Producers harvesting tall or later maturing maize this Autumn should consider cutting their crops a little higher than usual, according to trials carried out by the MGA and Grainseed Ltd.

Each extra 30cm of cutting height increases crop dry matter and starch content by around 2% outweighing any associated loss of freshweight yield, the work suggests.

And with many parts of the country experiencing exceptionally tall crops this year, growers should cut for quality safe in the knowledge they will still be harvesting high yields, advises Grainseed technical director Neil Groom.

“Many producers from mid October onwards face the dilemma of whether it is best to go for the highest number of tonnes in the pit or aim for better quality forage at the risk of yield,”

“It’s an easier decision when you’ve got a really good quality crop which combines high starch levels with a good D-value at 30% dry matter, but with later maturing crops it is always a judgement call.

The MGA/Grainseed work looked at the relationship between quality and yield in relation to different cutting heights from the lowest possible to leaving 90cm of stubble above the ground.

At the first trial in Broxton, Cheshire, each 30cm of additional height improved dry matter by 1.7%, starch by 2.4% and D-value by 2, but although freshweight yield was reduced by 4.7 t/ha, only 7433 mj/ha of energy were lost overall.

Subsequent trials at Lackham College, Wiltshire, with very high yielding crops, delivered similar improvements in starch content, drymatter and digestibility.

The benefits occur because the plant stores energy as starch in the grain and the lower part of the stem is more fibrous with much lower digestibility, Neil Groom says.

“The trials suggest there is far more to gain from cutting later maturing crops higher in terms of extra quality than is lost through the associated lower yields. Each 1% rise in digestibility alone compensates for a 3 – 4% decrease in yield.

“You may lose on average 5 – 7 t/ha of freshweight yield for every 30cm of extra height you cut, but this is more than compensated for by the extra forage quality and potential milk production.

“The benefits are especially relevant if you are one of the many producers looking at maize plants 8 – 9 feet tall this Autumn as there is a real opportunity to achieve outstanding yields of the highest quality.”