DOES MAIZE MAKE SENSE?
RECENT commentary that maize was a ‘disaster’ in latt er years has prompted some debate about the merits of growing the crop in Ir el and. It c er t ai nl y was a difficult year for maize, but I would wager that it was tough for all arable crops.
Another criticism of the crop is that it has a late harvest, but this is largely dependent on the grower. If the sowing date is early with the correct variety and plastic use, we know that harvest can be finished in October.
Sowing date is also critical in terms of crop grain quality and starch contents.
Total crop drymatter (DM) yields varied with early sowing dates, but grain yield, starch content and DM were always much higher. This, in turn, allowed harvesting to be carried out earlier. Similar results were found by the late Jim Crowley in Oak Park and Dr Lindsay Easson in Hillsborough.
It is also known in some quarters as an expensive crop to grow but costs should be calculated on the tonnes of drymatter (DM) that are harvested per hectare.
Indeed, an allowance should also be made for the quality, which if fac tored in, of ten makes maize cheaper than first cut grass silage.
YIELDS
We estimate that the crop costs €1,600/ha to produce. However, this can be reduced to €1,450 where slurry is used. At this level, the crop is somewhere be tween the cost of smallgrained cereals and root crops such as potatoes and beet.
However, the higher yields from maize compared to smallgrained cereals makes it considerably cheaper per tonne of DM produced.
With an average yield of 12t DM/ha in 2012 and more than 17 t DM/ha in 2013, the crop works out at €133/tDM in 2012 and €94/tDM in 2013. Slurry can reduce costs by another €10/tDM. For comparison, firstcut and second-cut grass silage costs are es timated to be approximately €120/tDM and €150/tDM, respectively.
Not only is it cheap to grow, but we believe that maize silage is unrivalled as a preserved forage for ruminant animals in terms of feeding value. UCD trials from 1982 to 2005 that compared the feeding value of maize and grass silage in the diet of ruminants found that: a) maize silage increased DM intake by 12.5pc and average daily gain (ADG) by 17.5pc, and improved carcase quality of steers; b) maize silage in the diet of cows increased milk yields and proteins; c) maize silage in the diet of fattening lambs increased ADG and reduced time to slaughter. Another concern is the impact of the crop on soil structure, however, there is no evidence to support this. The number of times a tractor appears in the field af ter sowing is small, particularly when compared to cereal crops.
This may explain why one field at UCD’s Lyons Estate grew maize for 12 years without any apparent ill effects. Relatively recently, we surveyed fields in the Cavan and Monaghan area where maize was grown for a number of years.
We then compared these with fields where it was grown for the first time and found that the soil structure was usually better on the continuous maize systems with no apparent plastic residues.
And while we’re on the issue of plastics, research fields at Lyons where the crop was grown for 12 years in succession showed no build up of plastic residues or yield decline.
BENEFITS
The f l i p s i de t o t hi s i s t he significant benefits that plastic affords the crop. In replicated trials at Lyons over a decade in the 1990s the use of plastic (over a range of sowing dates, varieties and harvest dates) (a) increased DM yields by 4 t/ha and in trials between 20002005, measured plot yields of more than 20 t/ha DM were quite common; (b) increased grain yields by 2.3t/ha; (c) increased starch content of maize silage by 6pc. Trials over the subsequent years indicated that pinhole plastic gave an additional 1t DM/ha over complete-cover plastic.
So where can the crop be reasonably grown? ‘A line drawn from Cork city to Drogheda’ is not our experience.
Significant amounts of top quality research work on maize growing and feeding in Ireland has been carried out west and north of this line. In our experience, any soil that is suitable for cereal and other arable crops would be suitable for maize.
We have greater concerns regarding elevations of greater than 400ft rather than soil type, though there are a number of growers producing good crops at greater elevations in the Leinster area
Weed control has undoubtedly become more difficult since the banning of Atrazine, but we believe that the two-spray system of a spray under the plastic at sowing time, followed by another between the rows 5-6 weeks later has solved most of the problems.
Looking to the future, the ability of maize and some maize components to reduce methane production from cattle is a characteristic of the crop that may become much more valuable to the sector in its battle to minimise greenhouse gas emissions.
It should also be noted that animals feeding on maize silage have a lower urine production, r esult i ng i n a s i gnifi c ant reduction in atmospherepolluting nitrogenous gases.