NIAB - National Institute of Agricultural Botany

Orson's Oracle

Disrupting what?

Posted on 22/04/2013 by Jim Orson

Many of us have got by until now without having to worry about endocrine disruption. Well, I’m afraid that over the next couple of years we’ll be made only too aware of the subject. The fall-out from this issue could result in reduced EU food production and the inability to grow commercially some vegetable crops in the UK and possibly the EU. For the record, endocrine disruptors are chemicals that interfere with the endocrine (or hormone system) in animals, including humans.

The recent EU pesticide regulations introduced certain hazard cut-off criteria. Failure to meet these criteria will result in the pesticide being withdrawn whatever the level of risk. Many scientists consider that assessments based on hazard rather than risk is going further down the slippery slope where prejudice rather than science becomes the basis of decision-making. The introduction of hazard cut-off criteria for endocrine disruption is a further example of this.

First of all, how endocrine disruption is assessed and cut-off criteria are set were not clear when the new registration system was introduced in 2012. A more precise assessment and setting of the hazard cut-off criteria is expected by the end of this year. This does not sound good law-making to me; passing a regulation with unclear criteria and hence with unknown consequences.

Secondly, the EU regulators seem to be sanguine about some more obvious endocrine disruptors that continue to be used without question. What I am talking about here is that much of the endocrine disruption in the environment is a result of the use of the contraceptive pill. However, as far as I can understand, this is seen by the EU regulators as part of the natural background of endocrine disruption. I’m not sure of the logic as surely these pills are made in a chemical factory just like pesticides.

The level of debate over this issue will start to increase as the time for decision making approaches. This debate will be stoked by a clearer picture of which pesticides may have to be withdrawn because of the hazard cut-off criteria. 

CRD, the UK pesticide regulation directorate, produced a possible list a couple of years ago which included key triazole fungicides and some pesticides essential for the production of ‘minor’ but important crops, including many green vegetables. There are currently other studies being carried out.  

Naturally, the impact on food production will depend on the final agreement on setting the level of the hazard cut-off criteria. It is now clear that any definition is likely to be damaging to agricultural production and there is the possibility that the productivity of the industry could be severely curtailed.

Whatever the final agreement, there needs to be an assessment of what is the likely impact of setting these criteria on food production. This seems absolutely essential when, as in this case, a regulation is introduced without knowing the true implications of its impact. Also, in the quest for true transparency, it would be illuminating to know what is considered to be the current impact of endocrine disruption on human health and the environment.

In addition, the industry would be particularly interested to know the additional risk posed by pesticide usage over and above the ‘natural background’ level of endocrine disruptors, which not only include the contraceptive pill but also chemicals naturally found in plants.

I understand that EU law states that assessments are made to estimate the likely impact of new directives and regulations. Because of the possible effect on EU food production and food prices, such an impact assessment on the implications of setting the hazard cut-off criteria has to be done openly and transparently.

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A fallow year

Posted on 14/04/2013 by Jim Orson

There is an increasing acceptance that we’re going to see a lot of land in true fallow this summer. This is because in many situations there is little prospect that a profitable crop can now be sown. Consequently, we’ve been receiving queries on the management of a true fallow.

From my point of view, the introduction of glyphosate was a ‘game-changer’ in terms of fallow management. There is now no longer a need to keep moving the soil to stop weeds establishing. In the past, fallows were often adopted in order to control perennial weeds. Repeated cultivations were timed to try to exhaust their perreniating organs, such as the rhizomes of common couch. This is now not necessary and so an awful lot of diesel and earthworms can be saved and more emphasis can be placed on using fallows to improve soil structure.

It is very doubtful that repeated cultivations during the late spring and summer will contribute much to reducing the grass weed, including black-grass, seed burden in the soil. Perhaps the initial cultivation, if it is carried out in April, may stimulate some black-grass seed to germinate and so there needs to be some knowledge as to where the seed bank may lie.

If it is suspected that much of the seed is in the upper layers of the soil, the choices are to have a shallow initial cultivation to try to stimulate germination or, in order to take advantage of more time being available, to plough them down to a depth from which they cannot emerge. However, all this may be theoretical chat as the majority of the fields in question have already been cultivated and the black-grass weed has been dispersed throughout the surface layers. 

