NIAB - National Institute of Agricultural Botany

Orson's Oracle

Resilience – run for cover

Posted on 28/11/2012 by Jim Orson

The yield plateau project which I referred to last week has started a flurry of emails. I received one from a farmer who has mapped out the average yields of the individual HGCA Recommended List winter wheat trials carried out over the last ten years. This shows the large variation in the average trial yields achieved in recent years compared to earlier years that experienced more benign weather conditions.

There may be a number of explanations for this; for example a change in trial sites. However, it could also indicate that winter wheat has insufficient resilience to withstand the weather shocks of recent seasons. For instance, the feature of 2011 was the prolonged drought from the end of February to the end of May, and the feature of 2012 was lack of summer sunshine and waterlogging in May and June.

The question this poses is whether we can increase the resilience of our crops in a future that seems to promise more regularly occurring weather shocks. Much is bound up in the physiology of the crop. I’ve written before about breeders’ attempts to ensure that a higher proportion of solar radiation is transferred into crop growth. This may help if we have years with such low levels of sunshine as in 2012.

However, droughts and waterlogging suggest we also have to think of trying to increase the resilience of the soil to provide the best conditions possible for crop growth. In addition, improving the ease with which good quality seedbeds are prepared is particularly relevant in years where more spring crops have to be grown because of a wet autumn. So, much of the resilience we seek in yields will have to come from making soils more resilient.

The glib response from some pressure groups and governments is to increase the organic matter of the soil. This would make soils more workable in a wider range conditions and increase water holding capacity. Well I agree, but the challenge is how do we do it? There’s not the necessary amount of organic manures and amendments available to increase the organic matter of all our arable land.

I remember that there was a suggestion a few years ago that to receive the single payment arable farmers would have to grow short-term leys in their rotations in order to increase organic matter levels. This soon got dropped when it was realised that any additional organic matter resulting from a short-term ley was soon lost when the land was returned to arable cropping.

An earlier blog did mention the value of the regular return of crop residues to the soil. This increases soil fungal biomass which provides some of the advantages of higher organic levels; for instance, soil fungal biomass increases the stability of soil aggregates. This means that seedbeds are easier to prepare and that they’re far less vulnerable to capping. However, to maintain soil fungal biomass it needs an annual return of crop residues or organic material.

An approach to further increasing soil fungal biomass activity is to grow cover crops, particularly prior to spring crops. I realise that there is a lot of hassle with this but the potential rewards of doing so are likely to be greater if the weather is going to become more variable.

In my opinion, one of the most valuable results of an HGCA project carried out by The Arable Group and Rothamsted Research (HGCA Project Report No 414) a few years ago never got any real publicity. It measured the value of growing mustard in the fallow year of a wheat cropping sequence (I don’t want to call it a rotation for fear of upsetting someone). This showed that after four years (and so after two mustard crops rather than bare fallow) the wheat yield was increased by 1 t/ha and both soil fungal biomass and soil water holding capacity were higher than when no mustard crop was grown.

Similarly, NIAB National Agronomy Centre’s New Farming Systems Project at Morley (funded by The Morley Agricultural Foundation and the JC Mann Trust) is beginning to show the accumulated value of cover crops sown in the autumn before establishing spring crops. The results show that legume-based cover crops are of particular promise. Hence, the evidence is building that if we want ‘living’ and more resilient soils in the absence of regular applications of organic manures, then we have to have the right plants growing in them for the maximum time possible.

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Stagnant yields and stagnant politics

Posted on 20/11/2012 by Jim Orson

If you write a blog there is a huge amount of fodder in a recent report of a desk study on the contributory causes of the current ‘yield plateau’ in wheat and oilseed rape. Funded by Defra and AHDB HGCA it was carried out by my colleagues at NIAB TAG with the Scottish Rural University College (SRUC, formerly SAC) and the Department of Land Economy at the University of Cambridge. You can find the report here on the HGCA website.

