The correlation between yield and crop biomass: knowledge gleaned from the YEN competition

Last year when I went to the awards day for the YEN competition (very much as an also ran rather than victorious) there was one real take home message – the direct correlation between yield and crop biomass.

The higher the biomass the higher the yield!  This started me thinking on whether or not we were managing our crops to maximise the biomass and quite honestly – we weren’t.  Very often we are holding back nitrogen applications for fear of the crop getting too forward and we are regularly applying growth regulators to keep the crop short.  We have regularly had our best crops after organic manures, particularly sewage sludge, applied to the stubble in the autumn there always seems to be a big yield increase.  This was always put down to the reality that you can’t buy all the goodness contained within these manures from a bag – although I’m sure this is part of it I think there is also the nitrogen element which allows the crop to get relatively lush and forwards going into the spring and maximising the amount of sunlight being intercepted.

So do we need a change of approach?  Growth regulators, nitrogen timing and frequency, plant populations, drilling dates

Would autumn nitrogen make a difference?

Then after this year I have another nugget of information – a figure that I had not heard before but the ‘Holy grail’ is to achieve 30,000 seeds/m2.  If you think about this logically at a thousand grain weight (TGW) of 50 this would give you 15t/ha. At a highly desirable and occasionally achievable TGW of 60 this would equate to 18t/ha – now that would be getting somewhere.

Breaking this down into the basics it is 600 ears/m2 with 50 grains per ear – nothing exceptional there!

Anyway in our YEN crop this year we achieved 29,800 grains/m2 but with a very poor TGW of 40 so the yield was only 12t/ha – which was still our best crop of the year by some margin!  I think that the low TGW was probably down to low light levels during June and fusarium levels of around 25-30% infection.

The real message is get involved – I have found out two really important take home messages that I can use to help assess my crops and hopefully enable me to do the job better!

Find out the next Monitor Farm meeting dates and read Monitor Farm meeting reports:

Tom Bradshaw YEN blog pic 1

Tom Bradshaw YEN blog pic 2



Tom Bradshaw is a partner in his family farm and grows 1,485ha of combinable crops – malting barley, milling wheat, peas and beans - to the west of Colchester in Essex. Apart from a small area of owned land, the majority is farmed under contracting arrangements and includes a wide range of soil types. He has been involved in Recommended Lists trials, and appeared on the BBC Harvest programme in 2013. Tom was recently elected to the NFU combinable crops board.

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