Forage maize growers are recognising the appeal of early maturing varieties as they seek to counter challenging harvesting conditions and consequential soil damage.
Wetter autumns have caused severe soil compaction and waterlogging in many regions where maize is harvested late in the season.
Accelerating the harvest date by drilling a variety that matures earlier is a solution for many growers, but with over 33 varieties on the less favourable area lists alone, selecting one that suits the farm and the livestock system can be confusing.
Independent agronomist Simon Draper says the first point farmers must consider in their selection strategy is whether the crop needs to be high in starch or bulk to meet the needs of their feeding system.
“The rule is if you are feeding more than 50% maize silage the crop needs to be bulky and if you are feeding more than 50% grass silage, starch is the priority.”
Starch formation is concentrated in the grains of the cob, therefore, starch levels are greater when there are more grains and less plant material.
“Care has to be taken not to get the crop too dry because as the crop dies off lignin levels increase which cattle find almost impossible to digest,” says Mr Draper.
Early maturing varieties such as Kaspian and Activate are designed to die off rapidly. Care must, therefore, be taken to ensure that these are harvested at the right dry matter level as they can dry down much quicker than the normal 2% per week when close to harvesting.
Mr Draper says it is a sensible approach to choose a variety that can be harvested in September, when fields should be at their driest. “If the farm has a risky situation, such as a light soil type and a slope in the fields where maize is being grown, avoid a late harvesting crop.”
For a September harvesting window, Mr Draper recommends scrutinising the Maize Growers Association rankings and selecting a variety that scores 9 or higher.
“Once farmers know what they require from the harvesting window and crop maturity, the varieties can be narrowed down to 10 or 15. From these, they can then select for yield, crop standing power and what varieties have worked on the farm previously.”
Early maturing varieties that achieve 34% dry matter or higher at harvest are recommended for growing in most areas of the UK.
Variety selection is critical to feed value and output and fundamental to this process is understanding farm specific circumstances.
Joanna Matthews, Forage Crop Specialist at NIAB TAG, says this process can also aid crop management and potentially mitigate environmental concerns such as soil damage from late harvesting.
In its variety advice to members, NIAB uses a points system which allocates a score by taking into account location and also growing conditions such as soil type and rainfall. Once the performance potential of the farm is established, this should produce a subset of varieties to select from.
“No variety is perfect and typically a compromise has to be made, therefore, a farmer’s priorities of yield and quality characteristics are also key to selection,” says Dr Matthews.
Breeding is consistently pushing performance barriers and responding to the market, and this includes developing earlier maturing varieties. Sergio KWS, Emblem, Sunlite and Exxtens were added as First Choice varieties to the current BSPB Forage Maize Less Favourable Descriptive List.
New additions on the Less Favourable Descriptive List offer a range of characteristics to suit growers needs, says Dr Matthews. She highlights Sergio KWS as a good all-round, relatively early maturing variety which combines quality with an excellent early vigour score.
“Early vigour is a valuable trait on less favourable sites due to the shortened growing phase,” she says.
“For growers on less favourable sites, looking for highly digestible and good quality silage, Sunlite and Exxtens may be a suitable option as they have ME levels of 11.59 and 11.41, respectively, MJ/kg DM combined with a highly digestible stover at 58.7 and 58.3% cell wall digestibility.”
At a yield of 106% of the control, Emblem combines high yield potential with a high starch content of 33.6%, ultimately equating to valuable high starch reserve silage.
While earlier maturing varieties allow for earlier harvesting and a higher starch content, they produce a lower dry matter yield, says Ken March, ruminant nutritionist at Countrywide.
He warns against harvesting a low dry matter maize silage with high starch levels because of its detrimental impact on rumen pH and animal performance.
“Aim for a maize silage with a dry matter within a range of 33% to 35%, and a starch content of 33% plus,” advises Mr March.
“This will allow high levels of carbohydrate to be fed and will produce high energy value for animal performance. Making the right choice can have a positive impact on the herd so farmers should take advice and consider their options.”
(Source – http://www.fwi.co.uk/livestock/tips-on-selecting-which-forage-maize-varieties-to-grow-in-2015.htm)