I suppose the first question is have yields plateaued? The answer is clearly yes for wheat but over the last couple of years the trend for oilseed rape has been upwards. However, even for rape, the improvements in yield delivered by varieties over the past couple of decades have not been reflected in an equivalent increase in field yields. The report tries to identify reasons for this.

Naturally, it is impossible to say with absolute confidence why average yields have not increased at the rate of improvement delivered by varieties. However the report thoroughly reviews the possibilities and has come up with some well argued conclusions. It also contains, for me, some ‘I didn’t realise that’ statements.

One intriguing fact is that the rapid rise in average wheat yields in the late 1970s and early 1980s was accompanied by a rapid fall in the proportion of the crop grown as second or subsequent wheats. This would only have increased the rate of rise in average yields.

Another issue is that 20% of soil samples tested are below the target P index for arable cropping and 30% are below the target K index. Whilst there is no evidence that this has contributed to yield stagnation, it is a remarkably worrying statistic in these days of knowledge-driven agriculture. Perhaps of equal concern is that only 60% of OSR crops receive inorganic sulphur fertiliser. The report acknowledges that some OSR crops may be getting sulphur from organic manures but there must be a fair proportion of crops not receiving any sulphur at all.

What really intrigues me is that the yield gap between the top yielding farmers and the bottom yielding farmers is getting greater. Now that could mean that timeliness is not perhaps as good as it should be on some farms. If less than desirable timeliness is due to low labour and machinery availability then that may have been an acceptable risk when prices were very low but not now.

In fact, with the growing background of pesticide resistance and losses in pesticides due to legislation, the benefits of improved timeliness are likely to get even greater. Everything has just got to be closer to the optimal conditions to achieve effective crop protection in the future.

Naturally, I have to jump back to a pet theme in any discussion on stagnating yields. In the 1970s and 1980s, we exploited new technologies of plant breeding and crop protection to achieve the rapid rise in yields. These improvements in crop protection have ground to a halt and all we can try to do is to prevent a step backwards as a result of pesticide resistance and pesticide withdrawals. What is really wanted now is better technology. This will primarily be delivered through plant breeding and, I have to say it, perhaps genetic modification.

In the 1960s the United Nations Food and Agricultural Organisation (FAO) produced a report entitled ‘Six billion mouths to feed’. It expressed fears that the then world population of three billion would be six billion by the year 2000 and it wasn’t clear how they could all be fed. This created a supportive political background for new agricultural technology, including pesticides.

As a result there was no concern about world food supplies by the 1990s. It was only when the fear of potential world hunger had receded that those who opposed the means of increasing food production gained political traction. We now face the next challenge of an additional three billion mouths to feed with those same groups still holding a grip on political thought in some EU countries, but not perhaps in the UK. This may reflect the fact that UK consumers are now beginning to realise that the scare stories promulgated about GM are simply not true, but the EU is losing valuable time.

We will never be sure of the potential of GM until we start on a road where the first simple discoveries, such as herbicide resistance, are allowed to be used to help companies finance more advanced and hopefully higher yielding crops. Like all new technologies, there has to be a first step.

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Meeting the challenge

Posted on 12/11/2012 by Jim Orson

I gave a talk in Cornwall last week. It was the only the second time I have visited that county as part of my job and the subject of the talk was equally unusual for me; weed control in grassland.

A large part of my presentation was about keeping pesticides out of water. You may think that there are no such problems in a largely pastoral county. However, South West Water is picking up some pesticides in raw water at concentrations that exceed the Drinking Water Directive. They tend to be the usual culprits including mecoprop and metaldehyde. Also, some of the more specialist grassland herbicides are being detected in water during the summer. The latter is also true for East Anglia, despite the low proportion of land that is occupied by grass.

Pesticides in water are currently a huge issue for both the agricultural and water industries. The standards are demanding, particularly for drinking water. In areas where drinking water is not sourced, pesticides in water have to meet the Environmental Quality Standards needed to protect aquatic life. For many but not all pesticides these are generally laxer than the standard for drinking water.

