NIAB - National Institute of Agricultural Botany

Orson's Oracle

Damage limitation

Posted on 07/02/2013 by Jim Orson

I know the precise date when I first saw a television picture. It was 24th March 1951. How do you attribute this amazing display of memory? As is often the case, it is by association with a particular event. Our brand new 12 inch set was first switched on during the 1951 boat race and we witnessed Oxford sinking.

Another event from years ago that I remember seeing on TV was the great flood in Essex. This occurred precisely 60 years ago and there was a huge loss of life. It is surprising that those living in vulnerable properties were not warned to move out. I say this because I used to advise in North East Essex and a local farmer told me that he was in Harwich at low tide that fateful day and the water was already level with the top of the quay. However, I am experienced enough not to judge others on today’s standards. Hence, I shall not be apologising for recommending isoproturon for black-grass control in the past despite today’s knowledge about its possible impact on water biodiversity.

There were hundreds of acres of farmland inundated by the sea. In Essex, this was the old National Agricultural Advisory Service’s finest hour. They supervised the application of gypsum to overcome the impact of the salt on soil structure. They worked long hours and became skilled not only in getting the right quantity of gypsum to the right location but also in making sure that application was to the highest standard. Within a handful of years, soil structure was restored.

The muddy aftermath of the battle of Passchendaele’
The muddy aftermath of the battle of Passchendaele

Of course soil structure can be badly affected in other ways. A good example is sugar beet harvesting this winter. There are fields out there that look like the photos of the aftermath of the battle of Passchendaele; a muddy and pot-holed landscape. In this case, the pot-holes have been caused by tyres and the even deeper ones by digging out vehicles.

The debate is what to do with these fields. How do you repair the damage? Perhaps the right question is what do we have to do in order to assist nature in overcoming the problem as quickly as possible.

There have been a series of meetings recently, sponsored by HGCA and Catchment Sensitive Farming, on repairing soil structure. The talks featured more general drainage and machinery issues and not the specific issue of the extreme damage done to some fields because of late harvesting of root crops. However, I was able to chat about this with the speakers after one of the events.

The context of the discussion was of course to find the most cost effective way of doing this over the next couple of years. Naturally, the ideal solution is to wait for the soil to dry out (assuming that we are bound to have a long dry spell at some stage this summer) and then to move the compacted layers as little as possible to ensure that nature can take its course. The latter will entail establishing a cover crop.

However, this will mean no crop in 2013. Hence, in discussion, a more pragmatic solution was agreed upon; an approach that many farmers have adopted in previous years. The first thing to accept is that leaving such an uneven surface will mean the lowest points (the ruts) will take for ever to dry out. Hence, despite all the potential downsides of running even more tyres (or hopefully tracks?) across the field, the land should be cultivated, just deep enough to lift the shallow ruts, as soon as possible in order to level the soil surface. Once it becomes sufficiently dry, a crop should be established after using shallow cultivations to prepare a seedbed. However, in the most extreme cases of soil damage it may perhaps be more judicious to sow a cover crop (e.g. mustard, fast growing grass) instead, particularly if the soil cannot be moved until very late spring.

Obviously the resulting crop is not going to be great but at least there will be something to sell and its roots will start doing the job of restoring soil structure. The crop choice is probably limited to cereals in most cases. After harvest, provided the soil is sufficiently dry, then deeper cultivations or sub-soiling or moling may be required to help restore structure. The decision on the depth of these cultivations will depend on the observations made after digging a few holes during the summer or immediately after harvest.

Observations of the aftermath of the wet winter of 2000/2001 would suggest that some soils will take perhaps a good two crop years before they are back to where they were before the damage caused by the late harvesting of root crops this winter. This is part of the inevitable cost of root crops and one that should never be discounted when doing crop budgets. The salutary fact is that many experts are saying that we will have to expect more extreme weather events in the future. So it is worth observing and recording the results of trying to overcome the problems caused by the wet root crop harvest of 2012.

