What Happens When Grain Gets Mechanically Damaged During Harvest?

Harvest is a busy time. There are combines moving, trucks coming and going, grain being transferred, and bins filling up quickly. Through all of that movement, grain goes through a lot before it reaches the bin. And sometimes, that handling can leave its mark. Broken kernels, cracks, exposed germs, splits, and other physical damage can happen during combining and as grain moves through augers, conveyors, trucks, and other equipment. This is known as mechanical damage, and depending on the crop and severity, it can affect more than just how the grain looks. 

What Causes Mechanical Damage? 

Every time grain is moved, there is another opportunity for kernels to be damaged.. The combine is one of the first places to look. Threshing that is too aggressive can crack or break kernels, while crop moisture and harvest conditions can also influence how susceptible kernels are to damage. Augers, conveyors, high drop heights, and repeated handling can all contribute.  

The result can look different depending on the crop. You may see broken or cracked kernels, damaged seed coats, splits, exposed germs, or an increase in fines. 

Why Does a Little Damage Matter? 

A cracked kernel might seem insignificant on its own. Across an entire bin, however, mechanical damage can have a larger impact. One of the immediate considerations is the amount of broken material and fines entering storage. Fines can concentrate in pockets within a bin, restrict airflow, and are more susceptible to mould and insect activity.  

Damaged kernels themselves can also be more vulnerable during storage. Research and extension guidance have shown that mechanically damaged grain can be more susceptible to mould growth and may have a shorter allowable storage life than sound grain. That makes mechanical damage worth paying attention to, especially when grain will be stored for an extended period. 

It Can Affect Different Crops Differently 

Mechanical damage is not necessarily treated the same way across every grain type. In wheat, for example, the Canadian Grain Commission defines broken kernels as pieces that are less than three quarters of a whole kernel. Shrunken and broken kernels are assessed as part of the grading process. (Canadian Grain Commission⁠). Mechanical handling can also result in degermed wheat kernels, where the germ has been removed. Depending on the wheat class, this can have grading implications. (Canadian Grain Commission⁠) 

For malting barley, maintaining the physical integrity of the kernel is particularly important. Skinned and broken kernels can negatively affect germination and the malting process, and rough handling or poor threshing are common causes. (University of Minnesota Extension⁠) The important point is that mechanical damage is not just cosmetic. What the damage means depends on the crop, the type of damage, and the intended end use. 

Harvest Conditions Matter Too 

There is no single combine setting that works for every field, crop, or day of harvest. Kernel moisture, crop maturity, field conditions, crop type, and equipment setup can all change how grain moves through the combine and how easily it is damaged.That is why harvest adjustments are often a balancing act. The goal is to thresh and clean the crop effectively while limiting unnecessary kernel damage. And conditions can change throughout the day. A setting that worked well in one field or earlier in the afternoon may not produce the same result later. Checking the grain coming off the combine gives you another piece of information to work with. 

Take a Look at What Is Coming Off the Field 

During harvest, we spend a lot of time looking forward: the next field, the next truck, the weather forecast, and how much is left to get in the bin. It is also worth looking at the grain itself. Are you seeing more broken kernels than expected? Has the amount of fines changed? Are you noticing damage that was not present earlier in the day? 

Regularly checking grain quality can help identify changes while harvest is still underway. That information can help you decide whether equipment settings need another look or whether certain grain may need additional attention as it moves into storage.  

At Ground Truth Ag, this is one of the reasons we are interested in bringing more grain quality information closer to where decisions are being made. The earlier you understand what is coming off the field, the more information you have when deciding what happens to that grain next. Mechanical damage may only be one part of the grain quality picture, but during harvest, it is a part worth watching.