The third article in our KWS-sponsored maize matters series looks at seedbed preparation and offers some expert advice on weed control and nutrient management.
Giles Simpson of Pearce Seeds reports some dairy farms in the South West still have clamped maize left over from 2014, which was generally considered an exceptionally good year for the crop. Nevertheless, compaction problems caused by the bad weather during 2012 have not yet been fully resolved on some farms. He recommends growers in this situation use a flat-lift technique or a sub-soiler, to alleviate compaction down to 10cm below either the min-till depth or the plough pan, as soon as ground conditions are suitable.
Mr Simpson says: “The plough pan must be removed, because maize is a plant which cannot cope with compaction. It should be borne in mind the height the plant attains above the ground is the same as its potential root depth, assuming the root is allowed to grow unrestricted.
“Along with the preparation of a consistent, even seedbed, minimising compaction is the best way to reach maximum yield potential. But it is essential to wait until conditions are right; otherwise the equipment is likely to do more harm than good.”
He usually recommends using a starter fertiliser at drilling. “A starter fertiliser will boost alearly growth; crops which have received a treatment down the spout with the seed are always visibly more healthy and vigorous. The only time when it can be withheld is on land with a high nutrient status, including a phosphate level of four and above. A good starter product should also contain zinc and sulphur,” he adds.
A pre-emergence herbicide is another essential element of good management and has produced a worthwhile return on investment in all his company’s trials, he says. Weed competition will depress yield and an early herbicide will help prevent the growth check which inevitably occurs if weeds are allowed to flourish.
“A pre-emergence spray will also give growers a wider window in which to apply a post-emergence treatment, if the weather threatens to delay the second spray period. Knocking down weeds at an early stage makes it much easier to control their spread later on in the season.”
Neil Potts of Matford Arable also recommends a starter fertiliser, unless the soil is exceptionally fertile. While he concurs a preemergence herbicide is useful for fields with a history of high weed infestation, he believes one, welltimed post-emergence treatment with an effective product may be sufficient on many farms.
He points to a change in the general advice on seed rates in recent years. “In the past, it was accepted high seed rates were suitable for early-maturing varieties and rates should be lowered for later-maturing types,” says Mr Potts.
“Over the past few years, breeders have made great strides in producing early varieties which are also highly vigorous, as well as having good yield potential. Therefore, a seed rate of around 42,000/acre will be applicable to most of the more modern varieties.
“Seed rates for forage maize will also depend on the grower’s overall objective; some will be aiming for high starch content, especially where maize makes up about 30 per cent of a dairy cow diet, for example. The priority for milk producers who use it at a higher inclusion rate will be to maximise fresh weight yields. A high starch requirement should be paired with a slightly lower seed rate, while bulk crops are best achieved with a higher seed rate.”
All the signs are pointing to a season which is marginally later, compared with last year, says Mr Potts. “I would strongly advise growers against getting hung up on drilling dates. Attempting to create a seedbed and sow maize when the land is not quite ready may sacrifice yield and quality.
Nigel Walley of Agrovista points out maize plants can lose 60kg/ ha of nitrogen pre-flowering and that 50 per cent of their total nitrogen requirement is needed postflowering. Therefore, two fertiliser applications can be beneficial.
“Applying the entire nitrogen allocation to the seedbed can lead to a shortfall just before the tasselling stage, when the crop needs it most. Aim to place 80 per cent of the total in the seedbed and the remaining 20 per cent via a foliar nitrogen product, at the 8-10 leaf stage.”
Many growers will be looking to save money, particularly in the dairy sector, which has been experiencing low milk prices, he says. But in difficult times, it is even more important to maximise production, by increasing the plant’s ability to utilise nutrients.
“The same advice applies to choosing varieties,” adds Mr Walley. “The old varieties have become outdated and while they can still deliver yield, the loss in feed value can amount to many thousands of pounds. They cannot hope to match the potential of the newer varieties, when it comes to ME, starch and digestibility levels.
John Burgess of KWS issues a word of caution to growers anxious to get their crops off to an early start.
“This year, we have seen a marked difference between the soil temperature 10cm below ground and surface temperature,” says Mr Burgess. “In the North East, for example, the early April below-ground figure was 8degC, which would be sufficient for the seed to germinate and grow.
“However the surface temperature reading was only 1degC. At this level, there would be a serious risk of heavy plant losses, even to the extent that the crop would have to be redrilled. “We need to think in terms of overall seedbed temperature, to achieve the correct timing.
KWS offers a free, webbased soil temperature service, which provides daily updates, to improve the timeliness of field operations. Growers can enter their farm postcode, to find the local soil temperature range at 10cm (4in) soil depth and on the surface.
The service is updated weekly and runs from April to October. Visit www.kws-uk.com