Preparing for the maize silage harvest

Many Waipa maize silage crops are running two to three weeks late this season due to the combination of later planting and a very cool early summer.

As there is considerable variation between, and even within crops, it will be important to keep an eye on plant maturity to ensure your maize silage comes off at the right time to maximise yield and quality.

Best-practice maize silage harvest guidelines are as follows:

• Harvest when the maize drymatter is between 30-38 per cent. Harvesting too early will result in a lower yield and a higher risk of fermentation losses. Typically crops which are less than 38 per cent drymatter are more difficult to compact resulting in a slower fermentation and greater losses when the stack is exposed to the air at feed-out time. If you are getting short of feed, consider other supplementary feed options before harvesting your maize crop too early.

• Always use a quality silage inoculant. Silage inoculants fall into two general categories - those which improve fermentation resulting in lower losses in the stack (e.g. Pioneer brand 1132 or 1174), and those which reduce heating resulting in lower losses (e.g. Pioneer brand 11C33) when the stack is exposed to the air at feed-out time. Independent research has shown that using a quality inoculant like Pioneer brand 1132 can give you a return of more than $8 per $1 invested even when fermentation conditions are good*. But be careful when deciding which inoculant to apply. New Zealand research has confirmed overseas data which shows there are significant differences in the performance of silage inoculants^. Some products deliver significant fermentation benefits and reduce heating. Others don't work. Always ask to see trial data and check there are guaranteed bacteria levels on the product label.

• Ensure the kernel processor is set so that 99 per cent (target minimum 80 per cent) of the kernels are broken into at least four pieces. This will ensure animals can get access to the high energy starch which is within the maize kernel.

• Spread the maize in thin layers and compact it well. Compaction is a function of vehicle weight, rolling time and the depth of the layers of chopped maize that is being compacted. Thin (100-150 mm) layers compact to a higher density than thick layers.

• Seal the stack or bunker completely. Compaction removes air from the forage and sealing keeps it out. Ideally the stack should be covered and sealed immediately after harvest as this will speed the fermentation process and reduce losses. Tape holes and joins and weight the cover down using tyres that are touching, sand bags or lime. Sand or limestone should be used to seal around the edges of the bunker or stack.

• Control rats and mice. Keep the stack area free of weeds that can provide cover for rats. Place rat baits in bait stations around the stack or use electronic traps to ensure vermin are controlled throughout the storage and feed-out phase.

Don't compromise maize silage quality at harvest-time. Make sure you get the best possible result by following best practice harvesting and storage guidelines.

* Returns calculated using drymatter recovery from Pioneer trails and milk production measured in a Washington State University dairy trial that compared Pioneer brand 1132 inoculated maize silage with an untreated control. Assumes a milksolids payout of $6/kgMS.

^ Kleinmans et al, 2011. Using silage inoculants to improve the quality of pasture and maize silage in New Zealand. Proceedings of the New Zealand Grassland Association 73:75-80.