NIAB - National Institute of Agricultural Botany

Orson's Oracle

Black-grass votes to remain

Posted on 24/06/2016 by Jim Orson

We may have voted to leave the EU but black-grass has decided to remain. It is hard to generalise but for many, particularly those who have yet to grasp fully the enormity of the problem, there has been a backward step this year in its control in winter wheat. Some farmers still have a rather touching faith in what herbicides can achieve.

In many situations the pre-em/early post-em herbicides gave good control of black-grass plants in the autumn. However, the survivors grew strongly in the warm autumn/winter conditions and established more black-grasstillers than perhaps could reasonably be expected. In addition, in some areas wet soil conditions meant that crop competition was disappointing, particularly in the poorer drained parts of fields.

There are instances where just a couple of weeks delay in drilling has had a remarkable effect on black-grass populations. The critical period in many areas was when drilling had been delayed from the beginning of October to mid-October. Soils were moist and obviously there was a high emergence of black-grass during that period. Crops drilled in the middle of the month rapidly established and provided good crop competition. The later drilling would also have helped the efficacy of the herbicides.

Conditions for the spring establishment of cereals were not as favourable as in the previous four years, particularly on the really heavy soils. This resulted in later drilling dates, which may theoretically have been advantageous in terms of black-grass control. Despite the later drilling dates, there was often sufficient moisture for the soil residual grass weed herbicides. Hence, herbicide use in spring barley provided good reductions in black-grass numbers where there was good crop competition. The issue in spring wheat was the restricted herbicide options for black-grass control. This, I hope, will be rectified in the coming seasons.

Personally, I am not in favour of delaying spring drilling of cereals in order to take full advantage of black-grass emergence prior to drilling. In my opinion, it is far better to drill as soon as conditions allow in order to maximise the possibility of soils being moist for the residual herbicides and to help ensure that the spring cereal is competitive. In addition, residuals are more likely to be ‘hot’ in the warmer conditions that tend to prevail later in the spring.

For the first time in three years I am not aware of any instances of exceptional numbers of black-grass emerging in spring drilled crops. It tends to confirm my suspicion that this phenomenon was due to the cold and wet summer of 2012 resulting in ‘super-dormant’ seed being set. It seems that it has taken three seasons to clear the back-log. In parts of Eastern England the last few weeks have been cold and wet. Hopefully it will turn warmer in the near future to ensure that we do not go through the same experience again.

So what has another season’s experience taught us? I think it has confirmed that many farmers and advisers need to assess more carefully the threat of black-grass to next year’s autumn sown crops. There is no point in taking an unrealistic view of what herbicides can achieve. In many instances the background population of black-grass needs to be reduced to a level where herbicides can prevent yield loss and also provide the best chance of limiting seed returning to the soil. This means that there should be the potential of no more than 10 black-grass plants/m2 (at a push 15/m2) emerging in an untreated winter cereal crop. Such numbers do not occur in an autumn sown cereal where there is so much black-grass emergence between the previous and the current crop that at least two applications of glyphosate are required in order to prevent emerged black-grass plants reducing further emergence through competition (no, it is not allelopathy). In such situations, winter or spring drilling are the only options.

All farmers and advisers are aware of the cultural options available and attention to detail is essential, such as estimating where in the soil profile the majority of the viable black-grass seed lies. This should help to guide the choice of type and depth of cultivation required. All approaches should be considered, including hand and chemical roguing.

I constantly witness the value of the strategic use of the plough. Now, please do not get back to me and say that ploughing would ruin the soil after many years of adoption of non-plough tillage. I have never seen any trials or field evidence to support such a statement. All options have to be considered!

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World hunger continues to fall

Posted on 10/06/2016 by Jim Orson

I cannot remember the exact year when I spoke at a large conference on the possible introduction of GM crops into the UK. It was perhaps the final year or two of the last century. After contacting a few aid charities I felt able to say with confidence that the number of undernourished people in the world was falling. However, I mentioned my concern that in Northern Europe we had almost exhausted the potentials of pesticides and crop nutrition. This was the main premise of my support for GM crops.

