NIAB - National Institute of Agricultural Botany

Orson's Oracle

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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Precision application of nitrogen

Posted on 15/04/2016 by Jim Orson

A few months ago I attended a seminar at which all of the farmers present said that they had abandoned the precision application of nitrogen to wheat. This came as no surprise to me as I am unaware of a strong scientific base to support it. On the contrary, the scientific arguments against it keep strengthening.

One key issue is the way that wheat responds to nitrogen. It is possible to stray from the economic optimum by up to 50 Kg N/ha and have only a minor effect on both yield and margin. This is demonstrated by a slide shown to the HGCA (now AHDB cereals and oilseeds) conference a few years back.

Uncertainty in N rates

Therefore, based on nitrogen response data in individual trials, the economic optimum has to vary very significantly in a field before there are meaningful economic advantages for precision application of nitrogen, provided of course that the average dose is just about right. This overriding basic fact alone explains much of the disenchantment in the precision application of nitrogen to wheat.

Nitrogen trials are carried out in a small part of a field where the level of SMN may not vary much across the trial site. On a field scale SMN levels will vary more significantly and may provide an opportunity for precision application of nitrogen. This approach was tested in a major LINK funded project in the late 1990s. The test fields were divided into a grid and for each section of the grid a SMN measurement was taken and the estimated economic optimum was applied. The result was that the average yield of the grids was no higher than it would have been had the average dose been applied to the entire field.

This is perhaps explained by two factors. First, SMN is not a reliable indicator of soil nitrogen supply and second, SMN has far less influence on the optimum dose than previously supposed. A leading soil scientist told me a few years ago that SMN levels up to 100 Kg N/ha were “merely noise”.

Another possible reason to adopt precision application of nitrogen to wheat could be variations in potential yield across the field. However, yield does not influence the demand for nitrogen fertiliser by as much as suggested in some advisory systems. This is simply because high yielding crops use applied nitrogen and SMN more efficiently. If this is not so, how do you explain plot yields last year of 14 t/ha of wheat being achieved from 220 Kg N/ha in NIAB TAG trials carried out on-long term arable soils receiving no organic amendments? It did seem from these particular trials that additional nitrogen was necessary for plot yields above 14 t/ha.

Finally, there is an argument for spatially applying nitrogen according to the canopy size of wheat. Looking back at the graph at the beginning of this blog, this would typically bring small rewards in yield although it would help ‘even up’ the crop. The reward would be more significant in very variable oil seed rape crops where there is a good relationship between canopy size in the very early spring and the optimum economic dose of applied nitrogen.

You have to understand that the examples I have quoted above for wheat are for feed wheat and I have ignored the critically important issue of the environmental impact of nitrogen. It may be that there is a stronger argument for precision application to milling wheat. However, the understanding of nitrogen nutrition is still relatively rudimentary.

To make progress there needs to be further research at the more basic level. The trouble is that funders are more drawn to projects that offer quick fixes. As far as I can see there are no quick fixes in nitrogen nutrition that will provide the basis for precision application of nitrogen. However, there are those enthusiasts who continue to try to develop a system of precision application of nitrogen that will reap real rewards. I genuinely wish them well whilst reminding them that accurately predicting nitrogen doses for feed wheat to within a few Kg N/ha using the current relatively simplistic recommendation systems is at the moment not possible. The only potential case I can foresee for precision application of nitrogen to feed wheat is perhaps where there are very extreme soil types within a field and/or if there was a way of predicting variations in the efficiency of soil and applied nitrogen use across a field.

Remember, the first rule of precision farming is to assess how much variation there is and then assess whether or not there is an economic advantage in spatially varying an operation in order to correct or minimise it. Good basic and applied science, correctly interpreted, has a significant role to play here.

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Beware of correlations!

Posted on 01/04/2016 by Jim Orson

March is the month of the Cambridge Science Festival and I attended a few lectures. The programme was less plant-orientated this year and one of the major themes was big data.

The lecture I attended on big data and medical science was superb. The lecturer was brilliantly modest, ensuring that his points were understood by the wide-spectrum of knowledge in the audience. Put it this way, even I understood it!

First of all, he undermined some of the bunkum that goes with the term big data. As he said, it is data analysis. The issue is that so much data is now being generated in the medical world that it is becoming ever more challenging to analyse it and extract meaningful messages.

He warned that correlations in data do not mean causation. The well known example he quoted was the close link between ice cream sales and shark attacks in Australia. This is simply explained by the fact that there are more people in the sea on the hot days when ice cream sales are high. Hence, stopping ice cream sales will not prevent shark attacks.

