Maize a tough crop to harvest so care pays…

21 August 1998

Maize a tough crop to harvest so care pays…

How different are the

requirements of a forage

harvester when its time to

bring in maize?

Geoff Ashcroft sought

some timely advice from a

Bucks contractor

HARVESTING maize is not simply a matter of swapping the foragers header and then charging round the field.

There are considerable machine adjustments which must be made to get the best out of your maize and machine, explains contractor Mark Richardson.

"Get it right and the results make growing maize more than worthwhile. But get it wrong and the forage will hold little digestible value for even the hungriest of cows."

Based at Bushey Lane Farm, Preston Bissett, Bucks, M A Richardson Agricultural Contractors harvests about 400ha (1000 acres) of maize in addition to 810ha (2000 acres) of grass silage each year. Over the last 18 years, Mr Richardson has learnt to understand the requirements of customers and crop alike, when it comes to harvesting maize.

"Maize is much harder to harvest than grass and its tougher on machinery too. Weve found the key to successful harvesting lies in chop length, corn cracking and ensiling. If you cant get these areas right, then you need to find someone who can do it for you," says Mr Richardson.

Mr Richardson uses a self-propelled Claas Jaguar 695 Mega, which in maize-trim is fitted with a Kemper Champion header.

"The header offers no benefit to the value of the crop, but it makes harvesting easier and quicker because you are not tied into the rows," he says. But from here on in, using Mr Richardsons Claas Jaguar as an example, its all change to harvest maize.

"Because the crop is drier, harder, bulkier and more abrasive than grass, tougher chopping parts need to be fitted. Maize demands plenty of horsepower, too.

"We start by removing all grass knives and the shear bar from the main chopping drum and replacing them with special maize knives with a harder shear bar. Theyre tougher blades than those used for grass and will withstand more frequent sharpening," he explains.

"Usually, we sharpen the blades every 1.5 hours on maize and were only harvesting about 50 acres a day. This compares to sharpening two or three times a day on grass, when we cover about 90 acres each day. I would expect output to drop by up to 50% with a poor operator who sharpens blades once a day." But output isnt the only thing that suffers, he adds.

"You have to keep everything razor sharp to get a cleanly cut, short chop length – typically about 4mm – which will help forage digestibility. Blunt blades and a short chop means a mushy pulp goes into the clamp." But to achieve the best digestibility, Mr Richardson says a corn cracker is essential.

"I wouldnt harvest maize without a cracker. Every grain must be split so cows can digest it."

Working like a mangle, the corn cracker uses two spring-loaded serrated profile steel rollers. These rollers turn at different speeds to squeeze and shear the crop as it passes between the rollers.

"At the start of the season, we set the rollers with about 3mm clearance between them. Moisture in the crop means the corn splits easily. As the season progresses and the crop toughens up, the roller settings need to be much tighter to ensure every grain is thoroughly split," he says.

"When the roller ribs start to wear down, its time to replace them to maintain their cracking ability."

Additionally, the heavier weight of maize requires small changes to the Jaguars blower paddles, to ensure the crop makes its journey to the trailer and doesnt block the discharge chute.

Confident that all correct adjustments have been made, a few yards of foraging allows the chopped crop to be inspected in the trailer.

"A visual inspection will soon tell you if the forager is set correctly – every piece of corn should be cracked or split, and the crop will be chopped into small, clean pieces."

But once the maize has left the forager, the job is far from over. Mr Richardson says clamping must not be overlooked at the expense of using a high-performance forager, which will clear fields in double-quick time.

"Rushing the clamp can undo the good work of a correctly set forager – weve found that maize needs ensiling in lots of thin layers, with constant rolling to get air out of the clamp," he says.

"I always visit my maize customers in the winter to discuss the next years crop – and if their silage isnt up to scratch then its me who suffers. So its important for me and my team to do the best possible job."


Kemper header for faster harvest.

Replace knives and shear bar.

Set corn crackers.


&#8226 Kemper header for faster harvest.

&#8226 Replace knives and shear bar.

&#8226 Set corn crackers.

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