Monday, May 20, 2019

Time to reflect on best biogas maize varieties

October 1, 2018 by  
Filed under Crops

Varieties that can finish fully in adverse conditions could provide valuable insurance for biogas maize growers next year after a difficult season in 2018.

Choosing slightly earlier varieties than previously thought most suitable for individual locations and conditions could help many growers get more energy from every ha of land, says Lucy Smith-Reeve of seed merchants Grainseed.

“Maximising energy yield/ha is the primary objective of every maize grower producing crops for AD but it’s an over-simplification just to go for the highest yields,” she explains.

“In particular, the more variable growing conditions we now seem to be facing each year must be factored in to provide a degree of risk management.”

Reliable varieties

The decision as to the most reliable varieties to grow is made easier by the fact that many new generation ‘Bred for Britain’ varieties produce yields and energy contents comparable to the highest yielders – without their associated risks.

“It always used to be that if you wanted high yield you had to go for a later maturing variety that had time to build bulk and cob size but this has been challenged in recent years with many earlier varieties delivering similar performances overall.

“But the real difference is that they can do this with significantly less heat units than their later maturing counterparts which is an important difference with regard to the more variable conditions often experienced through the growing season.”

The latest 2019 descriptive list for maize for anerobic digestion produced by the British Society of Plant Breeders (BSPB) more than underlines this, says Ms Smith-Reeve.

“As usual, the list is divided into varieties for favourable sites and less favourable sites – the difference being the amount of heat units available for plants to mature. Drymatter yields are higher overall on the list for favourable sites but the difference is often marginal.


“Three of the top five varieties on the biogas list for less favourable sites are the Grainseed ultra early varieties Ardent, Lovely and Remington which require around 1200-1250 heat units/ year to finish and have been proven over several years to be exceptionally consistent.

“The average drymatter yield for these varieties is 16.6t/ha whilst the average drymatter yield for all varieties on the favourable list is 17.8t/ha – just 1.2t/ha more – but many of these varieties require over 1300 heat units/year to fully mature and therefore present a greater risk.”

Interestingly, the extra early variety Bonnie, which has the highest energy yield/ha of all varieties on the less favourable list at 205,000 MJ/ha is also the third highest performing variety on the favourable list at 213,000 MJ/ha, says Ms Smith-Reeve.

“A variety like Bonnie is therefore delivering 95% of it’s full potential in less than ideal conditions and in good conditions it is within 2% of the highest performer on the favourable list which achieves just 4,000 MJ/ha more at 217,000 MJ/ha.

“Even the really solid ultra early variety Lovely is producing 200,000 MJ/ha in the favourable list and this is one of the most resilient varieties there is.”

Saleable value

Biogas growers should pick their maize varieties with care and think as much about earliness and reliability as outright potential yield to maximise energy production, gas yield and also saleable value.

First, growers want to have a crop to sell, so there’s no point going for the highest yielding variety only to find it is too fragile to pull through any challenging conditions. Some less than hardy crops practically died in the ground this year.

Secondly, growers should focus on a crop that will also deliver the best combination of yield, drymatter and starch content – not just on a crop that will mature properly in their own individual conditions.

When all factors are weighed up, this will inevitably direct growers producing energy crops towards the higher yielding, earlier maturing varieties, believes Ms Smith-Reeve.

Varieties like Ardent, Lovely, Remington, Absalon and Bonnie offer the best combination of resilience and output potential for most growers. Farmers concerned about low rainfall or on exceptionally free-draining soils should consider the extra early variety Marco.

Ms Smith-Reeve says: “It will take 50 or so more heat units than an ultra early to mature fully but it has proven drought tolerance and produced a commendable 202,000 MJ/ha in the 2019 BSPB biogas list for favourable sites.”

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