8 things to consider before sowing maize

Maize growers who are consistently getting crops off late, struggling with yields, and negatively impacting the environment may be asking themselves whether maize is the right crop for them, or if they could grow it better.

The past two years have proved particularly challenging for maize growers, with late springs, unpredictable growing periods and wet autumns resulting in huge crop variability.

See also: Farmer Focus: Paying the price of variable maize maturity

With the crop increasingly under the spotlight because of the risks of run-off and nutrient leaching from bare winter soils and muddy harvests, the pressure is on the industry to do better.

Kite’s principal consultant, Paul Macer, believes maize remains a good crop to grow on a cost per tonne of dry matter (DM) and feed basis, when grown in favourable areas.

However, he says it is important to review performance and adapt accordingly.

“There will always be challenging years, but if the challenging years are becoming closer to the good ones [in number], it might be worth questioning why you’re growing it,” he says.

For an accurate appraisal, he advises looking at a rolling five- or 10-year average. If performance is consistently poor, or getting worse, practices should be reviewed.

“If you’re consistently only getting 10-11t/acre [25-27t/ha] from maize and you’re making a mess getting it off every year, your cost per tonne of DM does become uneconomic at that stage,” Paul says, adding that costs are the same regardless of yield.

Paul and Neil Groom, general manager for Grainseed and Maize Growers Association council member, advise growers to consider the following points for this year’s growing season:

1. Choice of field

Selecting the right field is the most important decision to make as this will influence the number of heat units accumulated through the year.

Free-draining, south-facing fields that are not too high should always be prioritised. Growing on a steep field with run-off issues is “a complete no-no”.

2. Soil compaction

Dealing with any soil compaction should be given top priority prior to drilling. Failure to do so will limit maize root development and crop growth.

Ideally, any field ruts should be addressed with a tine as soon as possible following a period of dry weather to encourage water to drain away.

If the spring continues to be wet, a plough can be used in April, followed by a subsoiler on top of the plough to break up pans.

3. Maturity class

Rather than fixating on total DM yields, early-maturing varieties should be considered. Freshweight yields may not be as high in these varieties, but starch yields can be good, Paul says.

Early-maturing varieties can also be harvested earlier, which buys time in the autumn. Every maturity class is equivalent to five days’ difference in readiness for harvest.

For example, a maturity class 10 variety will mature ten days earlier than a maturity class 8. Harvesting earlier also creates the opportunity to plant a following cereal or grass crop.

Drilling a crop of Italian ryegrass, Westerwolds or forage rye after maize could provide an early spring bite or silage cut before going back into maize, for example.

4. Use of film

Growing maize under film could also be worth considering in areas that struggle with warmth early in the season.

Maize needs to be drilled into soils that are consistently 8-10C at drill depth at 9am, with decent weather prospects post-drilling.

Film acts like a blanket to help accumulate heat, allowing drilling to be brought forward when ground conditions allow.

Growing maize under film does add cost, taking drilling to about £494/ha, including a pre-emergence spray, Paul says. However, he says in marginal areas “it’s definitely worth doing the maths again”.

Neil explains that combining an early variety with growing under film could bring harvest even further forward.

For example, growing a maturity class 8 variety, instead of a 5 or 6, and growing that variety under film, would bring harvest forward by about three weeks.

However, extremely early varieties do not produce enough yield to justify the increased cost of the film, he warns.

© Tim Scrivener

5. Undersowing and oversowing

Undersowing maize with grass could create better travelling conditions at harvest and help reduce the risk of nutrient leaching associated with bare soils in winter.

Neil advises using a pre-emergence herbicide after drilling maize to create a clean seed-bed. Once the plants have eight to 10 leaves, the crop can be undersown with grass using a specialist drill.

Grass can be undersown at the same time as drilling maize, using slower growing species such as fescues to prevent the maize from being outcompeted.

Neil believes undersowing is more relevant in areas with good rainfall but needs careful consideration in drier regions.

“In Kent, Sussex and East Anglia, where there’s not a lot of summer rain, I’d prefer to use an early-maturing variety to harvest in September, and put a winter cover of grass in, so all the summer rain is used for the maize,” he says.

Oversowing grass (once maize is established) allows more vigorous varieties to be used, such as perennial ryegrasses and Westerwolds.

These also grow better in the autumn, holding soils together and utilising more nutrients.

6. Key nutrients

Applying sulphur to maize ground could help yields and maturity.

A trial at Harper Adams funded by The Maize Growers Association found that applying ammonium nitrate (AN) with sulphur to the maize crop in the seed-bed resulted in 1t/ha more yield compared with straight AN.

The crop also matured more quickly, allowing it to be harvested five days earlier.

Neil says adding phosphate at drilling can also help with early maize growth and root development in soils with lower phosphate indexes of 2.

7. Alternative crops

On those farms struggling to get above 24t/ha of maize, wholecrop cereals may be a better option. These could be grown as an alternative, or as an additional forage on fields less suited to maize.

Including an additional forage in the diet can benefit DM intakes, but ration balance will need adjusting, Paul says. At about 10.2-10.8MJ of metabolisable energy (ME)/kg DM, wholecrop has a lower ME than maize (11.2-11.6).

Starch is also lower in wholecrop, at roughly 20%. Consequently, other sources of energy and starch will need to be added to the diet, such as cereals or high-starch by-products.

The ability to harvest wholecrop earlier than maize, in mid to late July, creates a more favourable weather window.

Weeds can be controlled after harvest and grass re-established to provide a late silage cut or autumn grazing, as well as winter ground cover.

A further option could be to buy maize in from someone who can grow it better, Paul adds.

8. Better quality grass

For some growers, it may be preferable to focus on growing grass silage better and moving away from maize. Good grass silage can deliver more than 11MJ ME/kg DM, with high protein levels.

To optimise silage quality, Paul emphasises the value of a multicut system, where grass is cut as early as possible in late April to early May and then every 28-30 days.

Regular reseeding to maintain grass quality also plays a role.