The statement that the number of undernourished people in the world was falling seemed to enrage the green groups present. I still do not know exactly why but shortly after my talk they posted reports on the web saying that I was wrong. However, as usual, they produced no evidence. I can only assume that they wanted to present conventional farming as failing to feed the world.

There is now a great database on the web that allows me, as well as the green blob, to obtain a more precise guide. This database is faostat3 produced by the Food and Agriculture Organization of the United Nations. All the data in this blog is as presented in faostat3.

This confirms that the number of undernourished people in the world was indeed falling at the time of my talk (see the first figure). The period covered in this figure (1991-2015) was a time of rapid expansion of the world population which meant that the proportion of undernourished people was falling more rapidly than the absolute numbers indicate. Unfortunately, the numbers rose in the early years of this century before falling significantly over the last ten years or so.

What is more heartening is the fact that the world food supply, in terms of Kcalories per person per day, is still rising significantly (second figure).

The third figure shows (in millions of tonnes) that the world wheat production continues to rise. The area of wheat grown in the world has remained roughly the same since 1975 and so the increase in production comes from improved yields (the fourth figure with yields quoted in one tenths of a tonne/ha). Over all, this is good news for the environment because the greatest environmental damage results from destroying wild vegetation in order to provide arable land.

In fact, since 1975, the annual average growth rate of the area of wheat in the world has been slightly negative whilst production and yield has increased by between one and two percent per annum (fifth figure).

The sobering fact is that much of the continued rise in wheat production has come from Asia, which accounts for about 45% of the world’s wheat production. China and India are easily the world’s top two wheat producers. Reassuringly, Africa is increasing production, in percentage terms, at a faster rate than any of the major continents (sixth figure).

With such increases in wheat production, was I too parochial when I made the argument that we needed GM to help feed the world’s future population? I believe not. Remember that GM crops were introduced in the US in 1996 and that there are currently around 180 million hectares of these crops grown annually in the world (around 14% of the world’s area used for the production of primary crops). The green blob has downplayed this amazing rate of adoption, saying that it is a failed technology. They are obviously using the same approach as in the late 1990s when they challenged conventional agriculture’s ability to reduce world hunger.

GM crops have contributed to some increases in yield, but not in wheat, but there is a lot more to come from both it and the more recently introduced biotech-based developments. We need these developments because pesticide resistance and availability are challenging our ability to maintain production at current levels. However, will we ever see the widespread introduction of GM and other biotech-based products in Europe? That is not easy to answer but significantly, the green blob are having increasing problems with the press who have realised that such approaches, properly regulated, can be a force for good.

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Where does all the nitrogen go?

Posted on 27/05/2016 by Jim Orson

I have tried cover crops on my allotment over the last year. They looked great in mid-October (see pictures), with the late-summer sown phacelia and vetch growing to an enormous size before being killed by the mild frosts of this last winter. Early-autumn sown spring oats also grew rapidly to a huge size but the winter only killed about half the plants.

The following spring-sown vegetable crops are now growing well where I dug the ground before sowing the cover crops but not where I have not dug or deep cultivated the soil for a year or two. So I have reluctantly decided that digging is still currently required before sowing or after removing the cover crops. I have also decided that the only cover crop that I will continue to grow is spring oats. The seed is cheap (well free!), establishment is more reliable and the soil is in good shape afterwards. In addition, there are no disease implications for the vegetable crops I grow.

Over the spring I have witnessed a few large scale on-farm experiences with autumn-sown cover crops. Their impact seems to have been favourable where the soil has been light enough to carry out sufficient cultivation prior to establishing spring-sown crops. A few half-field observations suggest a more vigourous spring-sown crop after cover crops. However, there is an active debate about the economic benefits of cover cropping, particularly on the heavier soils.

One intriguing aspect of autumn-sown cover crops is that they significantly reduce over-winter nitrate leaching but UK trials suggest that there is no opportunity to reduce nitrogen application to the following spring-sown crop. So what is going on? What happens to the nitrogen that has been prevented from leaching to the lower layers of the soil or to the drains?

