Is your maize ready to be harvested?

Maize is an expensive crop to grow and has huge potential when placed in a pit for the winter, but the high-energy feed needs to be harvested at the appropriate time to get the most from the crop.

The key decider on cutting date is when the sugars have turned to starch. Sugar is not stable in the pit and if crops are cut with a high sugar content this sugar will be lost and run into the effluent tank and the high-energy value of the maize crop will be lost.

Maize crops with green leaves around the cob are not ready for harvest. If leaves have turned white beside the cob they should be ready to cut and sugar content will be down to approximately 1-2%.

Dry matter content should be around 30% at this stage and starch content should also be approximately 30%.

The Teagasc maize guide describes how the grain in the cob should be developed at harvest time.

This guide advises the farmer to take a cob, break it in half and discard the half that was attached to the plant.

From the remainder of the cob, take a kernel or grain and squeeze the kernel to see what level of milk is still present. Take a look at this chart (below) and use it as a guide in the field when deciding on the correct time to harvest your maize crop.

Image source: Teagasc

Once the top 75% of the kernel is hard the crop is almost ready to be harvested and the whole crop is at approximately 27% DM content.

Once the whole kernel is hard the crop needs to be harvested immediately and the whole crop is at approximately 33% DM content.

Early-maturing varieties

Ambition is classified as an early-maturing variety on the Department of Agriculture’s recommended list for 2020. It has a rating of 116 for earliness of maturity. To put this into perspective, medium-maturing varieties have a rating of 98.

Spyci CS and SY Feeditop are classified as early-medium maturing varieties with ratings of 104 for earliness of maturity.

Konfluens, LG30211, LG31.235, P8200 and P8201 are all rated as medium for earliness of maturity, while just one variety, P7932, is described as medium-late for earliness of maturity.