As always, there are two separate recommended lists for maize – one for planting in the open and another for varieties suitable for planting under plastic.

Both lists are separate and are not directly comparable with each other. While there is no variety common to both lists, certain characteristics, other than yield, make varieties more or less suited to either system.

It must also be stated that the vast majority of the total area is now sown using plastic cover in an effort to combat the less favourable growing years and ensure better feed quality than might be available from planting in the open.

That said, it remains important to select the variety that best suits your specific situation.

So, if you are planting in the open you will need to choose a variety with higher relative starch content for more marginal situations and only plant a low starch variety in the more favourable sites which combine high soil fertility, minimal soil damage and a south facing aspect.

The recommended lists

After a number of years of relatively unsuitable weather and disappointing yields, 2013 provided a critical break for the crop.

Good yields and good silage quality prevailed and this proved so important in a year where additional acres were planted to help redress the fodder shortage that lasted all through last spring.

We must wait to see what will happen in 2014 but there is no reason to believe that planted area will drop, despite the good grass year in the second half of 2013 also.

Over the past number of years, plastic cover has shown its worth and this is reflected in the increasing grower preference to plant under plastic.

In this regard, it is perhaps strange that only three varieties are recommended for use under plastic, while we have eight recommended for planting in the open.

But the swing to plastic use has only manifested itself in the market in the past three years and it takes the same length of time to alter the direction of the recommended list and this will obviously alter in time also.

In choosing a maize variety, there are many important considerations. While variety is one of these, the field remains the most important.

A poor or unsuitable field will grow an equally disappointing crop of any variety. Many maize fields have been hammered to death in recent years, mainly as a result of spreading slurry in unsuitable wet conditions.

These fields may perform okay in a very good growing season but they will be affected much worse in a challenging year. So start with the field and get the fertility right.

Variety and system choice is then important. Any type of marginal site (aspect, geography, altitude, etc.) needs plastic cover to ensure adequate silage quality.

Yes, you might get away if it’s a good growing year but can you afford the low yield and poor quality if it is not?

The recommended list tests the performance of varieties across a number of sites over a number of years.

Genetic potential and suitability continues to improve, as witnessed by the appearance of new varieties over time. The recommended list aims to find the best and safest varieties for farmers.

Maize for silage is used for its energy value in the diet. In recent years, this has been measured and expressed at metabolisable energy (ME) value for each variety.

The intention is that net energy will be presented in time but this has not been measured for enough years to allow it to be expressed as a value on the recommended list.

In the meantime, the ME value represents the usefulness of each variety to the animal or the end user, as distinct from the grower. It is useful in terms of identifying the value of the whole silage, rather than just the grain, and varieties differ in this respect.

Increasingly, varieties are showing different digestibility characteristics in the non-grain portion of the plant.

It is suggested that a 0.5 ME unit is equivalent to one litre of milk per day per cow.

So, for farmers growing their own feed or where there are grower user partnerships, the ME value must be used and balanced against yield and starch to give the optimum return to both parties.

Sowing in the open

Details of the recommended varieties and their characteristics are shown in Table 1.

The data is based on results of trials carried out over three years in the period 2011 to 2013. Adept, Andante and Fergus have been dropped from this list this year.

Varieties without plastic

Acclaim (R):

Has the lowest dry matter yield but the highest dry matter and starch content. So good quality silage when grown in suitable areas. It is very early maturing and dries down very early. It has a high ME value. It has the shortest plant height. Bred by Limagrain and handled by Goldcrop.

Ambition (PR-1)

New on the list this year with provisional recommendation. It has very high relative yield, good DM levels and good starch content. So it looks like a versatile variety and very early maturing. And it has exceptional ME value. Also bred by Limagrain and handled here by Goldcrop.

Atrium (PR-2)

Remains provisionally recommended with very high yield potential, good starch but low dry matter content. It also has a very high ME value. It is regarded as late maturing. This one is also from Limagrain but is handled here by SeedTech.

Beacon (R)

Has high DM yield potential, average dry matter content but with good starch content. It is tall, has a good ME value and is medium to early maturing. Another Limagrain variety handled by Goldcrop.

Beethoven (R)

Very high yield potential at 112 but with only moderate dry matter and starch content. It is late to dry down, is medium to late maturing and tall. ME value is well below average. Needs good growing sites. A Limagrain variety through SeedTech.

Destiny (R):

Has average dry matter yield but with high dry matter content and high starch level. It dries down early and is early maturing. It has a good ME value. Another Limagrain variety through SeedTech.

Kougar (R):

Slightly below average yield potential with average dry matter content and above average starch. It is medium to early maturing but is on the low side for ME value. It was bred by KWS and comes through SeedTech.

Kroft (PR-1):

New on the list with below average yield potential. But it has very high DM and starch content. An early maturing variety. It has an average ME rating and is relatively short. This one was also bred by KWS and comes through SeedTech.

Varieties for planting under plastic

The recommended list for planting under plastic is a separate list and is not directly comparable to the variety list for planting in the open.

The control data in Table 2 shows that the plastic system is leaving higher yield, higher dry matter and higher starch levels, compared to planting in the open (Table 1), to help pay for the additional cost.

Crops grown under plastic produce more consistent yield and quality from year-to-year, as the plastic tends to reduce most of the adverse effects of poor growing conditions.

The ability of plastic to artificially heat up the ground earlier and possibly lengthen the growing season enables the use of later-maturing, higher-yield potential varieties to be sown under plastic.

Surprise has been dropped from this list this year.

Varieties for under plastic

Award (R):

High yield potential with high dry matter and very high starch content. It is medium to early maturing with very high ME value. Of the three recommended varieties, it takes longest to break through the plastic. A Limagrain variety through Goldcrop.

Justina (R):

Continues to show very high yield potential but its dry matter and starch content are only moderate in comparison to Award. It has good ME value and is medium to late maturing and benefits from early sowing. It is very fast to come through the plastic. Bred by Pioneer and handled by agents.

Tekni (R):

High yielding variety with good dry matter but below average starch content. It is medium to early maturing, quite fast through plastic and has good ME value. It is bred by Caussade and handled by Goldcrop.