This year’s wheat yields will be...?

6 Jul 2012

I am sorry for the delay in writing this blog. Last weekend we met up with one of our daughters and her family. I think it was our 7-month old grand-daughter who gave me the sickness bug. Let’s say it was not the most successful of weekends away.

Despite feeling rotten (as only a man can) I managed to keep in touch with Steve Dorling of the University of East Anglia by e-mail. The reason for this communication was that on average (there are lots of assumptions in this blog, so beware) the end of June is halfway through grain fill of wheat. Steve had kindly offered to update me on the solar radiation and temperatures during this period (June 10th – 30th). You may remember that I talked of the importance of these two factors on grain fill in my blog ‘A late winner’ a couple of weeks ago.Wheat grain

Well, thanks to Steve, I now have the data for this first half of grain fill from two centres, at Wattisham in Suffolk and Watnall in Nottinghamshire, over the past 10 years.

I’ve compared this data with the regional wheat yields over the same period - my first observation is that in every year, except 2010, there has been typically 10-20% more radiation at Wattisham, near Ipswich, than at Watnall. Not only that - there is less year to year variation at Wattisham.

Steve explained that in the summer there is typically less convection and less cloud development the nearer you are to the coast due to cooler air temperatures; as I write, the sea temperature in the North Sea is still only 15°C!

This may partly explain why the Suffolk Hanslope clay soils yield more wheat than the Cambridgeshire Hanslope soils. Or perhaps that’s insulting the superb agronomic skills of the Suffolk farmer!

The second observation is that the good yielding years appear to have a minimum of average radiation for the site and below average temperatures at night. I emphasise that I’m only talking currently about the first half of grain fill and perhaps I can prepare a blog at the end of grain fill to give a more complete story.

The exception was 2011 - which seemed to have superb grain fill conditions with higher than average radiation and low temperatures at night, but below average yields. I think we all know what happened here - the early spring drought took its toll on the number of potential grain sites.

One of my first blogs a few months ago explained why we got yield responses to chlormequat in the absence of lodging in 2011. This plant growth regulator ensured that more grain sites survived that drought and this resulted in a yield benefit because the grain fill conditions were so good.

So what of 2012? Well, radiation so far at Wattisham has been just less than average for the site. However, radiation at Watnall has been very low, nearly as low as in 2007 (the time of the Hull floods). And, whereas night temperatures at Watnall were high in 2007 they have been low in 2012. Similarly, night temperatures have been low in Wattisham in 2012.

This seems to suggest that conditions for grain fill up to the end of June have been OK at Wattisham, but not good at Watnall. This is providing all things are equal. However, can all things be equal in a year when we have seen a huge challenge from BYDV, lorry loads of black-grass and fungicides only being able to damp down rather than control diseases?