NIAB - National Institute of Agricultural Botany

Orson's Oracle

English wheat harvest 2016

Posted on 08/07/2016 by Jim Orson

I have just attended the funeral of a former colleague. One reading included the following words: “There is no longer any room for pretence. At harvest time the essence is revealed – the straw and chaff are set aside, they have done their job. The grain alone matters – sacks of pure gold.” Sacks of pure gold may be an exaggeration with today’s market prices.

What will the English wheat harvest of 2016 reveal? Over the last few years I have written a blog in early July, half way through grain fill, trying to predict yields. As usual, I have not really got sufficient meteorological data to attempt a complete scientific analysis. Nevertheless, here goes.

wheat harvestThere have been studies to try to associate historical wheat yields with weather conditions. The most notable was published in 2000. This states that the most influential weather impacts on the yields of well grown wheat crops are (1) negative effects of rainfall before and during anthesis (early June), during grain-filling and in the spring (2) winter frost damage (3) a positive effect of the temperature-driven duration of grain-filling and (4) a positive effect of radiation around anthesis, probably due to increased photosynthesis.

Naturally, there may be an interaction between rainfall and solar radiation. Radiation levels are low in wet weather. This might help to explain some of the dominance of rainfall distribution in this analysis.

The importance of lack of rainfall at key times is highlighted. “Negative effects of rainfall during the estimated early-reproductive phase, the estimated anthesis phase, the estimated grain-filling phase and the February/March period are the most dominant effects in the climate response sub-model (explaining 54% of the grain yield variation accounted for by the model).”

This strikes a chord with my experience. High wheat yields seem to be associated with dry but not drought years e.g. 1984, 2014, 2015. May rainfall explained much of the yield variation throughout the country last year. Where there was little rain in May, drought conditions limited the potentially very high yields.

In 2014 and 2015, we had dry conditions from mid-February/March, April and June, the stages highlighted by this paper. In addition, we had a long grain fill because of coolish conditions both day and night (Number 3 in the paper summary above) and good levels of radiation around anthesis (Number 4 in the paper summary above).

For much of the country, this year’s weather does not appear to point to high yields in 2016. February had average or lower than average rainfall and March was dry in the North East but the rest of England had a wetter March than average. We had plenty of rain in June in much of the country but again the North East had average rainfall. Radiation levels were generally around average for much of the spring but, critically, lower than average in June, except in the North of England, which enjoyed average or above average sunshine and radiation. June temperatures were higher than average except close to the East Coast where the cold North Sea temperatures resulted in average temperatures in the coastal strip from North Norfolk northwards.

Therefore wheat yields are likely to be around average, perhaps on the disappointing side of average in the central and southern areas that have had particularly low levels of radiation and well above average rainfall for June. The exception might be the very North of England where I suspect that there will be above average yields but perhaps not at the levels achieved last year, providing, of course, that the harvest weather is good.

The paper I quoted earlier in this blog probably reinforces rather than forms my somewhat instinctive conclusions. As usual, I hope yields will be better than I predict!

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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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