Leave a comment / View comments


I am not App.y

Posted on 30/01/2013 by Jim Orson

The relatively warmer weather tempted me out this morning to glyphosate the extension to my allotment. It is currently lawn and killing the grass before digging will save an awful lot of summer weeding. The App. on my phone suggested that I had seven hours before it rained but it badly let me down as it rained only four hours after spraying, so I didn’t get the desired six dry hours. On the other hand, typical of most gardeners, goodness knows what dose I used but it will have been way above that used by farmers.Cambridge weather app

Getting rain when it’s not expected is typical of a wet spell. The opposite is also true; the expected rain never arrives in a dry spell. During the very dry three months of spring 2011, my App. always promised rain in four days time! As they say in Norfolk “it never rains in a dry time”.

The continuous wet weather reminds me of the winter 2000/2001 when we also had huge amounts of rain.  I also recall the repercussions of that wet winter.

The feature of spring 2001 was widespread sulphur deficiency. This may have been due just as much to the dry spring that year as to the wet winter. It occurred in situations where it hadn’t been seen before. 

Luckily, or wisely, we took the decision to apply sulphur to all our trials. This was despite the fact that previously, we only treated the oilseed rape trials with this nutrient. The only trial we didn’t treat was one investigating plant nutrients in winter barley where the application of sulphur would have compromised a couple of treatments. However, we should’ve applied sulphur to it and accepted that we would not get all the information we originally intended. The sulphur deficiency was so bad that the yields from all the treatments were all over the place and we got no useful information at all.

The results of our nitrogen dose experiments in winter wheat were very interesting in 2001. The results suggested that higher optimum doses were not required despite the additional nitrogen leaching and denitrification that must have occurred over that winter. The levels of soil mineral nitrogen in the spring were on the low side but not exceptionally low. Again it shows that soil nitrogen supply is not a great guide to choosing what dose of nitrogen to apply.

The difference between the very wet winters of 2000/2001 and 2012/2013 is that the latter also followed a very wet summer. Waterlogging last May and June resulted in some areas losing a lot of nitrogen to denitrification.  Will this mean that we shouldn’t be comparing the experiences of 2001 with applying nitrogen this spring? I’m not sure and I suspect nobody knows but we will always be wiser once we see the trial results from this year!

No doubt there will be a lot of pressure to apply all kinds of trace element treatments to crops this coming season. The usual argument will be used, “why spoil the ship because of a halfpenny of tar?”. The experience of 2001 suggests that there will be no increased risk of micronutrient deficiency, so buyers beware!

Well, it has stopped raining. There wasn’t a great amount and my glyphosate application may not have been wasted after all. I say this in the knowledge that there was research at the Weed Research Organisation that concluded that the activity of glyphosate was actually increased by 0.5 mm of rain shortly after application. Perhaps I can forgive my App.?

Leave a comment / View comments



Posted on 22/01/2013 by Jim Orson

A blog I wrote last May was titled “Infamy” after the great line for Kenneth Williams in Carry on Cleopatra, “Infamy, infamy, they have all got it in for me”. The blog was about the persecution of glyphosate by the anti-GM movement.

Well, the persecution is unremitting. Perhaps in many ways this could be good news. The protesters have thrown all they can at GM glyphosate tolerant crops and yet the worldwide adoption (excluding Europe!) of this technology increases significantly with each passing year. So now those who oppose it have fixed their sights upon the non-GM part of the issue, the herbicide glyphosate.

It reminds me of the advice given out to Americans and Australians during their gold rushes: the only sure way to make money out of a gold rush is to sell pickaxes.

The constant stream of negative statements appears to be having some effect. Some leading farmers are saying that they want to cut down the use of glyphosate because it reduces soil health and affects biodiversity: both aspects feature strongly in the anti-glyphosate literature.

Personally, I have no objection to cutting down on the reliance on glyphosate, particularly when direct drilling is adopted. This is the arable situation where we would expect herbicide resistance to develop most rapidly, because there is no seed shed in previous years being returned to the soil surface layers by cultivations. Hence, there is no slow down in the process of selecting for resistance.

However, to reduce glyphosate usage based on the evidence presented by the anti-GM movement is another thing. The protesters may be quoting scientific papers, but some of these have been authored by those who appear to share the same view. The recent scandal about GM maize apparently causing cancer seems to come into this category.

