Thinking about Maize

Maize harvest 2020 summary

Although harvest might not be quite over for some, it is an ideal time to start thinking about maize options for 2021 while it is still fresh in most people’s minds.

After a very wet winter leading into a wet spring, timing of drilling was crucial. Maize under plastic managed to get off to a great start, making the most of the available moisture, and the benefit of the warmth. It wasn’t too long ago, back in May where there were concerns of frost damage to the crop – this seems a very distant memory after the recent hot weather!

Reports of very different maize growth have been coming in, all dependent on the time of drilling. Variable soil conditions, rainfall and sunshine hours, have also led to vast differences in crop quality and harvest date. For most, harvest will have started now, with some already finished. Making a good harvest plan is crucial, particularly in years like this with many crops differing in localised areas.

Variety Choice

As trends suggest that the seasons are getting more unpredictable, with warmer/drier periods followed by wet seasons, this might indicate that earlier, quicker growing varieties are more suitable. For sites that are prone to the wetter weather and waterlogged soil, these earlier varieties can be established later (into the warmer soils), require less heat units to mature, and will be at the right dry matter for an earlier harvest. There will be sites that can cope with a later harvest, making the most of the big bulky varieties these tend to produce.

Variety choice is not only down to qualities or yield desired from the final crop, but also the site selection. In an ideal world, the site will be south facing, below 600ft above sea level, good amounts of topsoil and a pH of 6.8. This might be achieved in some situations, but maize can be grown in many other situations, with good agronomy and management practices. Soil temperature at drilling is key, 8° for lighter soils and 10° for heavier land. Conditions will vary from site to site, which should be looked at in individual circumstances.

There will also be environmental considerations to take into account when choosing a site to grow maize. Fields with steep sloping banks are not best suited, particularly in years like this year, with bouts of heavy rainfall, after prolonged drought. This can lead to soil erosion and nutrient run off, neither of which is good for the environment or the field. Under sowing the maize or establishing a cover crop immediately afterwards are two possible solutions to this…

Grass and cover crops after maize

Establishing a crop directly after maize harvest allows for several opportunities. It utilises the productive ground for the winter months by retaining nutrients, boosting soil organic matter, and reducing soil erosion over winter. Depending on the crop chosen, an extra forage crop can be achieved, in what would otherwise be bare stubble. Options can include:

·         Follow maize with a winter cereal

·         Forage rye

·         IRG

·         Westerwolds

·         Cover crop

Why under sow?

Under sowing the maize crop can solve issues with trying to get a crop established late on in the season, particularly when weather conditions have been unhelpful. The time of drilling will dictate the species that can be used. Early drilled crops will require a less competitive species, such as a fescue, to not out-compete the maize. Later drilled crops will require a species with a more vigour and rapid establishment like an Italian ryegrass to not be outcompeted by the maize.  Under sowing should be done in early June when the maize is at the 4-5 leaf stage. Additional benefits of having an under sown crop is being able to move in the field better during a wet harvest.

Broadcast or drill?

Establishing a grass or cover crop after maize can be achieved successfully by broadcasting or drilling. Most cover crops should be drilled as this increases seed to soil contact, thereby bosting establishment. This is especially important with early, less prolific mixes and can be easily achieved using a conventional drill. Cover crops should be spaced 10-20 cm from the maize row to avoid competing with the maize crop later mixes can be broadcasted later as they are quicker to establish.

Harvesting Maize

To achieve the best nutritional results maize should be harvested at the optimum dry matter (DM) content of 30-33%. To determine whether the crop is at the correct stage for harvesting, a visual assessment of the ‘Milk Line’ can be made.

The ‘Milk Line’ distinguishes between the hard, yellow starch part of the grain and the soft, white, (milky) starch part. As the grain matures, the milk line descends towards the centre of the cob and the proportion of hard, yellow starch increases. To achieve 30-33% DM maize silage, it is recommended to harvest when the milk line is halfway down the grain.

If the crop is harvested when the milk line is only ¼ of the way down, estimated silage DM will be 28-30%. Below 30% DM; Lactobacillus bacteria must generate higher levels of lactic acid to stabilise the silage, to achieve this they must consume more sugars which results in a nutritionally poorer and more acidic silage. Furthermore, Clostridia bacteria prefer these wetter environments and instead of lactic they produce butyric acid; this is a weaker acid which prevents silage stabilisation enhancing the risk of silage deterioration and DM losses.

Harvesting with a milk line ¾ of the way down will produce a DM silage of over 35%. Clamp consolidation is burdened when maize is harvested above 33% DM which will facilitate oxygen contamination causing silage deterioration and DM losses. Furthermore, the higher proportion of hard, yellow starch will reduce its digestibility and may pass directly through the animal.

Nutrition

Working example:

A 45t/ha maize crop at 30% DM will yield 13.5t DM/ha.

Losing only 1% of this DM equates to 135kg DM.

In a diet containing 25kg/cow/day of fresh maize silage, 135kg DM would feed 18 cows. At 30litres/cow and 28ppl, this is the equivalent to losing £151.20/day.

Over a 180day winter this equates to a potential loss of £27,216.

DM losses will increase the further it deviates from the 30-33% DM recommended range. Achieving silage stability and maximising nutritional value is thus of paramount importance and can be achieved with the aid of Pioneer 11C33.

If you have any queries, you can contact our experts.

Seed: 01243 755620

Crop nutrition: 01243 755730

Animal nutrition: 01243 755761

Or you can email our team at info@bartholomews.co.uk