Maize silage: Keep a close eye on crop maturity

Brian Reidy reports significant variation in the maize crops he has walked this week

Crops are a mixed bag this year for a variety of reasons, mostly drought-related but not exclusively.

As we head into September, and sufficient rain has finally fallen across most of the country after an exceptionally dry summer, attention will continue to focus on preparing for housing and the winter-feeding plan. 

Grazing conditions are excellent at present, and patience is needed with regard to reducing the supplementary feed in order for the farm to grow sufficient grass.

If you reduce feeding too fast, you will go around the farm too fast, and, as the days close in, you will not be able to bank grass.

Maize silage harvesting close in many areas

I have, like every year, been asked to assess the ripeness of maize crops. Crops are a mixed bag this year for a variety of reasons, mostly drought-related but not exclusively.

There certainly was no lack of sunshine during the summer, but other issues have popped up that have had an adverse effect on yield and quality.

A significant amount of maize in the South-East has been harvested or will be very soon, while crops in the Midlands and West are a few weeks away.

I walked 11 crops of maize in one day recently in South Tipperary and North Cork and the variation was interesting. Some were excellent crops that were still fresh and green and approximately three to four weeks from harvest.

In other crops which will need to be harvested in the next 10-12 days, it was obvious insufficient nitrogen had been applied at setting and the crops had run out of steam, with narrow stalks and average cobs. 

In other sites, we saw seeding rates which were far too high, resulting in extra plants fighting for the nutrients, and again the crops ran out of steam and have dried down early, with poorer yield and quality potential. 

This was seen in both under film and open maize. You must feed the crop enough, and we really need to make sure contractors know what the optimum seed rate is.

Growers will need to review all aspects of growing maize before planting in 2027. Fertiliser required taking account of slurry or other organic material, appropriate variety for your site, correct seed rate, sowing date, film or open drilling. As I have already said, most crops will be harvested within the next four weeks.

Ideally, you must allow for cobs to mature to optimise starch yields. However, you must take account of total crop dry matter as the important harvesting parameter. If you delay harvesting too long and the maize is too dry, then you will have lost digestibility, and the crop will be much more likely to spoil in the clamp.

What to consider when walking your crop?

The most important thing is that maize is harvested at a suitable stage of ripeness to optimise quality and performance. It really is worth getting advice regarding the correct time to harvest.

Some key things to look for when you are walking your crop include:

• Current weather and future weather forecast;
• Growing conditions throughout the season;
• Sowing date;
• Plastic or open;
• Variety;
• Cob ripeness;
• Site-soil type/aspect;
• Presence of disease;
• Nitrogen applied at planting;
• Stage of breakdown (Is it brown/yellow or still all green?);
• Ground conditions
• Has it been hit by frost? (Not likely this year!).

Correct ensiling of maize

Harvesting immature maize will result in the runoff of effluent from the pit, and most of that effluent will be valuable starch. In my opinion, the ideal dry matter for maize from both feeding and clamp management is between 28% and 32%.

Any drier and it becomes difficult to manage at feed-out. Harvesting maize simply because you or your supplier wants to plant a winter cereal is not a good enough reason to harvest.

Wastage at feed-out can be a huge financial cost with maize silage. This is easily avoided with good management. Maize is high in energy and if it is not consolidated and managed well in the pit, will result in moulds and spoilage on the shoulders and feed face. 

Toxins, bacteria and moulds will feed on the high-energy material, potentially causing large amounts of waste and poor animal performance.

Ensure it is ensiled and covered properly, and if you will be feeding out into warmer weather next year, then consider an additive. I would suggest an inoculant designed for high dry matter material should be considered at harvest. 

The best additive I have seen includes two strains of bacteria to reduce the pH in rapid steps and also includes antifungal potassium sorbate, which prevents secondary heating and keeps the clamp face cool and fresh at feed out.

• Brian Reidy is an independent ruminant nutritionist at Premier Farm Nutrition. His column features in the Farming Examiner every Thursday.