The protesters may also be quoting results of experiments done by objective scientists but who espouse their own personal interpretation of the results. An example of the latter is a paper published by a researcher from Rothamsted in the 1970s. In this experiment, a very large population of common couch was treated or not treated with glyphosate shortly before winter wheat was established. The winter wheat got more Take-all where glyphosate was used. The simplistic interpretation is that the glyphosate use was the cause of the additional Take-all. In reality, the researcher proved that the glyphosate killed the couch rhizomes but not the Take-all on the rhizomes so it moved to the wheat.

Finally, the anti-GM lobby may well be quoting the results of good experiments but the treatments are not directly related to what will occur in commercial practice. They may be laboratory based experiments or field experiments that use far higher doses than those used in practice.

Due to the charges made by the protesters, there have been reviews of all the available data on glyphosate. One was written for the US Department of Agriculture which concluded “scientific accounts about increased plant disease and mineral nutrition problems in GR [glyphosate resistant] crops are based on publications from a limited number of researchers. In the context of the entire body of relevant science, the significance of these reports is questionable.”

Another review paper concludes “although some laboratory tests have shown effects on nitrogen-fixing bacteria and soil fungi, effects are typically observed only under artificial laboratory conditions and at glyphosate concentrations well above normal field application rates”.

Finally, a review on the impact of glyphosate on biodiversity concludes “In summary, the literature supports the conclusion that non-target arthropods are at minimal risk from glyphosate and its formulations in offsite areas. Within treated areas, applications of the herbicide can produce changes in species diversity and in population size and structure for beneficial insects through modifications of available food sources and habitat.” 

So, the major impact of glyphosate on biodiversity is that it kills vegetation, i.e. what we use it for in Europe.  When used in GM glyphosate tolerant crops its extra efficacy may have some effect on biodiversity. However, sympathetically managed the opposite could well be true.

The associated issue is, if not glyphosate use in order to kill annual weeds prior to drilling...what do we use? Adopting additional cultivations may have a much more negative impact on the environment and the soil. In Europe the only alternative non-selective herbicides are diquat and glufosinate but neither is as effective as glyphosate on grass weeds. In addition, glufosinate is under risk of withdrawal in Europe because it may exceed some of the hazard criteria that are now being used in the registration process.

Although I will stand accused by some of being a ‘Monsatan lackey' or following my own agenda, I would rather back the views of mainstream science.

Leave a comment / View comments


Across the pond

Posted on 22/01/2013 by Patrick Stephenson

Northern Regional Agronomist Patrick Stephenson guest blogs from the US

Patrick StephensonLast week I was in the company of Blaine Viator at the Association of Independent Crop Consultants (AICC) annual conference. Blaine is an independent crop consultant from Louisiana specialising in sugar cane and is the current president of the National Alliance of Independent Crop Consultants (NAICC) in the USA. This week it was my turn to fly to the States to their national meeting. Leaving behind 25 cm of snow and flying to 20°C in Jacksonville Florida was, I must admit, appealing.

I now know a good number of their members so it’s really nice to get back up to speed with farming events in the US. Firstly we dealt with the drought, which in the mid-west was very bad for the second year in a row; however many growers had crop insurance.

On quizzing them about crop insurance I was given an hour long lecture on how this worked which, in short, is private and subsidised central government insurance based on achieving historic yields. Most growers take this out and as a consequence did reasonably well.  America, being huge, had a huge variation in weather last year; Louisiana has an annual average rainfall of 2,470mm (100 inches) but this year that figure was passed by September! Add to this - last week 430mm (17 inches) fell and you start to grasp the variations within the country.

Cotton and sugar have taken big price drops which is bad news for us in the UK as growers are turning to wheat as an alternative crop. The south eastern states below Virginia can grow winter wheat and soya in one year. Winter wheat, which is seen as a cheap crop to grow, is drilled in October harvested in June and then soya is planted for harvest in October. Although yields seldom exceed 5t/ha prices exceeding £200/tonne mean that double cropping with soya bring greater and easier returns than cotton and maize.

US agriculture

Genetically modified (GM) crops cannot be avoided as a topic; largely as I look with envy at the thought of glyphosate-tolerant wheat for black-grass control. Unfortunately that horse has bolted in the States and widespread resistance is common. Multi-stacking genes is the next approach combining 2,4-D resistance with glyphosate resistance. This does have a high cost and many growers believe pre-emergence sprays are a more cost effective option. Sugar cane growers turned down the opportunity to use GM to ensure that European markets remained open. Blaine believes this was certainly the best thing they have done.

