The fourth article in our 2015 series discusses how best to bring maize on in the current climate.
Weather patterns for the previous two years have made maize growing reasonably plain sailing, with tremendous yields recorded right across the country. Despite conditions this spring posing more of a challenge, there is still every chance crops will catch up before harvest.
Prolonged spells of low temperatures, coupled with relatively low rainfall, have combined to make it difficult for growers to make decisions on drilling and management. Heat unit figures have been below average for the year and 2015 records so far have shown a much wider gap between night and day temperatures, compared with recent seasons.
It is too early to predict whether conditions to date will delay harvest and/or have a negative effect on yields. However, getting on top of weeds at this stage is crucial as maize reacts badly to competition. Control is a key factor affecting crop performance and that is why Graham Ragg, of Mole Valley Farmers, recommends the use of a preemergence herbicide.
“It is a false economy to leave out a pre-em spray because it will reduce weed burden and may allow rates of post-em treatments to be reduced by as much as half, in some cases. In addition, weeds which are left to grow on will have taken up a considerable amount of nutrients, as well as moisture, from the soil.
“It is not easy to get the herbicide spray timing right, especially if the weather is changeable. The revocation of grandfathers’ rights for spraying, which is being introduced this November, has led to some of the older farmers leaving spray treatments to local contractors. This can affect timeliness of operations and I expect the trend to increase once the regulation comes into force.”
There is a much wider choice of herbicides suitable for today’s maize crops, compared with the products which were available in the past, he adds. That can make it difficult to decide which treatment is best, so he advises growers to take expert advice, to ensure money is spent on products which are right for the individual farm situation.
Weeds to look out for include orache and mayweed, with annual meadow-grass often widespread in maize within grass rotations. Second year or continuous maize is particularly vulnerable to nightshade, he says.
When it comes to maize fertiliser trends, most of today’s crops receive an application of mono-ammonium phosphate (MAP) or di-ammonium phosphate (DAP) and Mr Ragg favours a treatment with either product down the spout.
“In an effort to save on inputs, some producers have opted to reduce fertiliser levels at drilling. In my opinion this is unwise, as maize performance relies on an adequate supply of all the major nutrients. Available phosphate in particular has a very positive influence on early vigour. “
I prefer DAP, as it contains slightly more nitrogen than MAP. The only time I would suggest fertilisers can be reduced at drilling is when the soil phosphate index is 3 or above.”
Farmyard manure and/or slurry also make a valuable contribution to maize nutrient requirements, he adds. If they have not been applied, or where additional nitrogen is needed, a balancing, seedbed-incorporated fertiliser is essential.
“Maize is like an addict; it needs a fix and this is supplied in the form of nutrients applied at drilling. One of my clients experimented on a 20-acre field, with half given a MAP fertiliser down the spout and the rest left untreated. The treated field produced an increased yield of three tonnes/acre.”
He is a great fan of the variety Kougar, from KWS. “Kougar is an exceptionally good variety and has performed well consistently year after year, no matter what the circumstances. I have clients who tried other varieties last year and even with the highly favourable growing conditions, they have returned to Kougar, largely for its reliability and exceptional performance,” he says.
Growers may wish to take advantage of KWS’ free web-based soil temperature service, which provides daily updates, to help with the timeliness of field operations.
Growers simply enter their postcode to receive information on their local soil temperature range at 10cm (4in) soil depth, as well as on the surface. The service, which is updated weekly, runs from April to October. Visit www.kws-uk.com