It may be more important to prepare a stale seedbed well before the next crop is sown in the autumn. This may prove worthwhile provided that there is some moisture to support germination. 

So the main objectives of a fallow are to improve soil structure and to provide a break from cropping. In my opinion, a cover crop has to be sown to improve soil structure. Not only will it pump out water and hopefully subject the soil to wetting and drying cycles but the vegetable matter produced, particularly the roots, will result in a ‘living soil’. Using a cover crop to dry the soil may be essential if sub-soiling is required in order to repair soil damage. In addition, provided that there is plant cover in August a cover crop will prevent wheat bulb flies laying eggs.

So an investment in a cover crop is worthwhile. This view is supported by a project that The Arable Group, now NIAB TAG, carried out for HGCA a few years ago (HGCA Project Report No 414). In this project, the second wheat in a ‘fallow wheat: fallow wheat’ rotation yielded 1 t/ha less than the second wheat in a ‘mustard; wheat; mustard; wheat’ rotation.

Mustard is often the first choice for a fallow. However, this may not be a wise choice on farms that have a high proportion of oilseed rape in the rotation. This is because mustard is botanically similar to oilseed rape and may share the same root diseases that have been identified as being a likely contributory cause of reduced yields associated with tight rotations of the oilseed rape crop. The problem is that we do not know if mustard will increase the level of these root diseases in the soil, particularly as it will be in the ground for such a short time.

The alternatives to mustard may be a grassy crop such as rye, which does not host take-all, or even a short season rye-grass. A lot will depend on seed supply and the farm rotation. However, whatever the choice, it is important that the seed from the cover crop is not allowed to shed and become a weed in its own right. Also, make sure that any black-grass or other pernicious weeds are prevented from shedding viable seeds.  

Let us hope that this year is unusual and that in the future we are not forced by the weather to have fallows.  However, it is worth writing down your experiences with fallow crops this year as you never know what the future will bring.

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It’s the weather stupid

Posted on 08/04/2013 by Jim Orson

There’s always a lot of interest from other countries as to how we achieve our high winter wheat yields. In some parts of the world there is a firm belief that if they use inputs in a similar way to us then they would get similar yields. I have to explain to them, as politely and as politically as I can, that it is our weather and soils that generate our high yield potential but to realise that potential we have to use a fair number of inputs.Winter wheat

I am sure that I must have said this in an earlier blog but the three countries with the highest wheat yields are islands. Top yielding, by quite a way, is Ireland with New Zealand and the UK vying for second place.

The sea surrounding islands help to regulate their climate which results in, at their latitudes, moderate winters and moderate summers; just right for wheat. So the crop has a long time (in terms of both time and heat units) to develop and a long time to ripen. The latter is critical as the crop will ripen over a given number of day degrees of temperature and the more solar radiation that can be absorbed by the crop over that time the better, provided that green leaf area is retained and water is also available.

But things can go wrong, as we all too easily recognise. For instance, when I was in New Zealand last December the wheat was just flowering and there was a huge amount of solar radiation available to the crop i.e. the weather was far sunnier than normal.

However, the crop at flowering is susceptible to heat stress, particularly when soil moisture may be limited. On one day the weather was not only hot but there was also a very dry wind. The locals estimated that there could have been a potential loss of 7-8 mm of water on that one day. It was a recipe for the cooling system of the crop to break down. It was weather similar to this throughout flowering that perhaps resulted in their irrigated wheat yields this harvest not reaching the potential that would have been assumed from the amount of solar radiation available during ripening.

The French have a word for heat damaging yield prospects during grain ripening, particularly at flowering. They call this process ‘echaudage’ and it’s estimated that once temperatures exceed 250C over two days (and with warm nights) there will be a negative impact on yield. 

I remember personally experiencing such an event; I think it was in 1992. I was walking through a wheat variety trial during very hot weather. The UK wheat varieties were at flowering and visibly suffering in the heat. The French variety Soissons was past flowering and was not visibly suffering from the heat. That year was the making of Soissons with it experiencing high yields relative to the UK varieties. That short burst of very hot weather was perhaps instrumental in it making the Recommended List.