Another example I can remember was when someone found a correlation between the fall in sparrow numbers in the UK and the rise in lead-free petrol sales. This amazingly lead to suggestions that there should be an investigation into the environmental impact of the additives in lead-free petrol but that proposal soon ran out of gas (pun intended).

In the medical world, there is a real danger of correlations leading to false conclusions that may impact on the lives of many people and so much of the lecture was based on this issue. There are some similarities in arable agriculture.

During the 1970s it was fashionable to say that high wheat yields were correlated with crops that had a high above-ground biomass at harvest. When you think about it, it is stating the b******* obvious. At harvest much of the biomass is in the grain and the rest is in the remaining above ground plant matter, notably straw. The two are related. Varieties tend to have a consistent harvest index, which is the proportion of total above-ground dry matter that is in the grain. Hence, inevitably high yields must be associated with high levels of biomass.

The correlation between wheat grain yield and high biomass crops was the basis of the Schleswig-Holstein system. This attempted to have a high biomass throughout the life of the crop, starting with high seed-rates and continuing with encouraging high growth rates from early spring onwards. Also in the 1970s there was another approach called the Laloux system. This stemmed from research by the then Professor of Agronomy at the University of Gembloux in Belgium. This was based on modest seed rates (roughly what we use now) and a more measured programme of feeding and protecting the crop in the spring and early summer. I did trials comparing the two approaches and the Laloux system consistently outyielded the Schleswig-Holstein system. The striking observation of the trials was that by harvest the two systems gave similar looking crops. Obviously the weather intervened and influenced final tiller numbers and biomass.

In the event, the then best UK practice was equal to or superior to the Laloux system. This was partly due to the fact that the Laloux system relied on late nitrogen applications. These are relevant to Belgium because of the regular incidence of thunderstorms in late May and June but not to the UK where it may be as dry as toast at that time of year.

Hence, whilst there is an obvious correlation between wheat biomass at harvest and wheat yield, it may not necessarily be pointing a way towards growing higher yielding crops. Obviously, things would be different if there was a correlation between yield and wheat biomass at a far earlier growth stage.

Last year proved that good standard UK practice can result in very high levels of biomass and yields provided that the weather is with us. Therefore, the approach must surely be to ensure that crops are able to take advantage of such conditions in order to achieve high levels of biomass at harvest without spending a shed load of money.

By the way, Gembloux is a very small town. I have visited the superb Department of Agronomy of the Agricultural University a few times and on occasions my wife came along too. The first time I suggested she looked around the town and we would meet up for lunch. I think it took her less than an hour to ‘do’ the town but the salads in the restaurant at the gates of the University made up for that.

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Preventing broad-leaved weed resistance is a priority

Posted on 17/03/2016 by Jim Orson

The EU referendum debate is getting quite emotive. It is almost a carbon copy of the Scottish independence debate. There are those who support an improving status quo who are saying it would be a mistake to rock the boat and there are those who say that real progress will only be made if we are independent. The problem is that really no one knows what the future will hold and so the argument is between ‘project fear’ and ‘project faith’. It is sometimes easier for the ‘project faith’ lobby to be positive, an example being SNP’s assertion in the debate on Scottish independence that Scotland would reap huge rewards from North Sea oil. However, events conspired to show that this forecast was a little hollow.

In one or two aspects at least, the future of pesticides looks a little more certain. Resistance and registration issues will continue to increase. However, the full implications of both are not certain.

Unlike with fungicide and insecticide resistance, individual farmers can largely dictate the future of herbicide resistance on their own farms. Hence, they need to think about this issue with great care and, as I have said before, adopt a change in mindset. No longer should a low level infestation of weeds showing above a crop go un-rogued. This applies mainly to grass weeds but broad-leaved weeds such as charlock should also be removed if at all possible. In other countries there is herbicide resistance in charlock and its near relatives and it poses a huge problem in parts of Australia.

There is also a need to exploit the weaknesses of already resistant weeds. I was reminded of this the other day when I received an email from a Western Australian farmer who had read one of my recent blogs on managing black-grass between crops. He described a machine that crushes the seed of their extremely herbicide resistant rye-grass (Lolium rigidum) as it comes over the back of the combine. This approach has the ability to kill 50% of the viable seed that has been set in the harvested crop.

black-grassUnfortunately, black-grass seed is shed before harvest but it has other weaknesses which can be exploited. I will not go over, yet again, the cultural measures that can be used to reduce populations except to say that its major weaknesses are that it cannot emerge from depths greater than 5 cm and that it is very much an autumn germinator. Rye-grass (Lolium multiflorum) is also autumn germinating and vulnerable to burial below 5 cm.