Potato production is dominated by McCain, Frito Ley and a huge Canadian starch producing company. They have blocked all GM development due to public perception. This is all well and good, but the Bt Colorado beetle resistant crops required no insecticide in a season compared to weekly sprays in the non-Bt crops. Are the public aware of this? I think not! Blight resistance is a much more difficult beast and although genes are available the consensus is that these will only have a brief shelf life as resistance will develop very quickly.

Sorry but it is back to the conference our American cousins love 7.00 am starts.


Leave a comment / View comments


Wrong assumptions?

Posted on 16/01/2013 by Jim Orson

Once the New Year is over, farmers’ thoughts turn to nitrogen applications (amongst many other things). NIAB TAG has become particularly interested in nitrogen dose since the introduction of NVZs, increased nitrogen costs and the full realisation of its environmental impact.

In the first couple of years of cross compliance there were many queries from members on the dose of nitrogen for wheat following oilseed rape. The then RB 209 (7th edition) stated that the dose should be as low as 100 kg N/ha following a dry winter and this was the value used by The Environment Agency inspectors to check compliance with the NVZ regulations.

It was clear to everyone that this recommendation was far too low and that following it would lead to sub-optimal crops and margins. To give The Environment Agency credit, they also soon realised that this recommendation was far too low and their inspectors accepted higher doses where justified.

The most recent (8th) edition of Defra’s RB 209 significantly increased the recommendations for wheat following oilseed rape but the issue rankles with advisers and farmers who still consider them to be too low.

One basic assumption in RB 209 is that 100% of Soil Nitrogen Supply (SNS = Soil Mineral Nitrogen plus N in the crop in February plus any allowance for mineralisation) is used by the crop but only around 60% of the applied fertiliser nitrogen is utilised. There are historical reasons for assuming 100% efficiency of use of SNS. In former years, there was more organic material in soils that would release nitrogen during the season, but those days are long gone. Nowadays the majority of arable land has lower organic matter levels and does not receive organic amendments and manures.

This assumption means that for every additional kg/ha of SNS, the recommended dose of applied nitrogen is reduced by around 1.5 kg/ha. Hence, after crops that may leave higher nitrogen residues, as assumed after oilseed rape, the recommended optimum applied dose for feed wheat is reduced disproportionately.

NIAB TAG approached HGCA with its concerns and they financed two projects on the subject (HGCA Project Report 490 - establishing best practiced for estimation of SNS and HGCA Research Review 58 - SNS testing: practice and intepretation). The field studies concluded that the efficiency of use of SNS is typically much less than 100%. In fact, my analysis of the data generated in the field studies suggests that it is below 50% for long term arable soils that do not receive organic manures or amendments.

This means that instead of reducing the applied N dose by around 1.5 kg/ha for every additional unit of SNS the figure may well be around 0.75 kg/ha. I’ve tried this with a retrospective look at around 70 NIAB TAG nitrogen dose trials in wheat that have taken place over the past 10 years or so. These were all carried out on long-term arable soils where no organic manures or amendments were used.Spreading fertiliser

The conclusions are firstly that the Field Assessment Method in RB 209 provides a more accurate prediction of the economic optimum for feed wheat than using the SNS measurement method. Secondly, the accuracy of predicting the optimum is improved by changing the recommendation tables on the basis of an assumed efficiency of use of SNS of 50% rather than 100%. However, this is still no more accurate than using one fixed amount of nitrogen in all the trials!

The most disturbing element is how bad all the recommendation systems are, only predicting within 50 kg N/ha of the optimum in around 60% of the trials. Obviously, we’re a long way from an accurate prediction system. There may be many explanations for this and perhaps this is a subject for a future blog.

At the moment, we have to be content that progress has been made and I hope that the results of the two HGCA funded projects are incorporated into the next version of RB 209. At least it will allow us to catch up with, amongst others, the Australians and the New Zealanders who have for sometime been assuming an efficiency of use of Soil Mineral Nitrogen of between 30-60%.

Leave a comment / View comments


Page: ‹ First  < 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 >  Last ›