There is a cover crop experiment in France investigating the impact of a late summer/early autumn-sown white mustard cover crop in a winter wheat, spring barley, spring pea rotation. A paper written after the first 12 years of the experiment confirms that the reduced nitrate leaching over winter does not reduce the economic optimum nitrogen dose for cereal crops. The measurements taken show that much of the nitrogen saved from leaching goes into storage in the soil organic matter.

Modelling based on the results of this and two other long-term cover crop trials in France suggest that over time, the benefit of cover crops reducing nitrate leaching decreases. However, it concludes that after twenty years or more, the economic optimum dose of nitrogen for crops can be reduced by around 20-24 kg N/ha and that this reduced dose restores much of the benefit of reduced nitrate leaching with autumn-sown cover crops.

It is worth pointing out that these long-term experiments all have non-leguminous cover crops. The nitrogen implications will no doubt be different where leguminous cover crops are adopted.

In the UK winter cropping may well have similar nitrogen dynamics to spring cropping plus autumn-sown cover crops. Hence, interpreting this French research in terms of practical implications for the UK is, to say the least, difficult. However, I am relieved that the modelling work provides the possible long-term implications for the nitrogen that is prevented from leaching over the winter by the introduction of autumn-sown cover crops and also the possible impact on nitrogen fertiliser requirements.


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Is glyphosate David or Goliath?

Posted on 13/05/2016 by Jim Orson

I must admit to getting emotional when Tottenham failed to get the points to challenge Leicester City for the Premier League title. Much has been written about the significance of Leicester’s win and, for me, it has added spice because Leicester and Tottenham have history. Leicester lost to them in the 1961 FA Cup Final and also lost out to them for the League title in 1963.

I am amused by the fact that the odds of a Leicester win were 5,000:1. This is quoted time and time again as if these odds are real. In fact they are just numbers adopted by the bookmakers. Apparently the odds are only 2,000:1 on finding Elvis Presley alive and kicking; well perhaps not kicking too vigorously as he was born in 1935. However you present it, the press and the public see Leicester’s League title as a triumph for the underdog and a real David v Goliath story.

This has got me thinking about the current travails of glyphosate, the biggest selling pesticide in the world. It is for this reason and its association with GM that it has become a target of the green blob. Now they seem to be having some success in making registration authorities think through the extra ‘evidence’ they have presented against it. I have put ‘evidence’ in inverts because of the standards and relevance of some of the ‘science’ being used to question glyphosate’s safety.

The green blob’s breakthrough came when the International Agency for Research on Cancer (IARC, which is part of the World Health Organisation) listed glyphosate as probably carcinogenic to humans. I wrote two blogs on this subject questioning their decision-making: Glyphosate cancer confusion and Roundup causing cancer? The second of these blogs was written after the European Food Standards Agency questioned the IARC decision.

It may be that the IARC decision was heavily influenced by the presence of a member of the green blob on the inside who helped to lead the decision-making process. This is a quote from an article by Matt Ridley in The Times on 23rd April:

Yet the document depends heavily on the work of an activist employed by a pressure group called the Environmental Defense Fund: Christopher Portier, whose conflict of interest the IARC twice omitted to disclose. Portier chaired the committee that proposed a study on glyphosate and then served as technical adviser to the IARC’s glyphosate report team, even though he is not a toxicologist. He has since been campaigning against glyphosate.

The IARC study is surely pseudoscience. It relies on a tiny number of cherry-picked studies, and even these don’t support its conclusion. The evidence that it causes cancer in humans is especially tenuous, based on three epidemiological studies with confounding factors and small sample sizes “linking” it to Non-Hodgkin lymphoma (NHL). The study ignored the US Agricultural Health Study, which has been tracking some 89,000 farmers and their spouses for 23 years.

The study found “no association between glyphosate exposure and all cancer incidence or most of the specific cancer subtypes we evaluated, including NHL . . .”

The worrying implication is that far-reaching and important decisions made by major international bodies can now be unduly influenced by the green blob. Surely this cannot continue and there has to be a return to objective and independent decision-making.