The ripening period is the glory bit of the life cycle of winter wheat. The role of the earlier growth stages is to provide a crop structure that provides sufficient capacity (known as the sink) to be filled by net photosynthesis (known as the source) during grain fill. Typically, the size of the sink is not a problem, as demonstrated by UK varieties yielding 16 t/ha in New Zealand. However, there could be a problem in the size of the sink in late sown wheat crops this season. Late sowing and the lack of spring growth may well result in fewer potential grains than necessary in order to achieve high yields, however great the weather may be during grain fill.

In simplistic terms, over the autumn and winter accumulated temperature is the main driver of growth and development in winter wheat but day length also has a very significant influence on development from the start of rapid growth in the spring. This is why all winter wheat crops on a farm will ripen over a relatively short time period despite their date of drilling. This year there has been a decided lack of heat units experienced by late drilled crops and soon, day length will become more influential and these crops will rush through their growth stages. The collateral damage from this scenario is a poor crop structure for achieving high yields, particularly a lack of grain sites.  As always, ‘it’s the weather stupid’.   

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Moving on

Posted on 01/04/2013 by Jim Orson

We recently spent a few days clearing a house of my wife’s mother’s possessions. It was both an emotional and sobering experience. Memories and mementos of a long and eventful life were packed into a few cardboard boxes in the back of a borrowed transit van.

Whilst on the long drive back I thought that the agricultural industry has also had similar experiences over the last few decades. All those research establishments and experimental husbandry farms that have been closed down and much of what remained packed into cardboard boxes. In many ways, those who work in research establishments have to expect such change because fundamentally, change is what research is about. However, it is more complicated than that.

In my opinion change can only really be accepted if there is agreement that the current research is no longer necessary or relevant, the knowledge already gained is retained within the research community and the change reflects the most potentially beneficial direction that current research has opened up.

I was working at, rather than for, the Weed Research Organisation in 1983 when its closure was announced. Whilst having enormous sympathy for the members of staff, I admit to thinking at the time that perhaps its days were over. Established before the widespread availability of herbicides, perhaps the problems it was trying to solve had become solvable. I was also comforted by the fact that the key staff members with unique knowledge were to be transferred to other research establishments. However, this was not a true legacy as some of these disciplines have now disappeared from publicly-funded research in the UK. For instance, when I recently needed crucial information on the behaviour of herbicides in dry soils, I had to consult a specialist in Denmark.

Research budgets are tight and there are other demands on the Government’s purse so difficult decisions have to be taken. I personally agree with the emphasis on genomic research over the last few years but there is a danger of other critically important disciplines dropping by the wayside. Resistance to pesticides means that decisions to close such establishments as the Weed Research Organisation, a decision which may have seemed logical at the time, should not be viewed as the final say on a research discipline. Perhaps more academic research is now required on the behaviour of pesticides in the soil because of the challenge we face from pesticide movement to water.

People still fondly refer back to the role of ADAS during the 1970s and 1980s in transferring publicly-funded research into practice. I was an ADAS field adviser for most of those two decades and I am not so convinced about our achievements. Much of the publicly-funded research in the 1970s and 1980s was applied research, the most relevant of which could easily be adopted. That is no longer the case and so the challenges today are on a different scale.

There are different approaches to packaging and delivering knowledge. In terms of genomics, the packaging is the crop variety that is sold to the farmer. NIAB is playing a central role in packaging the knowledge gained in publically funded genomic research into breeding lines for commercial plant breeders. In the parlance, it is called pre-breeding.    In a similar vein, pesticide products are the simply adopted result of very complex privately-funded research.

It is the bits of publicly-funded and indeed industry (including levy) funded research that do not result in a product but can be used to benefit agriculture that are potentially most difficult to transfer into practice. Where the advantages are so obvious and the cost and risk of adoption is low then there is not really a problem.

The difficulty lies where there is a significant cost and/or risk of adopting something which may give less than stellar returns. In this case, it is up to those in research and its transfer to be honest and open when encountering these potential blocks to adoption rather than to moan that a couple of PowerPoint based talks have not persuaded the industry to adopt their pet project.

