Correct soil pH is of the utmost importance for making the most of a chose variety, says Steven Gate of Agrovista.
“It is virtually impossible to grow a satisfactory crop in soils outside a pH range of 6.5-7 and levels below pH 6-6.5 will have a detrimental effect on yield. This is mainly linked to the reduced release of phosphate from soil, which is essential for strong early growth and development.”
“The importance of soil pH and the nutrient indices required by maize mean soils must be analysed before seedbed preparation. The ideal time for sampling is late-January to February and before farmyard manure or slurry is applied.
“The type of lime required should be determined by the magnesium index of the soil,” he says.
If the magnesium is high – index 4 or above – this may reduce the availability of potassium to the maize crop, in which case calcium lime would be a better option.
“In cases where the soil pH is too high, there is an increased risk of the ‘locking up’ of micro-nutrients, such as manganese, copper and zinc. This may need to be rectified by applying a foliar treatment.
“Working backwards from the soil analysis will give growers an accurate nutrient requirement plan, which is essential to deliver optimum yields and quality from forage maize. Potash, in particular, is a nutrient which is very often overlooked.”
For Mike Corp of Chemega, taking time to prepare the seedbed correctly will pay dividends.
He says: “The seedbed should be as fine as possible, but without the risk of moisture loss, although I admit this is easier said than done.
Maize looks strong, but it is actually a rather weak plant. It cannot withstand competition from weeds and the best way to control them is to create a fine tilth, with a good level of moisture. Under these conditions, an application of herbicide will work to its maximum level of efficiency, as the product will readily attached itself to the soil particles.
“Compaction is also one of the maize plant’s worst enemies, because it will prevent the roots from moving freely, as well as limiting access to water and nutrients. This situation will often result in a ‘dwarfed’ crop.
“Sub-soiling, ploughing and letting the winter frosts break the soil down are all excellent methods of creating a suitable seedbed. It is not cost-effective to try and save money by making one pass with the power harrow, for example, when the seedbed would benefit greatly from two passes,” he says.
It may be worth taking a fresh look at seed rates, according to John Burgess of KWS.
“Advances in plant breeding, coupled with farm machinery developments in recent years, mean seed rates for many of the newer varieties can be reduced. This will save on input costs and maximise starch content. On average, a grower using the newer varieties could potentially reduce seed rates by 2,000 seeds/ha, which would give a saving of about £8-£15/ha.
“It is false economy to switch to a cheaper variety. Admittedly, the newer varieties are slightly more expensive, but they are highly vigorous and therefore fewer seeds are required; some crops achieved 98 per cent establishment rates last year. New varieties can also be harvested earlier, when conditions allow,” he says.
“Modern equipment, like the Kuhn Accord, the Vaderstad Tempo and Amazone’s ED precision drill, has also increased the scope for seed rate reduction, by improving the accuracy of seed placing. These machines use air at high pressure to push the seed down the coulter, making sure it is uniformly positioned along the row. This kit is expensive, however, so a contractor may need to be brought in.”
Lower seed rates are associated with an increase in starch production. The potential for cob fill is greater, because plants have more exposure to sunlight. They also benefit from reduced competition, compared with crops sown at standard rates.
“The best way to work out seed rate is to take a required plant establishment rate of 105,000 plants/ha, for example, and add a figure for predicted losses. This would be about 2 per cent, in a reasonable growing year and where more modern varieties are sown,” he says.
Brendan Paul of Agrii emphasises the importance of maize row spacings, which he believes are set too wide on many farms.
“There are great advantages to be gained by using narrow row spacing,” says Mr Paul. “The range of drills available in the past meant row spacing was generally fixed at 75cm. However, more modern cutters give greater flexibility and can cut across the rows, if required.
“My recommendation is to fix row spacing at about 40cm. As the canopy grows, it reduces the amount of light available at ground level and that helps to suppress weeds. This effect is reached within a shorter time, where narrower row spacings are adopted. It will also help to minimises moisture losses.
“In addition, narrow rows reduce inter-plant competition; when this practice is adopted, each plant gains greater access to both light and nutrients.”