded project that is checking whether Index 2 is the correct soil index to maintain for cereals and oilseed rape over a range of soil types. The project has yet to be completed but the results so far generally suggest that this is correct. However, there have been higher yields on plots at Index 3 in trials on sites where poor soil structure may have inhibited the ability of the crops to scavenge for phosphate.

There is one soil type in the project that isn’t behaving like the others. It’s a Cotswold’s brash soil, where it hasn’t been possible to maintain the high soil indices that were created on the other soil types by using large initial doses of triple superphosphate fertiliser. Here, yields have been maintained by soil indices below 2 but there hasn’t been, so far, responses to the application of fresh phosphate at such low indices. This is probably due to the extremely high levels of calcium in the soil making the phosphate less available to plants as measured by the Olsen P technique used in the laboratories. So after some untangling of the results there may be some specific guidelines for calcareous soils in the next edition of RB209. 

The results of this project confirm that phosphate supply to the soil is not a straightforward process. Freshly applied phosphate remains available to plants for a few months but gradually much of it becomes, at least temporarily, locked up in ‘pools’ that have low availability to plants. However, in most UK well structured soils, at Index 2 the amount in the plant available ‘pools’ is sufficient for unrestricted crop growth even if fresh phosphate is not applied.

This is not the same the world over. In many, if not most Australian soils they have to apply some phosphate on an annual basis because that applied to previous crops is not sufficiently available.

This reminds me of some old correspondence I read when I was working in Australia last year. The letters were between a woman who had married and emigrated to farm in Western Australia in the 1920s and her mother in the UK.  It was really heart-breaking stuff about bringing up an increasing number of children whilst initially living in a tent and then in a very small house (hut).  Added to that was the pain of homesickness (no Skype in those days), the hardships resulting from what nature can throw at you in Australia and the land rights battles with neighbours. However, there was a happy ending of sorts. She came back for a prolonged visit to the UK in 1951 and her son wrote to her whilst she was here. He said that he had been to a local field day and a soil scientist had told him all about the benefits of annual applications of phosphate. This, according to his letter, would result in a golden future for the family. I think you have to be a true romantic to believe that!

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