Sowing under biodegradable film safeguards forage maize yields in marginal areas Following this seasons maize harvest many farmers are reporting poor quality and low yields as a result of the persistently wet weather and lack of sunshine which prevented crops from ripening fully. But maize growers can limit their vulnerability to another poor harvest next year by growing their forage maize under a sheet of biodegradable film, with those in marginal areas seeing yield increases of up to 50%.

Dr Simon Pope of Wynnstay Arable advises farmers to look carefully at the benefits of this method of growing. Many dairy farmers will have to re-consider their winter feeding regime as a result of this year’s poor maize harvest, and in many cases will have to buy in alternative sources of starch. “In many crops in marginal areas, maize cobs simply haven’t matured properly this year due to a lack of sunshine during the summer. This has resulted in crops that are deficient in energy and with poor dry matter content,” Dr Pope explains.

As a general rule of thumb, maize crops around the UK have typically been three weeks behind schedule due to one of the wettest and greyest summers on record. However, crops that were sown under biodegradable plastic are reported as being much more advanced and have produced far better yields. “Farmers that have grown their maize under a layer of film have seen a huge benefit this year,” Dr Pope continues. “In Ireland the technique is well established with approximately 65% of maize sown in this way. And the benefits are clear to see, particularly in marginal areas where cold conditions and heavy soils can make maize difficult to grow. In these areas yield increases of up to 50% are commonplace.”

Maize seed will not germinate until the soil temperature reaches 10 oC. However, crops that are sown during April will probably go into the ground at closer to 8 oC. The biodegradable film rapidly raises the temperature to 20 oC, acting like a miniature greenhouse and giving young plants a stronger, earlier start. The growing season can therefore be extended as earlier sowing becomes possible. This in turn gives the maize plant more time to ripen fully at the end of the season, Dr Pope explains.

Extending the growing season also allows more photosynthesis to take place, resulting in higher starch yields, with energy levels improved by more than 30%. The crop will also ripen on average three weeks earlier than normal allowing harvesting to take place earlier in the year and thereby spreading the harvest workload.

Sam Shine from maize growing specialists Samco, has over 12 years experience of sowing maize under film in Ireland. His company invented the unique Samco system and he claims that there are additional benefits to the technique. “By using biodegradable films, farmers can use their farm’s own supply of manure to grow higher yielding maize varieties. The increased soil temperature not only improves growing conditions and reduces the risk of frost damage, but also raises the availability of nutrients, with phosphate in particular being more readily available to plants,” Mr Shine says.

This eliminates the need to apply an expensive mono ammonium phosphate starter fertiliser as long as the soil indices are adequate in the first place. Farmers should therefore check the NPK indices of individual fields and assess the nutritional value of their slurry supplies prior to sowing. “Without knowing exactly how much fertiliser is required, there is a risk of either over or under-using fertiliser,” explains GrowHow’s fertiliser advisor, Mike Sheppard. “Either way, farmers will lose money either by over-spending on fertilisers, or by having to buy-in additional feed to make up for poor value, low yielding maize crops. In most cases 50kgs per acre of Early Bite 25.10.0 would provide enough water soluble phosphate to establish the plant and available nitrogen to accelerate growth,” Mr Sheppard adds.

At an additional cost of roughly £90 per acre, the system is undoubtedly more costly peracre than the traditional method of growing maize, but cheaper per tonne of dry matter.

“With fertiliser prices roughly double what they were this time last year, the reduced fertiliser requirements will pay for about half of these additional costs,” explains Wynnstay’s Dr Pope.

“In addition, fewer passes are needed as a pre-emergence herbicide can be applied at the same time as the seed is sown and the film is applied. This one pass operation therefore uses less diesel and can also save in terms of labour requirements.”

Despite being used less commonly in the UK compared to Ireland, the system is increasing in popularity. The UK market is currently expanding by 35% per year, with approximately 10% of the total area of forage maize grown in the UK currently being sown under a layer of film. This includes marginal areas such as Scotland, Cumbria, the South West, West Wales and North Wales, where air temperatures are lower due to altitude or proximity to the coast where night time temperatures can drop significantly. As such, these areas do not lend themselves to growing what is essentially a sub-tropical plant. Increasingly large areas of grain maize are also being grown under plastic in areas such as Nottinghamshire and Kent, where farmers are using the technology to reduce their drying costs.

Growing maize in this way requires the use of specialised maize varieties Dr Pope continues to explain. “A variety that looks good on paper will not perform well if it is unable to break through the film.

“Wynnstay supplies a range of maize varieties and recommends some of those from Pioneer as particularly suited to growing under film,” adds Dr Pope. “We can also provide specialist agronomic advice to farmers who are considering using plastic next year, and after a season such as the one we have just experienced it is easy to see why more farmers should consider using the technology to avoid a second year of disappointing maize production.”

Further information from: Dr Simon Pope ,Wynnstay Arable Tel: 01939 210555

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