Forage maize, with its late spring drilling date, could fill a gap in disrupted arable rotations this season and avoid the risk of further damage to wet soils.

Where waterlogged soils, spring seed shortages and prolonged cold weather have cut cropping options on the eastern side of the country, forage maize is a good alternative to leaving fields fallow.

The ideal time for maize drilling is between 20 April and 20 May, points out James Todd of Grainseed Ltd, who adds that this later sowing window gives soils time to dry out before cultivations.

Providing growers make use of very early varieties bred specifically for the UK, the maize crop can be harvested in time for a following autumn wheat crop, without breaking the rotation, he adds.

“If it’s proving too difficult to get a spring cereal or oilseed rape crop drilled in the next few weeks, it’s certainly worth looking at forage maize and exploring possible markets,” he suggests.

“It can help with blackgrass control and it gives you some extra time to get the field work done,” Mr Todd adds.

Depending on location, two markets are often available – supplying a local anaerobic digestion (AD) plant or meeting the forage needs of livestock producers.

In both cases, varieties that deliver high outputs of dry matter are preferred, with each 1% of dry matter being worth at least an extra £1/tonne.

“Every digester is different so you need to talk to the plant manager. The target dry matter is very important,” he says.

Mr Todd stresses that arable growers will have to balance this requirement with the need to get a wheat crop in the ground in September, so a variety which reaches maturity early is important.

“That’s why they should consider choices such as Coastguard and Picker, which combine early maturity with early vigour,” he says.

Warmer soil conditions are required for the crop and they should have reached 8C for a week before drilling, he adds.

“One of the key considerations with maize is that it doesn’t like soil compaction. So assess the seedbed early and don’t consider minimum tillage if there is any possibility of a cultivation pan,” he says.

Taking a spade is the best way to check for compaction and Mr Todd says growers may have to get land subsoiled to allow the main root of the maize plant to reach deep enough to access water and nutrients.

Maize’s deep root system really helps to open up the soil to the benefit of subsequent cereal crops, he notes.

The main nutrient requirement is for potash, with 240kg/ha being the target. In addition, 150kg/ha of nitrogen will be required, as well as 60kg/ha of phosphate.

Most of these nutrient requirements can be available from organic sources, such as farmyard manure, so growers should check soil indices before applying bagged fertiliser.

“Half of the nitrogen and all of the potash should be mixed into the top soil pre-drilling, while the phosphate should be applied at drilling. The rest of the nitrogen goes on at the cotyledon 2-leaf stage of the crop,” says Mr Todd.

Weed control is usually done post-emergence, with the crop giving an opportunity to clean up resistant blackgrass.

“You can make use of a different active ingredient, such as nicosulfuron. It is an ALS inhibitor, so you need to hit the blackgrass while it is small,” he adds.

There are pre-emergence choices too, including last year’s newcomer Wing-P, although their results are fairly weather dependent.

Growing for biogas

Every AD plant has a different requirement in terms of its feedstock, so it’s difficult to be clear on the best variety to grow.

“The current advice is to produce as much crop as possible, making sure that you have 27-28% dry matter,” Mr Todds says.

Asking what the plant operator wants is essential, he stresses. “Some want high levels of energy, while others are looking for digestible fibre. But dry matter is the key to high methane yields,” he adds.

That’s why growers should aim for dry matter yield, using varieties that suit their region, soils and preferred harvest date.