Bright Maize’s Business Manager, Charlie Dolphin, observes that the maize crops doing best this year are those which were drilled into well prepared seed-beds which held sufficient moisture to support speedy germination and establishment. Such is the importance of drilling to all that follows; he jumps forward to talk about the essentials of good seed-bed preparation for next year’s crop – a subject he believes should never be far away from the grower’s mind.
For more than 40 years maize has been grown in the UK as a forage crop. Its cultivation has become increasingly widespread as farmers have realised the benefits of adding maize silage to the diet of dairy and beef cattle and sheep. It has high and consistent energy and starch levels, and is easily palatable and digestible for ruminant livestock. The potential improvements in milk and meat production from using maize silage make it a highly desirable crop.
However, successfully growing what was originally a sub-tropical plant in temperate Britain does pose challenges. Leading seed breeders like Bright Maize’s partner company MAS Seeds have developed early-maturing varieties that are much better suited to our climate, with improved yields and drought- and disease-resistance. Good crop husbandry is as important as choosing the right seed, with correct spraying and fertiliser application both crucial. But perhaps the most under-estimated aspect of maize-growing is seed-bed preparation. Getting this right is the basis for everything that follows.
A seed-bed that will allow the roots to go deep without obstruction
Like all plants, maize needs the right levels of moisture, oxygen and warmth to germinate and establish itself, and the seed-bed is key to providing this. Maize has a comparatively large seed, much bigger than say an onion seed, so it doesn’t need a very fine seed-bed. What it does need is a deep seed-bed that will allow the roots to go deep without obstruction. Even small areas of compacted soil below the surface will block the young roots and force them to go round, stunting growth and ultimately reducing yield.
The ideal soil for maize is a free-draining medium loam that is easy to work and warms up quickly in spring. The ideal field site for maize is south-facing and below 140m altitude. Heavy clays may be hard to work and subject to compaction, and very light sandy soils may dry out quickly and increase the risk of soil erosion. But seldom does the textbook site present itself, and good crop husbandry and attention to detail can overcome many of the less than perfect conditions encountered by growers. In more marginal areas and sites, growing maize under a degradable plastic film can significantly increase viability and yields, albeit at an additional cost: this is practical for some but not, at present, a feasible option for the majority.
Care must be taken not to overwork the soil
In order to avoid compacting the soil care must be taken when preparing the seed-bed not to overwork the soil, not to work it when waterlogged, and to minimise the number of times the soil is worked. Machinery should have tyre pressure set as low as possible. If there are areas of soil compaction or soil pits which are too deep to be tackled by ordinary ploughing, a subsoiler should be used to break them up.
There are different schools of thought about the best tillage system to use cultivating the ground for maize. The traditional system involves primary tillage, ploughing the land some time after harvesting the previous crop, and secondary tillage, preparing the seed-bed later with harrows or other cultivators. These processes aerate the soil, distribute nutrients effectively and reduce weeds and pests, but can damage soil structure and health, and cause soil erosion.
Avoiding soil compaction
Avoiding soil compaction is particularly important with maize and some farmers now use strip-tillage. In strip-tillage, only narrow strips where the crop is drilled are tilled. This reduces soil movement with benefits for soil structure, but may require hiring specialist equipment, and is less effective at reducing pests and weeds. If soil pans or compaction already exist, subsoiling the whole area may be needed before strip-tillage can be used effectively. Another alternative is no-tillage, where the ground is not cultivated between crops. This means the soil temperature is lower early in the season which reduces maize yields, and is probably most suited for growing maize as ground cover for game. Whatever the advantages of each system, there is no doubt that the trend is towards less tillage, not more.
Once the seed-bed is ready, the crucial question is when to drill maize. The longer the growing season the better the yield, so there is a strong temptation to sow early in April. But maize will only germinate when the temperature is above 8-10 degrees C and there is sufficient water in the soil (maize is highly susceptible to frost damage). So, the best guide is to sow maize once the soil temperature (at 8cm depth) is above 8C for five consecutive days, the weather forecast is favourable (no ground frost on the horizon, and no heavy rainfall before seedling emergence) and the soil is moist enough to enable germination but is not so wet it will compact under drilling machinery. Maize grown under degradable plastic can be drilled earlier when the soil temperature reaches 6 degrees C, no-tillage maize will probably need to be a week later than otherwise as the soil takes longer to warm up.
Some who sowed into dry ground had to resow weeks later
The dangers of sowing before conditions are right have unfortunately been demonstrated this year. For many farmers a wet April was followed by a dry May. Some who sowed into dry ground had to resow weeks later when the original seeds failed to germinate, with extra costs and inevitably lower yields to come.
The other key factor is how deep to drill maize. Too deep delays drilling as the soil temperature is lower, and the emergence rate is lower. Too shallow means seed loss to birds and others. Given an effective bird repellent seed treatment like Korit, a precision drill depth of 4-5 cm is ideal. Bright Maize understands that plans to ban Korit in the UK have been postponed until a good alternative is developed. If no effective seed treatment is available, a deeper drill depth is required – deeper than a rook’s beak as the saying goes.
High-quality seed is nothing without attentive, intelligent and informed crop husbandry
The wizardry of seed-breeding has been invaluable in making maize a viable and important crop in the UK, but high-quality seed is nothing without attentive, intelligent and informed crop husbandry. Getting seed-bed preparation and seed drilling right give the maximum chance of the reward of a fine harvest. Where’s the sense in expecting high-yield results if you don’t get the basics right?