NIAB - National Institute of Agricultural Botany

Orson's Oracle

Breaking news

Posted on 09/05/2013 by Jim Orson

Breaking news

I have spent the last three weeks on holiday in the USA. This came about because we got tickets for the final practice day and par 3 competition of the US Masters (golf) which is held in Georgia. As a consequence we toured south east USA. There was little farming but an awful lot of swamps in the areas we visited, but we did manage to visit a cotton plantation; fascinating.

There is no doubt that you haven’t visited the NIAB website to read about the holiday of one of its staff. However, whilst we were out there the Boston bombing occurred. This appalling act of terrorism was a severe blow to the American public, and the news was dominated by this tragedy. CNN spent virtually all of its airtime on the subject for the following two weeks, most of it live from a nearby street in Boston. A speaker at the White House correspondents’ dinner said something like ‘CNN likes to cover all angles of a story, in the hope that one of them is correct’.

It was the CNN coverage of the bombing that led me to re-evaluate the meaning of ‘breaking news’. Invariably an interview with yet another witness of the bombing, who said something very similar to the previous witnesses interviewed, was classified as ‘breaking news’ and I’m sure the other news networks did the same.

In fact there is a ‘breaking news’ mentality in all news media including the UK agricultural press. There are plenty of instances where the same story is printed year after year as if it was hot news. Let me give you an example: every year I read that volunteer potatoes on dumps need to be controlled as they are a source of blight.

This is not to demean a valuable advisory message but the breaking news element is that someone new appears to make the statement. However, the sheer familiarity of such reports that are repeated annually results in little scrutiny of what has occurred in previous years or updating of the approach being covered. A good example of this is the annual coverage of canopy management of oilseed rape. The same old coverage occurs annually but there have been a lot of lessons learnt.

First of all, I have to say that OSR canopy management has enormous potential to optimise the nitrogen dose. This is no mean feat when you consider how contrary this crop can bOSR canopy managemente. However, we’re falling short of this potential because of the difficulty in measuring nitrogen in the canopy. Despite the apparent sophistication of the rapid assessment techniques, the errors can be so large as to negate the value of the approach. The only sure way of getting an accurate assessment is the approach taken in the original trials; harvesting all the above ground green area, measuring it and then analysing it for nitrogen content.  I am sure NIAB TAG is not alone, because of the potential reward of an accurate assessment of the optimum nitrogen dose, in trying to shortcut this tedious and expensive approach.

 You may have noted that I’ve not mentioned yield as a potential reward. This is difficult to ascertain because it depends on what you compare canopy-managed OSR with.

If it’s against the same nitrogen dose, but with conventional timings, then the initial trials only recorded a significant yield increase from canopy management in one instance, where it avoided an excessive dose being applied early to a largish canopy.  This resulted in crop lodging. Where lodging was avoided by the use of a triazoles fungicide there was no significant yield advantage from canopy management. And where the comparison was between canopy management and 240 kg N/ha with conventional timings then surprisingly there was still little difference in yields.

This leads me to the conclusion that unless lodging is avoided by canopy management, the overriding reason for its adoption is to optimise nitrogen doses and margins over nitrogen cost. So let’s hope that in the near future there will be some true breaking news on nitrogen for OSR. NIAB TAG has obtained a wealth of data over the last couple of years and I’m sure that soon we will be better able to assess quickly the nitrogen contained in the OSR canopy at the end of the winter.


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The Impatient Optimist

Posted on 30/04/2013 by Jim Orson

A few weeks ago I recorded Bill Gates delivering the Richard Dimbleby lecture at the Royal Institution. It was entitled ‘The Impatient Optimist’ and centred on the efforts of the Bill and Melinda Gates Foundation to reduce child deaths from disease.

The Gates Foundation is huge, worth $US 36 billion. Not all the money has come from Bill Gates; Warren Buffet, the investment guru, has also contributed billions. They come from a long line of great American philanthropists who have given huge amounts of money to society.

I watched the recording of the lecture recently. What was refreshing about Bill Gates’ lecture was that he saw innovation as the key to reducing child deaths from disease. This is in contrast to the hand-wrenching of European society to anything new and innovative. For instance, he sees merit in using GM mosquitoes in order to reduce the transmission of dengue fever and malaria. The great cynics of our society say that this is just an excuse to get GM introduced. But why go to the expense of developing and registering GM mosquitoes if they do not have a potentially useful role? Surely not just for good PR?

As far as I know, there are two types of GM mosquitoes being developed. One approach is to modify mosquitoes to make them sterile, an alternative to irradiating them. They are then released and mate with the local population but of course there are no progeny and so total numbers are reduced. The concern about this approach is that mosquitoes may be an essential component in local ecosystems. So an alternative approach is to modify the mosquitoes so that they do not transmit disease. Large releases will allow local populations to be dominated by these harmless (in terms of disease transmission) mosquitoes.

Whisper it quietly but DDT is still being used in the fight against malaria. It seems sense to me to spend a few pence to spray the inside of a one-room mud-brick house with DDT and kill mosquitoes (and other nasty creepy crawlies) rather than to spend £5 per mosquito net in order to give people an imperfect barrier against insect bites. Now this really sounds like heresy but think about it.Spraying DDT against mosquitos

The problems with DDT arose when it was massively sprayed and slopped all over the place, not when it was used in a targeted way and in quantities just sufficient to rid homes near malarial swamps of mosquitoes. So, as usual, it is how a pesticide is used that is important and not necessarily its potential for harm when used irresponsibly.

In addition, there is talk of developing vaccines against malaria but in his lecture Bill Gates described the huge challenge of getting all vulnerable groups vaccinated. You have only to think of the less than complete vaccination coverage against measles in the UK to understand the scale of the problem.

So there may be no single ‘silver bullet’ solution to dengue fever and malaria. Perhaps the biggest impediment to solving this huge source of human misery is those who do not suffer from the problem trying to impose their views on those who do.

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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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