Kaukas Has Topped Northern Ireland Maize Trials

And, there’s no reason why the experiences found in The Province, shouldn’t be repeated in the more marginal regions in England or SW Scotland.

According to Trevor Gilliland, head of AFBI Plant Testing Station at Crossnacreevy, more crops in the Province are now under plastic than are grown in the open and, as a result, maize is creeping west and north into the more marginal areas.

AFBI (Agri-Food and Biosciences Institute) has been trialling crops under plastic since 2001 and there are clear cost-effective advantages in terms of yields and maize quality.

“What plastic does is lift the early soil temperatures,” he says.  “We expect a 10 ^OC increase at the soil surface and a 5 ^OC increase at 10cm depth after planting in late April.

“Plants are under the plastic for about a month before they break through and on average this advances silking by three weeks. 

“This gives you control over an earlier harvest with better DM and starch yields.  Alternatively, you can use later maturing varieties and capture their higher yield potential.”

Last year’s relatively poor season helps illustrate the point.  While early spring conditions were favourable and crops were generally drilled in good time into good seedbeds, summer conditions were very poor with low sunlight hours, restricting growth and yield.

“Looking at control varieties under open cultivation, we couldn’t get DM above 20% and yields were disappointing at 9t/ha from a 30^th October harvest,” says Dr Gilliland.  “Normally we’d expect 12t/ha at 30% DM.

“This compares to yields under plastic in 2007 which were four tonnes higher at 13t/ha, with a DM of 32%. from a harvest that was three weeks earlier.

“As an average over the last seven years we have found that using a plastic mulch has consistently hit the 30% dry matter target for the crop, whereas open grown maize has failed to do so in poorer seasons.  The average plastic yield over these seven years is 16t/ha which is over 3t/ha more than the open maize and most of this extra yield is high value starch.

“As a rule of thumb, plastic pays for itself if it provides 2.5-3t/ha more dry matter, which is clearly possible,” he stresses.  “On top of this is the extra starch production and the greater year to year consistency that the use of plastic provides.”

Dr Gilliland that in practice, growers could gain more from plastic than is found in trial.  “In our work we are comparing like for like varieties, sown on the same day.  However, the use of a plastic mulch gives about 5^OC of frost protection and an earlier silking date. 

“Therefore, growers can opt for an earlier sowing of a later higher yielding variety under plastic to gain a greater advantage of something around 4-5.5t/ha of starch-rich maize silage.  This is what is making the plastic system popular with so many local growers.”

“The benchmark variety under plastic in Northern Ireland has been Justina, but for those who can get in very early on the best sites, it is possible to use the extremely high yielding variety Benicia.  This though is a high risk selection.

“On the more marginal areas, Goldcob is widely used as it still matures and lays down starch under inclement conditions, but has a yield ceiling.

“Goldcob is again the standard under open cultivation in more favourable areas, along with Kingdom and Crown.

“We recommend varieties largely on the basis of their starch yield.  With many farmers feeding a mix of 60% grass silage and 40% maize, we are after a high DM and high starch maize to provide energy as a substitute for concentrate,” says Trevor.

Dr Gilliland says that the new 2008 Recommended List brings a whole range of new varieties into the reckoning, some of which show big advances under plastic.

These include varieties from the KWS stable (Caruso, Kaukas and Salgado), from Pioneer (PR39B50 and PR39R86) and from the French company Caussade Semences (Traddi CS).  All of these will be provisionally recommended for plastic use for the first time on the new Recommended List this spring.

Standing out from this data set is Kaukas with a starch yield under plastic of 123%.  While Dr Gilliland stresses that the results are based on just two year’s data, Kaukas does seem good at laying down starch.  “It will have to have a very bad year in 2008, for it not to become one of the top future varieties under both plastic and open cultivation,” he says.

Alongside these newly Recommended varieties are 13 others that have already been proven to perform well under plastic in Northern Ireland.  These include six varieties in the top ‘Bold Type’ category ( LG3193, Goldcob, Nescio, Goldclamp, PR39G12 and Justina).

There are also 13 varieties recommended for open sown maize, of which there are again six in the top ‘Bold Type’ category (Reinaldo, Leeds, Kingdom, Crown, Kroesus and Ruler).

“The advances we are now seeing in new varieties coming through the system make it important that growers have a free choice to select varieties under plastic,” he says.   “It is important that growers do not simply stick to ‘old-reliables’, but have independent and trustworthy information on what advances are available for our marginal climate,” he says.

For this year, his advice is don’t put your entire crop into a single variety.  This means adopting one of two approaches.

Firstly, mixing varieties in the same field by planting alternate rows of two relatively similar DM and starch content types, but with slightly different silking dates, can reduce the risks of a spell of bad weather spoiling pollination and, as a result, cob fill,” he points out. 

Alternatively, select varieties on a field by field basis.  “Using later higher yielding varieties for your best land and more reliable robust types on more marginal areas, makes the best use of your farms potential.  It is also a good way to try out a new variety from the Recommended List without too much risk.”

Growers can see the complete Northern Ireland Recommended List – which is published later this month - by visiting www.afbini.gov.uk.