It’s harvest time. You’re busy making sure the crops get taken off, the grain cart keeps moving, and the semi running. There are a lot of moving parts, people, and profits. Possibly the last thing you’re thinking about is compaction. But with heavy and frequent equipment tracking up the field, the soil is most vulnerable to compaction during harvest. 

Compaction is the silent thief of yield. While it’s hard to see the immediate effects of soil compaction, its impact is severe and long-lasting. Research shows that yield loss from a single compaction event can persist for over a decade. While natural freeze/thaw cycles and tillage practices can counteract some of the effects, they often won’t entirely fix deep compaction either. 

Let’s dive into the main factors contributing to soil compaction during harvest and how to minimize them:

Problem: Heavy Equipment

The first factor to consider is the inherent weight of harvest equipment. From combines to grain carts capable of holding over a thousand bushels, heavy axle loads put significant pressure on the soil.

Solution: Reduce Axle Load and Monitor Tire Pressure

Although easier said than done, efforts to reduce axle load can be extremely beneficial. When purchasing a new combine, keep weight in mind. Consider opting for lighter equipment like the Gleaner T Series combine, which is 24% lighter than comparable models, for the reduced soil impact but also for efficiency and fuel savings.

To further protect the soil, try not to fill grain carts to their maximum capacity. But let’s be honest, efficiency is king, and the capacity of newer combines usually keeps the grain cart full. Therefore, the best advice is to implement controlled traffic by establishing a designated path back to the semi and using existing paths. More on controlled traffic later. 

Additionally, check your tire pressure. See the manufacturer’s guidelines regarding the lowest allowable pressure to still safely carry the heaviest load. A tire with lower pressure expands its footprint and can reduce surface compaction, whereas an over-inflated tire has a smaller footprint causing more compaction.  

Problem: Equipment Traffic

The nature of harvest equipment means a large amount of the field is also subject to tire trafficking. Unlike sprayers and planters with wide working widths, a combine with a 12-row corn head, for instance, will still pass over every 30 feet across the field. It's not out of the question to assume over 30% of the field is tracked up just during harvest—probably more in most situations. 

Solution: Controlled Traffic and Designated Unloading Zones

Control the traffic patterns used by tractors and grain carts by sticking to specified lanes in the field. Since 80% percent of compaction happens during the first pass, using the same paths for machinery can help prevent further compaction in other areas of the field. 

Whenever possible, unload grain carts in the headlands, especially when they are fully loaded. This limits compaction to specific areas rather than spreading it across the entire field. 

Lastly, avoid driving semi trucks and trailers across the field. Their narrow tires and high pressure, usually carrying a significant amount of weight, increase the risk of compaction.

Problem: Soil Conditions 

Harvest season often coincides with wetter conditions, heightening the risk of compaction. Water amid soil particles acts as a lubricant, allowing them to compress more easily. The economic cost of soil compaction during a wet harvest can be substantial. In 2019, researchers estimated a $587 million loss due to compaction in the Midwest during wet conditions. The challenge is balancing wet harvest conditions with the timeliness of harvesting crops. 

Solution: Avoid Working in Wet Fields

The most straightforward way to reduce compaction is to avoid rushing into fieldwork during overly wet conditions whenever possible. Moist soil is especially vulnerable to compaction, so waiting for drier conditions can make a significant difference.

Minimizing soil compaction during harvest is important for maintaining soil health and optimizing crop yields. By implementing these practices, you can reduce the long-term impacts of soil compaction on your fields. For more farming insights, check out other topics on the Acres of Insight blog series.