The fourth article in our Maize Matters series for 2018 looks at nutrient demand and outlines the principles of a trial to study the effect of row width manipulation.
Experts have long been advising growers to exercise patience when it comes to maize planting. However, the combination of high rainfall and prolonged low soil temperatures left little option but to wait for the correct drilling conditions this season, which is estimated to be at least two weeks behind the norm.
Graham Ragg of Mole Valley Farmers highlights the importance of phosphate, for maximising yields.
“Phosphate is fairly immobile in the soil, compared with many other nutrients, particularly at low temperatures,” he says. “Placing the fertiliser next to the seed is the best way of ensuring its availability; broadcasting is not as effective.”
Potash is another important nutrient for maize and one which is often underestimated.
“Milk producers will usually apply liberal quantities of farmyard manure and slurry to maize fields close to the farm, but areas further away can suffer from a lack of potash. Land which is rented for maize-growing can also be deficient, so it is worth testing soils before planting. Fields lacking in organic manure will usually require chemical potash, which can be used at a standard rate of 180kg/ha.”
In general, the maize nitrogen requirement is applied before planting, but high levels of leaching last winter may justify a ‘top-up’ treatment, advises Mr Ragg.
“Anyone whose maize has not yet been planted could apply 10-15 units/ acre of additional nitrogen, as a safeguard. After emergence, either urea or ammonium nitrate may be appropriate at the 2-3 leaf stage, when it can be used quite safely.
“Foliar nitrogen later on in the season, at the 6-8 leaf stage, can be combined with an eyespot spray, but avoid solid fertilisers after the 3-4 leaf stage of the maize, as they can cause scorching,” says Mr Ragg.
Avoid solid fertilisers after the 3-4 leaf stage of the maize, as they can cause scorching
Drilling got underway in mid-May for the KWS trial to measure the effect on yield of decreasing maize row widths from the standard 75cm to 50cm. The high-yielding variety Amaroc has been planted on-farm adjacent to the KWS headquarters at Lydney, Gloucestershire.
John Burgess of KWS says: “Most UK maize is sown at 75cm row spacings, but this configuration does not allow for a tramline spraying system. To counter the issue, some growers opt to travel diagonally across the field. However, the practice can cause minor damage to the plants, while a 50cm row spacing would accommodate tramlines.
“There is a belief tighter row spacings will necessitate higher seed rates to meet anticipated yields, but seed rate and row width are not, in fact, linked. The lower plant population at the 50cm row width will have the ability to intercept more sunlight and should compensate for the extra space, by closing up the rows.
Varieties with lower tolerance will suffer greater stress in low temperatures, with a negative effect on the root zone.
“I would expect no significant difference in yield, although the narrower row spacing will probably result in taller plants. It will also permit a higher forward speed at sowing, which will be appreciated by growers with large acreages and contractors.”
The difference between maize varieties in 2018 is likely to be less noticeable, compared with previous seasons, predicts Mr Burgess.
“The vast majority of maize has been sown under near-perfect conditions,” he says. “Differences between varieties tend to be more marked in colder temperatures, when types with the highest level of early vigour will flourish. Varieties with lower tolerance will suffer greater stress in low temperatures, with a negative effect on the root zone.”
The KWS maize demonstration site at Lydney will be open to visitors from the end of August until early October. The site includes variety plots, chemical trials, including seed treatment evaluation, and an area for testing both current and new AD maize hybrid performance. Please contact your local merchant to arrange a visit, or telephone head office on 01594 528 234.