NIAB - National Institute of Agricultural Botany

Orson's Oracle

Wheat yields – not just a great summer

Posted on 16/10/2015 by Jim Orson

My blog in early July suggested that yields might be good except in those parts of the country where a very dry May/June could limit the yield potential on all but the most moisture retentive soils. This was along the right lines and yields have been exceptionally high in some areas but the dry conditions in May/June perhaps did not limit yields as much as I thought they would.

So I have revisited some of the weather data I reviewed for the July blog in order to try to explain the exceptionally high yields experienced by some growers. Unfortunately, I am still pursuing solar radiation data that is hard to come by and will continue with my quest. In the meantime I thought I would set out my preliminary thoughts in this blog.

The solar radiation data that I have, and which does not cover some of the extremely high yielding areas, suggest that it was well above average for the whole growing season. However, it was not exceptionally high during grain fill.

Overall, temperatures from January to July were very close to average for the arable areas of England. In the July blog I noted that the cool nights in June could be beneficial only because the crop would not respire overnight so much of the gains made during the day. These cooler than average overnight temperatures were a particular feature in North Yorkshire and Northumberland where some of the highest yields occurred. These areas also had good levels of rainfall in May/June.

What may also have been very significant in determining yields this year was the higher than average amounts of solar radiation in March, April and May. The amounts in April were exceptionally high. This may have resulted in higher than average levels of tiller growth and survival, grain sites/ear and stem reserves. Hence, it may be reasonable to suggest that the higher yield potential established in the spring was realised by much better than average, but not exceptional, conditions during grain fill. It is interesting to note that a recent AHDB (the old HGCA) Project Report 496 suggests that modern wheat varieties have higher levels of stem reserves than those introduced over a decade or two ago.

My July blog suggested that overall yields would be higher north of the Wash because of rainfall patterns and the fact that temperatures on the 1st July were not as exceptionally high as those which occurred further south. We will never know the impact, if any, of that very hot day on final yields.

So it seems that there was no one standout feature that resulted in the very high yields this year. On the other hand, the weather throughout the year favoured high yields. The crops wintered well, with little or no waterlogging, and experienced very favourable weather in the spring and summer, except in those areas which suffered from drought stress during May/June.

There will be another blog on this issue when I have more data on the structure of some of the very high yielding crops and on the weather, particularly solar radiation.

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The value of a day’s delay

Posted on 02/10/2015 by Jim Orson

We got up at 2:30 a.m. the other day to view the eclipse of the super moon. The fact that we had a good view of the event meant that the sky was clear. The weather was set fair and so I knew that cereal drilling would soon be going ahead at a frantic pace.

Do not take this wrongly but I was hoping for another few days of delay in drilling winter wheat. Wet weather delayed drilling until about 10th October in 2009 and ensured high levels of black-grass emergence prior to that date. This was also the first autumn of the wider adoption of stacking of the pre-emergence herbicides. The resulting black-grass control was generally more than satisfactory. The level of control was attributed by many to the stacking of the pre-emergence herbicides but the involuntary adoption of the cultural control measure of delayed drilling also played a significant role.

After a wet spell there is always the temptation to get on the land and drill before it is really suitable. The most extreme case was in the autumn of 2000 when it seemed to rain almost every day. Surveys of NIAB TAG members clearly showed that those who puddled-in wheat that autumn had inferior yields to those who waited for the better soil conditions in the first couple of months of 2001.

What has always amazed me is the rate of reduction in soil moisture below a depth of 30cm. One day the spade would tell me it was too wet to cultivate but the next day it seemed dry enough to cultivate. Salle Farms in Norfolk, which keeps meticulous records, have shown that for a few days yields increase with every day’s delay in drilling after a sodden soil starts to dry.

Now, there is data to demonstrate the impact of leaving the soil just another day (see the diagram) or preferably two days before wheeled or tracked vehicles run over it. This data was collected by the University of East Anglia as part of their government funded research project, the Demonstration Test Catchment study of the River Wensum in Norfolk. It shows the rapid drying of the medium textured soil at 30-50 cm depth between 5th February and 6th or 7th February 2013 despite little change in the moisture status of the shallower layers. As farm equipment has got heavier over the years this information takes on added significance in trying to avoid compaction in the deeper layers of the soil.

The take home message is quite obvious, do not rush back onto the land as it starts to dry after it was sodden. A day or two’s delay may be handsomely rewarded in terms of crop yield. Regular use of a spade will only confirm the message and improve decision making. So keep digging.


