Patience will be the main quality required on farms which still have maize crops to drill this season. Experts agree forcing a seedbed on land which is too cold and lacking in oxygen will only store up problems for the future. Nevertheless, waiting until soil temperatures rise may mean growers in marginal areas or on heavy land will be left with only a short drilling window.
On farms where seedbed preparation has been delayed, the key will be to oxygenate soils, many of which are still suffering from compaction caused by the prolonged wet spells over the winter. The situation is further complicated because some fields have yet to fully recover from the soil structure damage inflicted by the bad weather in 2012/2013.
Giles Simpson, of Pearce Seeds, says a deep-tine cultivator can be used to open up soils which are still very wet below the surface, with the first pass at about 12-15cm (5-6in) and a second, if necessary, going a little deeper. A flat-lift-type machine is not recommended, as it will create a smear effect and will not rectify the problem, he says.
When it comes to drilling depth, he believes decisions should be based on soil type.
“Maize seeds must have access to moisture, so there is no point in drilling to 5cm on light land, if the soil has dried out. On heavy land, the average depth should be about 6-7cm.”
Tackling weeds in the growing crop is becoming increasingly difficult, as a number of active ingredients in the pre-emergence group of herbicides have been withdrawn from the market, observes Mr Simpson.
“The herbicides we have available do not always control the wide spectrum of weeds growers would like and they also tend to be expensive. However, I would advise the use of a pre-emergence treatment containing pendimethalin, for example, followed up by a post-emergence spray, on fields with a record of heavy weed infestation.
“It is becoming more common for producers to grow maize on rented fields away from the main holding and I would also use a pre-emergence herbicide in this situation, when growers have little or no information on the land’s previous history,” he says.
Neil Potts of Matford Arable concurs with this opinion and points out a pre-emergence herbicide will give extra protection, if post-emergence treatments fail to achieve a successful result.
“If all goes well, then a post-emergence treatment should be able to eliminate a high percentage of weeds in the crop,” he says. “But conditions are not always ideal and bad weather may prevent the post-emergence application going on at the right time; weeds in maize can quickly get out of control and will reduce the quality of the crop.
“Post-emergence timing can also be tricky on farms which rely on contractors for herbicide application and under these circumstances, a pre-emergence spray is usually advisable.”
Seed rate choices will vary, according to location and height above sea-level, but Mr Potts suggests most growers will opt for the average of about 103,700/hectare (42,000/acre). A slightly increased rate may be required on hilly land, to ensure establishment levels meet expectations.
Decisions on whether to use a starter fertiliser will largely depend on the availability of farmyard manure and slurry on individual farms, according to Agrovista’s Nigel Walley. He recommends growers with no access to these materials have soils tested or use a starter fertiliser, which will act as an ‘insurance policy’. This advice will also apply in situations where phosphate is lacking.
The increasingly large acreage of maize grown for energy use in the east of the country, where there is a limited supply of slurry and farmyard manure, will particularly benefit from the use of a starter fertiliser. But soils with a phosphate index of three and above may not need any additional treatment.
“The main benefit of starter fertiliser is to provide a source of readily-available phosphate and other nutrients, which in turn’ will promote root growth,” says Mr Walley. “Healthy roots will greatly improve the plant’s ability to withstand drought, cold temperatures and prolonged wet periods after planting.
“However micro-granular products, which contain additional elements, as well as nitrogen and phosphate, consistently show establishment benefits in difficult conditions. This type of product will require specialist machinery, due to the relatively low recommended application rates.”
Fields with a phosphate index of below three will usually benefit from treatment with a DAP or MAP-type product, he adds.
“The only exception would be in cases where later drilling is planned and where soil temperatures are above average, thereby increasing the availability of phosphate reserves. Even in these situations, care must be also be taken, to ensure sufficient seedbed fertiliser or slurry/farmyard manure has been applied, to satisfy the crop’s nutrient requirement.”
If starter fertiliser is applied to only half of a field, it is very easy to spot the difference between the untreated and treated areas. The treated crops would show a much more vigorous early growth pattern, although this result does not necessarily translate into a yield benefit, he warns.
While Mr Walley concedes a small percentage of farmers stopped planting maize after the ‘challenging’ season of 2012, these were mainly confined to the more marginal areas, he stresses.
“Maize continues to be unmatched as a dietary ingredient for high-yielding dairy cows, as well as being the primary feedstock for the many anaerobic digesters in operation,” he says.
A post-emergence herbicide with a new active ingredient will be available to UK growers for the first time this year, says John Burgess of KWS. Marketed by Bayer CropScience, Maister (foramsulfuron + iodosulfuron) is designed to control some of the most problematic grass and broad-leaved weeds in maize, including fat-hen, dock seedlings, cranesbill and black nightshade. It is also claimed to be effective against black-grass, which is a growing concern due to herbicide resistance issues.