Wild-oats (Avena fatua) has fewer weak spots that can be exposed by changes in cultivation and time of sowing. It is both autumn and spring germinating and can emerge from greater depths, perhaps up to 15 cm. Its greatest weakness is that it shows above crops and hence is vulnerable to hand-roguing. There are a handful of populations that now show quite frightening levels of herbicide resistance and I am sure that it is advisable to reduce all populations to levels where they can be rogued if necessary.

The other forms of herbicide resistance in UK arable crops are common poppy, common chickweed and scentless maywPoppieseed resistance to the ALS mode of action of the sulfonylureas and one or two other herbicides. In Spain, poppies have developed resistance to a range of modes of action. I have been trying to think of the weaknesses in their growth cycle that can be exploited by cultural control measures. Unfortunately, I cannot think of any other than either killing the crop, adopting grass leys in the rotation or mechanical weed control.

Hence, although herbicide resistant annual grass weeds get the headlines, it is the herbicide resistant broad-leaved weeds that could eventually have the greatest impact on our arable systems. So please ensure that there is a herbicide resistance strategy adopted on each arable farm, which generally means rotating herbicide modes of action. There is a temptation to use more sulfonylureas for broad-leaved control as more spring barley and wheat is grown on farms that have herbicide resistant black-grass. This should be tempered by a sound anti-resistance policy, partly because the future of some alternative modes of action is uncertain.

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Silencing scientists?

Posted on 04/03/2016 by Jim Orson

In the last couple of weeks I have been viewing the lights of Cambridge from the top of the Gog Magog hills (well they pass for hills in Cambridgeshire). To explain, I drive over the hills whilst returning home from my golf club.

There are now two levels or layers of lights. The lower layer comprises the normal lights of a city: houses, flats, streetlights etc. The upper layer comprises red lights that mark the top of the large cranes on the many construction sites in and around the City. I do not know how many cranes there are but the effect of their lights at night is quite striking. Some have likened the skyline to that of Dubai during its rapid expansion.

I have often wondered what it must be like to operate such cranes. However, I will never find out because I am a wimp when it comes to heights. The overviews of the City must be great but of course to see the precise detail of a specific location you have to be at ground level.

I am becoming increasingly concerned that the views of those who work at the ground level of science and who know the nuances and details of the subject are becoming more and more pushed aside by those who have just an overview of the issues. This is a worrying trend and one which shows signs of getting worse.

Last year there was a missive from the Cabinet Office demanding that all civil servants (many scientists are civil servants) must seek prior permission from a minister to speak to the media. This feels like a restraint on scientists engaging pro-actively with topical controversies such as badger culling and gene editing. I realise that ministers have scientific commitbadgertees in order to inform decisions but there are, inevitably, many expert scientists who are excluded from this process.

There is now further concern that UK scientists may be prevented from arguing for changes in national legislation or policy if research grants are not exempted from a government ban on the use of public funds for political lobbying. This ban was announced in February and will be introduced in May. This prohibition could impact on University and Research Station staff who are receiving support from public funds. Much agricultural research is publically funded by the BBSRC (Biotechnology and Biological Sciences Research Council). Does this mean that these scientists will not be able to take part in public debates on scientific issues relating to policy or to respond to public consultations in their areas of expertise?

At the moment there is confusion on this issue and the government department responsible seems unable to provide clarification. This has prompted a petition which many scientists are signing. I sincerely hope that it is not the government’s intention to gag scientific opinion and that clarification will protect the right of scientists to make their informed opinions widely known.

Without such clarification life for scientists will become very difficult because ‘lobbying’ is not easily defined. Nor is it easy to define a policy issue. For example, some scientists have commented that a recent paper stating that ‘organic’ milk is more nutritious for consumers is flawed. The paper compares ‘organic’ milk from grass-fed cows with ‘conventional’ milk. The flaw is that the comparison should have been between ‘conventional’ milk from grass-fed cows and ‘organic’ milk from grass-fed cows. It has been known for some time that grass-fed cows produce more nutritious milk: even I knew this!

The criticism of this paper is perhaps just scientific opinion rather than lobbying. However, organic production could be seen by some as part of government policy. Hence, the uncertainties of the boundaries between scientific opinion and lobbying would inevitably inhibit scientific comment and progress should the lobbying by scientists receiving public funds be banned. Let’s hope further clarification from government will prove that this concern is a storm in a teacup.

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