After few false starts in spring, soil temperatures in the UK should be into double figures in early May and on a steadily rising trend, meaning conditions will be optimum for drilling maize.
As farmers are challenged more and more by reg- ulation and reducing numbers of active ing- redients, there is a need to focus on how the tools which are available to grow competitive and resili- ent maize to maximise profitable yield can be used to best effect.
To this end, Syngenta has worked with the Maize Growers Association (MGA) over a number of years to understand the specific needs of maize growers.
MGA’s Simon Draper has been an expert in this field for a number of years and shares some insights on arguably the most important phase of growing the crop: the establishment phase.
Mr Draper suggests delaying drilling until the soil temperature reaches 8-9degC. He says growers should care- fully consider the spacing between seeds, as this will affect the volume and quality of the crop.
“As you increase the seed rate, the size of the maize plants will increase, but cobs will be smaller as they compete for light. This results in the leaves and stem accounting for a greater proportion of the plant by weight.
“It also means yields will increase, but will influence the quality of the crop, as the starch content will drop, even though volume of crop per hectare increases.
“For dairy farmers only growing a small quantity of maize within a largely grass- based diet, this will mean a reduced starch value, so they should be opting for a lower seed rate.
“Where dairy cows are fed a higher maize content in their diet, they will be able to cope with a lower quality feedstuff.
“If farmers are growing maize for biogas production, they are likely to be more inter- ested in the volume of the crop, so drilling plants more closely will result in more plant material. Starch will be diluted as the cob size reduces.”
There has been considerable debate around row width and Mr Draper suggests an optimum row spacing of 50-75cm.
He says: “To maximise overall yields, farmers should consider drilling rows closer together, but ensuring the spa- cing between seeds is uniform both along the length of rows and between rows. It is vital to give plants enough room to grow up.
“Drilling rate has little effect on weed control in the early establishment phase, but the quality of drilling will help counter competition between maize plants and will help maize plants germinate and emerge uniformly.
“If the emergence of one plant is delayed, it will out-compete another, which may then fail and this will lead to a loss in yield. The most common cause of delayed emergence is drilling too fast. The rougher the seedbed, the more slowly the seed should be drilled.
“If maize seeds are drilled too fast, it is likely they will be drilled at different depths, which could result in a yield reduction of 30-40 per cent.”
This year’s dry conditions mean drilling depth should be dictated by where mois- ture is within the soil profile.
Mr Draper says: “Before drilling, farmers should go into the field and dig a hole to find out where in the soil profile the moisture starts, then drill down to this depth.
“It may be necessary to drill a little deeper this year because of dry condi- tions. This may also reduce seed preda- tion by birds.”
Providing the right nutrition to germin- ating and establishing maize crop is vital, according to Mr Draper.
He says: “Maize requires 180kg/hec- tare of potassium, 40kg/ha of phosphate and about 150kg/ha or less of nitrogen.
“If a field has received a large amount of manure or slurry and phosphate and potassium levels are high, there may be no need to apply more.
“Phosphate is really important, as it encourages early spring growth, but it does not necessarily translate into higher yields at harvest.
“Three-quarters of the quantity of nitro- gen should be applied in the seedbed with the remaining quarter applied onto the plant when it is at the first leaf stage.
“Larger quantities of nitrogen applied to the crop could result in a leafier crop with smaller cobs. Farmers looking for a large amount of starch in their silage should consider reducing the amount of nitrogen applied.
“Sometimes when soil temper- atures are low, the maize crop may appear slightly yellow, which is due to a nitrogen deficiency, but as soon as soil warms up, it will release more nitrogen and the crop will regain its colour. There is no need to rush to apply more nitrogen if the correct rate has been applied initially,” Mr Draper says.
NICK Stevens farms two separate holdings totalling 972 hectares (2,400 acres) and grows winter wheat, winter barley, spring barley, oilseed rape, temporary grass and beans and maize across both holdings.
One of the farms is home to a 270- cow dairy herd and some of the 109ha (270 acres) of maize is fed to them as part of a total mixed ration, with the remaining maize being sold off farm to other dairy farmers across Wales and the South West.
Soils vary across both farms, but are generally clay loam overlying chalk and Mr Stevens points out ‘moisture is key’ to cropping success.
As a consequence, he has adopted a minimum or no tillage approach to estab- lishment for all crops, including maize.
He says: “On lighter land, we will add the maximum amount of farmyard manure we are allowed to. We will then run through it with a shallow cultivator to a depth of 4cm, then a grassland subsoiler to remove any compaction.
“We use a Sly Stripcat drill, which we ori- ginally bought to drill oilseed rape, but it works a treat for maize. We drill into a flat firm seedbed, which means when it comes to harvest time, maize foragers do not sink in and the soil hardly moves.
“We drill rows at 65cm intervals, so we end up with eight rows across five metres, but our seed placement is a little bit hit and miss, so we get some bunching of plants, but this does not seem to affect yield.
“Maize looked fantastic last year, despite the drought, and our yields on the heavier land made 37-44.5 tonnes/ ha, and between 24.5-30t/ha on lighter land. Quality was also consistently good, at about 12 ME.”
This year, Mr Stevens has drilled during the last weeks of April, holding off a little as temperatures fell back dur- ing the first half of the month.
He has subsoiled everything to ensure maize plant roots can get down to the moisture in anticipation of a dry summer.
He says: “We are aiming for a low input crop so we do not use a pre-emer- gence spray, but we aim to apply the post-emergence product in mid-May at 100 litres/ha to remove weeds before the four-leaf stage. We are looking to achieve better establishment and less weed competition by farming smarter.”
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