Now maps are being produced showing where drinking water is sourced and the land that drains to it over a short space of time. These are being designated Drinking Water Protected Areas (DrWPAs). Where surface water DrWPAs are at risk upstream Safeguard Zones are also being delineated. There are also some groundwater drinking water abstractions at risk from pesticides, but these are fewer in number.Drinking Water

By doing a postcode search in the Environment Agency’s ‘what’s in your backyard’ website, farmers can see if they are in such a surface or groundwater area. Just click on the icon with the tap on it (on the last row of icons). Should they farm in a Drinking Water Protected Area or Safeguard Zone then they will be have to be particularly careful about keeping pesticides out of water. However, even with the best will in the world problems may still occur.

So what happens next? There is much debate about this with a report being prepared on what needs to be done should voluntary measures fail in any area. There are a lot of possible options including removing authorisation of those pesticides that regularly occur in water at above the drinking water standards. Authorisation could be removed, either just locally where there is a problem, or nationally.

At the other end of the range is the option for Water Companies to pay for alternative pesticide or cropping practices to avoid offending pesticides being used in the Drinking Water Protected Areas (and also possibly the Drinking Water Safeguard Zones). In some cases this could prove to be the cheaper option. For example, Wessex Water is paying some farmers in key areas to use ferrous phosphate slug pellets rather than metaldehyde.

One option that really isn’t available is to install more treatment facilities to remove pesticides from water. This option is not desirable under the Water Framework Directive since it asks Member States to reduce the level of treatment needed at drinking water plants (complicated isn’t it?!).

Hence the issue of pesticides in water has a long way to run. It is a fundamental part of the UK National Action Plan for Pesticides that is being prepared as a result of the Sustainable Use Directive. It is clear that at least some of those who farm in the Drinking Water Protected Areas (and possible those in the Drinking Water Safeguard Zones) will have some very significant challenges to face over the next few years. So it is worth all farmers having a look at the website to check if they are in these areas.

For those outside these areas, the issue of pesticides in water still demands high standards of pesticide use. As I said earlier, the Environmental Quality Standards are generally less demanding. Cypermethrin is an exception. The Drinking Water Standard is 0.1 parts per billion but the Environmental Quality Standard for cypermethrin is 0.1 parts per trillion. This will mean a fraught process when it is re-evaluated as part of the EU pesticide regulations.

Finally, it is worth pointing out that there may be other areas of land designated to protect waterbodies such as those used for recreation or which have particular wildlife habitats etc. Life does not get any easier!


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Blemishes are back

Posted on 29/10/2012 by Jim Orson

It came as a real shock when my wife informed me that the local corner store was selling blemished apples. Perhaps it’s worth mentioning that our local corner store is a Waitrose supermarket and apparently they’ve done it before under the banner of fruit for jam-making.Waitrose blemished apples

However, selling blemished apples is neither a long way from, nor a long time since, when pre-packed fruit had to be without blemish and even in size. In 2009, an EU ban on fresh produce that didn’t match standard shapes and sizes was lifted. Up to that point as much as 20% of farm produce was thrown away or fed to livestock because it didn’t comply. Now pre-packed fruit and vegetables of mixed sizes are commonly on offer.

This year’s late frosts really hammered apple production in Northern Europe and it’s no wonder that more limited supplies mean less wastage by selling fruit that’s blemished. This is all a response to the new reality of more limited food supplies. One way to tackle a shortage of food is to reduce needless waste.

Surveys show that UK consumers are increasingly aware that there is a concern over future food supplies. This is a real turn-around. It wasn’t that long ago that Defra appeared to hold the view that UK food production was not that important. At the time I attended a meeting of researchers on the subject of sustainable land management. There was a significant number in the audience who thought that the last thing that our land should be used for was the production of food because it was far too environmentally damaging. They seemed to have no consideration that food has to be produced somewhere and that it would also inevitably be more damaging to the natural environment of the producing country than letting nature take its course.

