NIAB - National Institute of Agricultural Botany

Orson's Oracle

I don’t believe it!

Posted on 20/12/2012 by Jim Orson

Jim reaches his half century - the 50th Orson's Oracle

I don’t want to sound like Victor Meldrew but I don’t believe it!  We’d travelled halfway round the world and taken several internal flights around New Zealand and it had all gone like clockwork.  We get back exhausted to King’s Cross and the overhead lines are down in the Hitchin area, arriving back in Cambridge two hours later than we should have.

I went to the very south of NZ’s South Island on one of the internal flights, meeting a farmer with exceptionally high wheat yields but only average yields of oilseed rape. Rape has only been grown there over recent years to supply a bio-diesel plant. The plant is only used to crush oilseeds.

The discrepancy between wheat yields and oilseed rape yields in different countries is intriguing.  The poorer the wheat yields, seemingly the higher the relative yield of oilseed rape. I became aware of this issue when I visited Eastern Europe a few years ago.

In Poland, between 2006 and 2010, the average oilseed rape yield was only 29% lower than that of wheat, with wheat averaging less than 4 t/ha. In the UK and Ireland, we have high average wheat yields with rape yielding around 60% lower. In Germany, wheat yields are not as high as here, averaging 7.5 t/ha, and rape yields are about 50% lower. In the more extreme climates of Canada and Australia, rape yields are only around 30% lower than those of wheat.Oilseed rape

I’m not going to pretend to know all the reasons for this. However, lower wheat yields are often because of drought and/or heat during grain fill. Oilseed rape is earlier maturing and its key yield determining growth stages are earlier in the summer when it is likely to be less hot and dry. I recognise that this is rather simplistic and there could be other explanations.

Whilst flying around New Zealand, I was rather horrified to see the amount of land devoted to so-called lifestyle plots. These comprise a few acres and a very nice modern house. The land is used for horses or trees and does not seem to contribute much to food production. The local farmers are generally against lifestyle plots, unless, of course, they get planning permission for them. I agree that they’re difficult to justify at a time when there is concern over future food supplies.

However, this issue is not confined to New Zealand. Our Peterborough Council wants to cover 99 acres of prime fenland with solar panels. Gone are the days when the Soil Survey graded land ostensibly to ensure that the best land is not used for development. I’d better sign off before the Victor Meldrew part of me comes to the fore.

Best wishes for Christmas and 2013.

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Combating disease and nitrates

Posted on 13/12/2012 by Jim Orson

NZ dairy & irrigation

The weather is now glorious in New Zealand; you can almost feel all that solar radiation swelling the crops. After speaking at events in both the North and the South Island crops look generally well, but spring barley has been a bit slow getting off the mark because of a cool and damp spring. 

The same conditions caused higher levels than normal of septoria in wheat, but they’re still comparatively low by our standards. The main disease threats over here are the rusts; brown rust is just getting going in the current warm/hot conditions.

There is no resistance in septoria to triazoles or strobilurins in New Zealand. Rusts are controlled well with comparatively low doses of fungicides; the programmes advised by the Foundation for Arable Research (FAR), the NZ levy organisation, feature low but appropriate rates of fungicides. 

However, this has caused some disquiet. So in the field days I’ve been attending there have been discussions on both the appropriateness of the doses and the likely impact on resistance. Just like the UK, the recommended doses are based on one application a season of the product whilst in practice multiple applications are made, often in mixture with other fungicides. Hence, it is inevitable that lower than recommended doses are used. In terms of resistance, all the evidence points to higher doses of fungicides resulting in greater selection for resistant strains.

I’ve noted two major changes in farming over here since I last visited in 2007. Firstly, the onward march of dairying. There are a lot more cows in the traditionally arable areas in the country. Secondly, there’s a lot more irrigation, partly because of more cows but also for the arable crops. 

This onward march of dairying may have been halted for the moment. The price of milk is currently below the cost of production, particularly for some of the highly geared new units. Virtually all the milk is dried and exported to Asia. In addition, there is legislation being introduced on nitrates in water that may have a profound impact on dairy production. It may be that cows will have to be housed for at least part of the year in order to reduce nitrate leaching and this will have a significant impact on costs.

Unfortunately, from the perspective of recording to meet the requirements of nitrogen regulations, the arable farmers may bear the brunt despite the fact that arable crops appear to meet the requirements of the legislation. In dairy, there may only be a few different land management units whilst in arable there can be a huge numbers of units particularly on farms where there are small areas dedicated to seed production. 

I hope that sense prevails and arable farmers do not have to spend longer than necessary at the desk and computer to prove that they comply.  An additional complication arises when arable farmers winter dairy stock on forage crops sown for this purpose. It’s up to the regional councils to manage the legislation and there could be very different recording requirements according to locality.

Well, I have to sign off for now as the weather and views outside demand my attention.   

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Hot winds and cold barbecues

Posted on 09/12/2012 by Jim Orson

New Zealand FAR

I gave a few talks at New Zealand's equivalent to the Cereals Event this week - The FAR CROPS Expo, held near Chertsey on the South Island. It was very difficult to prepare the talks because of recent events. The options were, should I excessively gloat about the most recent rugby result or maintain a dignified silence? After a lot of careful consideration I adopted the latter option. The audiences did the same, there was no mention of rugby.

As you know, NZ wheat yields can be very high. I was in a paddock (field) yesterday which yielded around 17.5 t/ha last season. The crop was irrigated, part of the approach that is taken to trap all the solar radiation that they receive during the critical growth stages of wheat. In fact their success can be directly attributed to trapping as much solar radiation as possible by adopting European long season wheat varieties, earlier sowing, disease control and irrigation. The farmers who have been adopting optimum practice for some time now feel that they are beginning to see a levelling off of yields and the annual variations they see can be directly attributed to the amount of solar radiation received during grain fill.

The weather over the last week has been extremely variable. This is not surprising when it is considered that NZ is comprised of two small islands in a big ocean. On the day of the event the much vaunted North Westerly blew with a vengeance. This wind is from the direction of Australia and is hot and dry. It was very difficult to stand at the plots and speak but I was informed that it could have been an awful lot worse. The potential transpiration for that day was estimated to be between 6-7 mm. Farmers quoted 1988 when a North Westerly blew for weeks and completely dried out the cereal crops on the lighter land, resulting in extremely low yields. So it is not surprising that irrigation is a great asset in such a climate.

Before this week the weather has been wetter than average and so the irrigators have only just been switched on. Wheat is at the flowering stage and the crops look magnificent. It could be a very good year if there is sufficient radiation from now on.

I have been on familiar territory on many aspects of wheat production over here. It is easy to pick out Oakley in the untreated variety trials, smothered in yellow rust. What is slightly different is that the amount of yellow rust on Claire is approaching that on Oakley. Claire has been very susceptible to yellow rust for the last six years over here. The tools to control diseases are fairly similar; Seguris is on the market with the SDHIs bixafen (in Aviator) and fluxapyroxad (in Adexar) in the final year of development. What is slightly different is that isopyrazam (which is mixed with epoxiconazole in Seguris) is available alone as Seguris Flexi. This may be because Seguris Flexi is used is herbage seed production. I may return to this in a later blog.

Today is cold (a maximum of 10 degrees Celsius) and wet. Not good conditions for the barbecue I'm attending at lunchtime. It's comforting to know that the English are not alone in having barbecues in the rain.           

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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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