Hutchinsons trials are shedding new light on how growers can maximise the returns and rotational benefits of energy maize.
Interest in the crop has increased dramatically with the expansion of the biogas sector over recent years, with some 52,280ha of maize grown for AD last year, equivalent to almost one third of the total maize area.
The Hutchinsons trials at Great Livermere near Bury St Edmunds were set up to address the lack of impartial agronomic advice for energy maize and have already revealed some significant findings that will push crop performance forward, says the firm’s Kiryon Skippen.
A notable example is the comparison of narrow 500mm row spacings with the standard 750mm width traditionally used on many farms. Trials have dispelled fears that narrow rows compromise root growth, and have in fact proved the opposite to be true.
Crops sown on narrow rows last year produced marginally bigger root balls that penetrated to greater depth than the conventional spacing. Plants were better able to access and retain moisture and nutrients, resulting in improved cob development and higher yield, he says.
Sowing rows closer together also maximises land use efficiency, as research shows root balls of plants sown at wider spacings fail to fill gaps between rows, resulting in some 15% of the field being under-utilised.
Weed control is improved at narrower row widths too, as the extra crop competition results in fewer, smaller weeds.
Protecting soil integrity
Another area being investigated is the benefit of under-sowing maize with a cover crop to protect the light sandy loam soil from erosion and leaching over winter after maize is harvested.
A grass and legume mix was broadcast into plots when maize plants were around knee-high, allowing enough time for the cover to establish properly while not competing with the crop.
“The cover grows underneath the maize and is ready to grow away as soon as the maize is cut, protecting the soil over the winter before a following spring crop is sown,” says Mr Skippen.
Indeed, improving soil health and nutrient availability throughout the season is a key aspect of managing “hungry” maize crops and other trials show significant benefits from using the N-Lock nitrogen stabiliser to prolong nitrogen availability within the rooting zone.
Used in conjunction with Efficient-28 slow release fertiliser and an azoxystrobin + propiconazole-based fungicide spray at growth stage 32 timing, the approach better matches the ongoing nutrient demands of growing maize plants than the sudden spikes associated with conventional fertilisers.
The approach is being repeated this season, with additional trials looking at how varying zinc and potash applications affects final yield.
A separate variety screen is also in place where 16 new and established energy maize varieties are being compared to see which offer the most consistent performance and help growers decide which could work best in their situation.
All plots are taken through to harvest, when crops are fully analysed for a range of factors from dry matter content to methane yield.
The ultimate aim, Mr Skippen says, is to help energy maize growers improve variety selection and crop agronomy to maximise biogas yields on every hectare grown.
Look for performance consistency over multiple years
Several varieties offer higher yield and energy output
Spread risk with a range of maturities
Narrow 500mm row spacing:
Improves access to water and nutrition
Improves water infiltration
Gives more, bigger, fuller cobs
Increases dry matter yield
Results in bigger root mass, and
Bigger, fuller cobs – emphasised in a late season dry spell
Plants stay green for longer, especially during drought conditions.