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Top shelf reading

Posted on 16/09/2015 by Jim Orson

Farmers Weekly has been moved to the top shelf at our local shop (Waitrose). I am not sure why. Is it because of some risqué language in the livestock section or the frequent mention of (oilseed) rape in the crops section? Or is it because the powers that be at Waitrose have read the popular book by Yuval Noah Harari entitled Sapiens: A Brief History of Humankind? Naturally, there is a reference to agriculture in the book. The Guardian (I am not a regular reader of the paper) review of the book includes the following paragraph:

It's a neat thought that "we did not domesticate wheat. It domesticated us." There was, Harari says, "a Faustian bargain between humans and grains" in which our species "cast off its intimate symbiosis with nature and sprinted towards greed and alienation". It was a bad bargain: "the agricultural revolution was history's biggest fraud". More often than not it brought a worse diet, longer hours of work, greater risk of starvation, crowded living conditions, greatly increased susceptibility to disease, new forms of insecurity and uglier forms of hierarchy. Harari thinks we may have been better off in the stone age, and he has powerful things to say about the wickedness of factory farming, concluding with one of his many superlatives: "modern industrial agriculture might well be the greatest crime in history".

I am not sure what Harari means by modern industrial farming but it would appear to include both organic and conventional farming. This is because both forms of arable farming typically include growing grain crops.

Nor is Harari alone in these thoughts. I recently went for a check up at the doctors and whilst waiting my turn, I picked up a copy of The Ecologist. The main article stated that we would all be better off if we returned to being hunters and gatherers. Amazingly my blood pressure was at a reasonable level when tested a few minutes later!

wheatI am not sure where to begin in commenting on these thoughts. Humans were not tempted by the devil to grow wheat. They grew wheat because it offered them a better way of life; being able to put down roots and have a more reliable diet. Long hours would also be spent hunting and gathering and I suspect the limited amount of food available ensured that there was no risk of an over-crowded planet! I am sure there must have been a greater risk of starvation and malnutrition in the Stone Age. Living off the land is a romantic notion but the reality is rather different.

An ever increasingly efficient agriculture has released an ever increasing proportion of the world’s population to escape from what is often the day to day drudgery of producing food. It has afforded authors the education and the time to write books decrying current food production methods.

There is a whole spectrum of opinions on agriculture in society. I note that the new shadow Defra secretary is a vegan. She believes that eating meat is harmful to people and the environment. In some ways it is and it is true that significantly more resources are required to produce a kg of meat than a kg of a vegetarian or vegan alternative. It is just possible that if all humankind gave up eating meat, organically grown crops could feed the world, although there would be increased concern over food security.

However, all these noble notions cannot override the reality of the will of the people. The last leader who tried to force a rural idyll on his country was Pol Pot and look what happened there.

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GM back in the news

Posted on 03/09/2015 by Jim Orson

It is a fair time since I had a rant about GM. I am not alone as the following quote from a recent opinion piece in The Times demonstrates:

‘The debate around genetically modified crops would almost certainly puzzle an alien. “I don’t get it,” he’d beep, arriving on his first tour of Earth. “You’ve found a way to boost crop yields and reduce your reliance on pesticides. Repeated, peer-reviewed scientific studies have shown there is no downside. It could be the answer to a pending crisis of global hunger, with no ill-effect. Yet it still makes lots of people very angry, and many governments avoid it in horror. Why?’

It is very easy to answer that question. There are too many organisations who have pinned their reputation and, in some cases, their finances on being against the technology. It has also become an ideological struggle against ‘multi-nationals’. Hence, the same old scares are repeated and new issues are exploited as being evidence against the technology. A prime example is the reducing numbers of the monarch butterfly in the US. These iconic butterflies migrate in the autumn from southern Canada and northern US to a specific area in central Mexico in huge and spectacular clouds.

Monarch butterflyThe monarch butterfly first entered the GM debate when it was found that they died when contained in chambers heavily laced with pollen from Bt maize modified to control corn-borers. This is no surprise; if you continually expose an insect to very high levels of something that is known to kill it, it will die. The key issue is in real life would the monarch butterfly be exposed to sufficient amounts of this pollen to affect its health? The judgement of the experts is that it would not.

Despite this, there have been recent headlines that GM Bt and glyphosate tolerant maize is responsible for the recorded decline in the Monarch butterfly. However, looking behind the headlines is a more nuanced explanation. Monarch butterflies feed exclusively on native milkweeds (Asclepias species) and cannot survive without them. Native milkweeds are perennials that flourish in semi-natural areas such as road sides, edges of fields and also in uncropped land. The plant declined by 58% in the plains states from 1999 to 2010. Monarch populations dropped by 81% in the same period.