By its very nature, not all research is successful and the results of many projects are not at a stage that where they would lead to changes in farm decision making. However, all good relevant research that is honestly interpreted can be a stepping-stone for the industry.


Come along to the NIAB Cambridge Open Day on Tuesday 25 June to see pre-breeding research in action alongside an afternoon of seminars, indoor exhibits, and field demonstrations. Now at our new Park Farm demonstration site at Histon with expertise in plant breeding and pathology, seed testing and variety evaluation, as well as agronomic research, training and farm advice. Members-only variety demonstration tours will be available in the morning.

Three months free

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Can you take the risk of not using it?

Posted on 22/03/2013 by Jim Orson

There were a series of extremely mild winters when I was working as an ADAS field adviser in coastal Essex in the 1970s. Perhaps as a result of these weather conditions, newly emerged peas were often infested with thrips and the debate was whether or not they should be controlled. So I organised a field trial to test a range of different insecticides. Every one of the six or seven insecticides tested gave a 3% yield ‘response’; remarkably consistent results.

There was no chance that such a low response would be statistically significant, but if the differences were real then it was just about worth spraying the crop, particularly if the insecticide could be tank-mixed with a herbicide being applied at the same time. The ADAS entomologists said that as the treated yields were not statistically higher than the untreated yields there was no yield response.  The trial was repeated the following year because the results were so debatable.Cheap agchem can

The same trial the following year gave the same results, with a 3% yield response to every insecticide tested.  The discussions over the practical implications of the results led to a big falling out between me and the entomologists. My interpretation was that because every insecticide tested had consistently given a small increase in two separate years then there was a response and it might be worth farmers spraying. The entomologists stuck to their guns and said that there was no statistically significant yield response and so infested crops should not be sprayed.

The industry continues to be faced with similar statistical ‘challenges’. When is a possibly cost-effective benefit real if the response to the input is not statistically significant? This question is more likely to be asked where the cost of the input is very low relative to the monetary value of a statistically significant response.

It is a question that is now very pertinent because of the plethora of, let us call them, ‘plant tonics’ that farmers are being encouraged to buy this spring to apply to backward crops. On one hand, they can be expensive in the context of their declared contents. On the other hand, they are very cheap compared to pesticides because they have not gone through a regulatory process. And a worthwhile response from their use is way below the level of that which can be recorded as statistically significant in a trial.  For information, in wheat a yield response of 5% or more is typically required to be statistically significant.

How do we deal with this situation? Some say that the current methods of analysing experiments are not up to the job.  However, eminent statisticians have concurred that there are no alternative techniques that can be adopted to resolve this impasse.

One answer may be to modify the current statistical approach which typically sets the probability of a response being real at 95%. This means that there is a 95% probability that the response is real and a 5% probability that the response has occurred by chance. 

Perhaps these odds can be changed when the cost of the input is very low compared to the monetary value of a statistically significant response. I’m sure that, in this situation, many farmers would accept the lower odds, such as a 75% probability that the response is real and a 25% probability that the response has occurred by chance. This would reduce the size of the response required to get a significant difference. As far as I’m concerned, this is a perfectly valid approach provided that the probability of the analysis is openly declared.

In my opinion, a higher number of trials have to be carried out in situations where possible responses to cheap inputs are difficult to assess with confidence. This can then bring in the common-sense element of judging the consistency of response over a greater number of sites. 

It can also enable a cross-site analysis to be done on a greater number of sites which will improve the chances of getting a statistical difference at the more conventional probability levels. What really is not acceptable is an interpretation that involves cherry-picking the results of one or two trials where there are small cost-effective responses that may be significant at the 75% or even the 95% probability level and ignoring all the other results where there are no responses or ‘negative’ responses. As always, common sense rules.

The cost of such ‘plant tonics’ when multiplied over a few hundred hectares is not inconsiderable. So next time someone tries to sell you something on the basis that ‘it is so cheap why take the risk of not using it?’ you know what questions to ask about the evidence you need to see to be persuaded. Also, dig around for independent sources of information; there may be more around than you think.   

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