There are other issues regarding the threat of food shortages. I’ve just read an article on the pros and cons of trying to bolster EU protein crop production. Much of the enthusiasm for this is based on the fact that non-GM supplies of soya are very limited. There are also strategic and food security reasons for the EU being less reliant on imported soya. The article’s author had calculated that 1.4 hectares of peas would have to be grown in Northern Europe to replace each hectare of soya beans grown in Brazil. In fact wheat produces more crude protein per hectare than peas in much of Northern Europe but of course the concentration of the protein in the harvested product is around half that of peas.

When you consider that land is one of the most limiting resources for food production this fact is of enormous significance. It supports the concept of free world trade in agricultural production where individual farmers only grow what they produce the most efficiently. In the UK we ‘do’ wheat and oilseed rape and in terms of land-use it is best to leave it to others to ‘do’ protein crops such as soya.

However, this bland statement hides other realities, such as the need for break crops. On the other hand, it seems that protein crops in Northern Europe have a long way to go to be competitive with soya, even when taking into account transport costs.

Let’s hope that R&D can deliver protein crops in Europe that can compete with soya or alternatively improve the prospects for home-produced soya. Until that time, financially inducing EU farmers through CAP to grow more crops than they can produce competitively in world markets or that are required to sustain a rotation doesn’t make much sense in the context of getting the best out of the current arable land in the world. It can only increase the possibility of more of the world’s remaining wild areas coming under the plough.

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Not a lot of people know that

Posted on 22/10/2012 by Jim Orson

You can imagine Michael Caine saying ‘not a lot of people know that’ when you hear that more sunlight hits the surface of the earth in one hour than the entire human race uses in a whole year.

Solar panels can generate electricity from solar radiation but it is intermittent and difficult to store. Only plants, algae and some bacteria have the amazing ability to capture and store the sun’s rays as sugars using photosynthesis. Unfortunately, photosynthesis is quite an inefficient process. For instance, in wheat less than 1% of the intercepted solar radiation is converted into plant material over the life of the crop. This can creep up to just over 1% during the grain fill process.

There are three photosynthetic systems - C3, C4 and CAM. The main ones are C3 and C4 with wheat and rice using C3 photosynthesis and maize and sugar cane the C4 system. The C4 system is far more efficient in converting solar radiation than C3, particularly in warm climates; for example, sugar cane can be up to 7% efficient. This means that the C4 systems also tend to be more efficient users of nitrogen and water in terms of crop produced per unit of input.Leaf stomata

So research establishments are taking the first steps in trying to convert both wheat and rice from C3 to C4. There is no guarantee that they can achieve this goal or that the C4 system in these crops will provide the expected increases in productivity. However, it is a breeding goal that is well worth investigating.

One of the reasons for the recent plateau in wheat yields is that we have exhausted many of the technologies that produced the huge steps forward in the 1970s and 1980s. There is little doubt that plant breeding offers the major opportunity to provide the much needed yield improvements.

When you look back, the technologies that can now be used to improve crop performance through plant breeding are amazing. My A-level biology studies were totally disrupted by the teacher’s enthusiasm to discuss the early findings of Crick and Watson, shortly after each paper was published. Now plant researchers are in a good position to say what traits they would like to see in a plant and identify a method to achieve that end. No longer is plant breeding based on serendipity - in just crossing specific varieties and assessing the outcome by eye.

I may be doing pesticide discovery a disservice by saying that they still rely on serendipity by just testing a range of chemicals and seeing if they work. I realise that it has become more sophisticated over recent years with high throughput screening. However, I have yet to hear of a pesticide that has been discovered using the reverse process of getting an end point and working back to a pesticide that will achieve the result required.

Plant researchers are entering into new areas of opportunity. They now have the tools to design and make complicated biological molecules. The discipline is called synthetic biology and offers great opportunities. For instance they are trying to create an artificial system to mirror photosynthesis by stripping it back to a level of basic reactions where much higher levels of energy conversion are possible. In a world concerned about the implications of the current reliance on fossil fuels, the rewards for such an achievement would be huge.

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