It now seems that the major factor in the decline of milkweed is that more land is now cropped with maize in order to supply the ethanol plants. Nearly 4.5 million hectares have been taken out of the Conservation Reserve Programme, much of it going into maize. It has to be acknowledged that glyphosate tolerance enables a higher level of control of native milkweeds in maize but the shift into maize and out of something akin to set-aside has been a major factor. This is an unintentional consequence of promoting biofuels.

Another reason for the fall in the population of the Monarch butterfly may be illegal logging in Mexico where it overwinters on trees. The logging was almost halted at one stage but there are recent reports that it has recommenced.

Taking the populist decision to ban GM, as the Scottish Government has done, is an easy way out for European governments. They are really abdicating their responsibility to lead the debate rather than just blindly follow public prejudice that has been stoked up by misleading and misinterpreted information. It seems that getting a better balance between crop production and biodiversity is ever more challenging and it is my view that GM technology can play a role in improving the chances of getting it right.

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Extreme weather

Posted on 20/08/2015 by Jim Orson

There was some interesting weather in the UK in July. The 1st was the hottest July day on record and a temperature of only 10C was recorded in Powys on the 31st. However, the extreme event of note for me was the overnight thunderstorm on 16th/17th in Cambridge. Up to that point, I was desperate for rain in order to perk up our garden and allotment. We had had rain forecast several times but received tiny amounts, if any at all. As they say in Norfolk, “it never rains in a dry time”.

Unfortunately we were away when the thunderstorm occurred and so I did not experience it at firsthand. The first I knew of it was when I checked the online weather station in Cambridge the following morning (I was that desperate for rain!). It said that there had been a total of over 50mm of rain overnight. When we got back on the 18th, I cycled up to the allotment where my rain gauge had recorded 80mm of rain. Up to 90mm was recorded locally. It must have been an amazing storm to witness.

This got me thinking about the challenges from weather events to our crops and their management. The dull and wet summer of 2012 was one such seasonal extreme event. It took a large toll on wheat yields in some parts of England, particularly on the heavy clays. I also clearly recall the dry and hot summer of 1976 (it was actually very dry from June 1975 to September 1976). It is not just the extreme summer weather events that can impact on our wheat crop; the wet autumn and winter of 2000 reduced the yields achieved in 2001. However, despite what we sometimes consider to be extreme weather variations, UK wheat yields are amazingly consistent from year to year when compared to some other parts of the world.

One notable example of large variations in yield over the years is in parts of Australia. There is an area in Victoria, north of Bendigo, called the Mallee, which is perhaps close to being marginal for arable crop production. Harm van Rees, a leading Australian agronomist, recently sent me the following data on its growing-season rainfall (GSR) expressed as deviation from average (rather than ‘of average’ as stated on the y-axis). As you can see, there have been a very high number of dry seasons over the last 15 years or so and the ten year running mean (the red line) is still going down. In the very dry seasons, wheat yields can be alarmingly low (often below 1.0 t/ha) or zero and many farms are in financial crisis. There was a similar but shorter downward trend of the ten year running mean in the 1940s. The anxiety about the current trend is heightened because of the concern over the possible influence that climate change may have been having on the rainfall in recent years and may have in the future.

So what would you do in this situation? Not an easy question to answer. Australian researchers have developed sophisticated risk management tools for use in arable farming, many of which are now based on seasonal forecasts. For instance, these help to decide on how much nitrogen to use as applying any nitrogen in a very dry year can reduce wheat yields as well as unnecessarily increase costs. A preliminary analysis suggests these tools are beneficial when compared to adopting the same management each year. As one researcher points out “the [seasonal] forecasts are too good to ignore, but not good enough to completely rely on. Even though there are uncertainties, we do have more information than if we were guessing by chance.” However, what farmers and bank managers in the area featured in the rainfall graph really need is a reliable forecast of rainfall not just for the season but also for the next few years.

A recently published report called Extreme Weather and Resilience of the Global Food System warns that major “shocks” to global food production will be three times more likely within 25 years because of an increase in extreme weather brought about by global warming. So we will have to accept that there are going to be even more challenges in the future. Achieving more resilience in our production systems to extreme weather events will have to be given a higher priority. It does not help the UK industry that pesticide resistance and legislation are together impacting on the resilience of our arable systems. It is also regrettable to have to say that opposition to GM may well reduce our ability to respond to the challenges of the future. The report can be found on

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