The pressure on glyphosate continues. A recent article in The Ecologist suggests that glyphosate kills a key soil fungus. However, it seems that the soil fungus used in this study was artificially exposed in the laboratory to concentrations of formulated glyphosate at levels that would not be found in the field soil environment. Previous investigations using standardised tests show that glyphosate formulations have no long-term effects on microorganisms in soil. I now never read The Ecologist after its leader once suggested that the world should eschew conventional and organic agriculture and we should all go back to hunting and gathering. Need I say more?

So is glyphosate David or Goliath in the fight for its future? I suggest that it is David because of the mass ranks mustered by the green blob that regularly use arguments not based on realistic science. It is as well to remember that everyone loves the underdog; just take Leicester City as an example.

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What is conservation?

Posted on 29/04/2016 by Jim Orson

Recently, the David Attenborough Building opened in the centre of Cambridge. It provides office accommodation for 500 (yes five hundred) conservationists. These are university researchers, post-graduate researchers and representatives of both UK and international organisations. Hence, it is a boiling pot of ideas but it seems that there is one thing that they cannot really settle upon: that is a universally agreed definition of conservation.

One definition has been suggested in a recent paper; ‘actions that are intended to establish, improve or maintain good relations with nature’. I do not think that anyone can disagree with this very broad-brush definition: a more precise one seems harder to agree.

A few weeks ago I attended a seminar entitled “what is conservation?” at the David Attenborough Building. Incidentally, the building was so recently completed that the PA system did not work and there were some wires hanging down from the ceiling. I assumed that a full Health and Safety assessment had been carried out!

One speaker’s approach was to accept that conservation means halting or interfering with natural succession otherwise all the ‘unmanaged’ land would eventually end up as deciduous woodland. However, with the example she gave, I felt a tiny bit uneasy about her approach. She described a deciduous wood on the North Norfolk coast that had grown on some boggy land. In the mind of the conservation agencies it would be better for general biodiversity to return the wood to a boggy area with few trees. However, the local villagers rather enjoyed their wood but they were persuaded that chopping down the trees would increase the conservation value of the site. The speaker says that the villagers now enjoy the wildlife in the recently cleared area but I think it has taken an enormous effort to reach this end point.

Of course there would be little natural succession to halt if it was not for farmers originally clearing land to produce food. It is the broad spectrum of habitats in the natural succession between intensively cultivated land and deciduous woodland that provides the home and food for the huge range of plants, insects and animals that form the biodiversity of this country. Hence, there is a real need to manage uncropped land to support biodiversity.

A recently published paper attempts to attribute the cause of the changes in biodiversity in the UK since 1970 and concludes that agricultural management and climate change are the major drivers. It suggests that we should adopt lower intensity farming to help reverse some of the negative trends in biodiversity measured over this time period. Of course, the overriding issue is that the world population has doubled since 1970 and demand for food will continue to grow.

What I have not been able to glean from the scientific literature is the cost to biodiversity of producing say one tonne of wheat from different approaches to arable production; organic, low-intensity and conventional. There are such studies for greenhouse gas production. They conclude that despite the greenhouse gas production associated with the production and use of nitrogen fertiliser, there is a lower amount of emissions when producing a tonne of wheat conventionally rather than organically. I suppose that biodiversity is too multi-faceted to try to do the same analysis for it.

There has been an attempt to compare the value to butterflies of conventionally and organically managed land. This concludes that ‘farming conventionally and sparing land as nature reserves is better for butterflies when the organic yield per hectare falls below 87% of conventional yield. However, if the spared land is simply extra field margins, organic farming is optimal whenever organic yields are over 35% of conventional yields’.

This suggests that conventional farmers have to manage their uncropped land better. I think that this is supported by the paper I previously quoted on the cause of changes in biodiversity since 1970, which suggests that the way the habitat is managed has a greater impact than changes in its extent. I assume that the authors are suggesting that this applies not only to cropped land but also uncropped land.

This all suggests that in order to relieve the intense pressure to increase the biodiversity of arable land, the first step the industry needs to make is a significant improvement in the management of uncropped land.

P S – Despite the fact that they had a brand new building for 500 conservationists in the centre of Cambridge, the speakers at the seminar did appear to agree on one thing; ‘not enough funding’.


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