The second article in this year’s Maize Matters series covers fertiliser planning and issues to consider, when choosing varieties.
Most experts agree a starter fertiliser will help to maximise the yield and quality potential of their maize, but there are a number of options available and John Burgess of KWS has strong views on the subject.
“It had been standard practice to apply a di-ammonium phosphate (DAP) starter fertiliser at drilling until a couple of years ago, when we saw a move towards a cheaper system of using the lower rates associated with branded micro-granular products, like Umostart and Optimaize,” says Mr Burgess.
“This was mainly due to DAP price volatility and the drive to cut ration costs. “However, the original system was popular because it worked very well and there has been a return to the practice. Mono-ammonium phosphate (MAP) fertiliser has also been used in the past. It may be slightly cheaper, but it is less effective than DAP and has therefore remained out of favour.”
A DAP starter fertiliser is usually applied at 125kg/ha and placed about 5cm below the seed, he says, although a lower rate can be used in certain circumstances. “A reduced DAP rate of 90-100kg/ ha can be used for late-season drilling when the soil temperature has risen to 10-12degC. Otherwise, there is a risk plants may suffer scorching.
The application rate can also be trimmed back on farms which adopt a 5 per cent cut in seed rates, in order to manipulate plant populations. It should be applied ‘down the spout’ and placed about 5cm under the seed.
“Nitrogen is obviously important, but phosphorus is also essential for producing a healthy crop, especially at three to six leaves when the developing root is nourishing the young plant and the nodes and leaves enter a period of rapid growth.
At this stage, plant population density is being fixed and any deficiency will cause the leaves to turn purple, with a negative effect on yield,” says Mr Burgess. Procam’s Guy Peters warns against the dangers of an over-supply of phosphate.
“It is a waste of money to apply phosphate to any soil with an index of more than three and this is also relevant on farms which drill later in the season as uptake will be greater in warmer temperatures,” he says. “This type of opportunity highlights the benefits of soil testing before drilling.
“Environmentalists have expressed their concerns over the potential damage caused by phosphate runoff, especially on fields which are adjacent to water courses. We have all heard of nitrate vulnerable zones and it is possible that phosphate vulnerable zones might be introduced in the future, especially if we do not act now to prevent the risk of pollution.”
When it comes to varietal choice, Mr Peters favours earlies.“The overall aim should be for crops to reach 33-35 per cent dry matter by the end of September,” he says. “This will help to ensure a successful harvest and limit the risk of soil damage.
Therefore, it is best to push for the earliest variety which will suit the farm and drill it as early as conditions permit. A long period of growth will encourage the crop to accumulate dry matter and lay down starch.” Another tip is to prioritise high dry matter figures, he adds.
“When choosing a variety, dry matter yield should take priority over projected fresh weight tonnage, because maize silage with a high water content is more likely to over-ferment and become acidic, which is not good for ruminants.”
“The use of film on maize should be considered, if the dry matter targets are unlikely to be achieved due to the farm situation, or where an early harvest is a priority, in order to avoid soil run off and to establish an early crop of grass or cereals.”
Brendan Paul, of Agrii, stresses that the level of maize silage inclusion should be taken into account, when selecting a variety.“Dairy farmers who use maize silage at an inclusion rate of more than 50 per cent should pick slightly later-maturing varieties which will produce bulk yields and relatively low starch.
High levels of starch carry the risk of acidosis. It may be necessary to add straw to the diet to create a better environment in the rumen. I cannot see the point of growing a high starch variety and then having to add a low feed value ingredient like straw, as a balancer.”
|Nutriant||Typical crop offtake|
|P||70 - 90kg/ha|
The recent ban on chlorpyrifos, the active ingredient to combat wireworm, has had a significant effect on maize in the rotation, says Mr Paul.
The pest, which attacks maize roots and can cause heavy losses, is difficult to control without the use of chemicals. Sales of the thiacloprid-based seed treatment, Sonido, continue to rise, as it is currently the only chemical treatment left available to maize growers.
He recommends that a separating crop is sown, between maize following grass, because the wireworm thrives in established grassland. Another rotational solution is to grow wholecrop cereals, such as rye or winter barley