9 Reasons Disc Harrow Not Cutting Deep Enough

disc harrow not cutting deep enough
disc harrow not cutting deep enough

Disc harrows are commonly used farming equipment that is designed with rows of concave metal discs that are used for cutting. The row is designed to tilt the soil where crops or seeds need to be cut off or planted, respectively.

In addition, it can help get rid of unwanted plants and weeds as well. The disc harrowing process is completed before and after plowing and has the capacity to cut around eight-inch deeper into the soil.

This is because a disc harrow has highly balanced and sturdy discs, which makes them reliable equipment for soil preparation and provocation of the weed. However, the disc harrows tend to stop working at times or the disc harrow stops cutting deep enough but there are solutions to this cutting issue.

Why Is My Disc Harrow Not Cutting Deep Enough?

  1. Weights Matter

Weights Matter

Before you start using the disc harrow, you need to understand that weight plays an essential role. The harrow’s weight depends on the number of blades and volume of discs. If you want to cut deeper into the soil, the discs and blades need to be heavier.

It is recommended that you conduct a patch test to see how deep it’s cutting. So, if the disc harrow is not cutting deep enough, you need to replace the discs, blades, or both to opt for heavyweight components.

  1. Adjusting Your Blade Angle

Adjusting Your Blade Angle

The angle at which the disc harrow’s blade is cutting also impacts the cutting capacity of the equipment. For instance, cutting deeper demands a sharp angle as it helps increase the penetration of the blade.

On the contrary, a shallow angle can decrease the penetration capacity of the blade and disc. So, you need to adjust the blade angle. Also, while adjusting the angle, you should keep testing after small adjustments to find the best angle.

In addition to cutting deeper, a sharp angle makes sure that the discs are attacking the soil with more force and creates a bigger furrow. Moreover, it can turn over more soil, resulting in soil pulverization.

While you are adjusting the blade angle, make sure that the rear discs have a proper angle to cover the furrows left behind by the front side discs. As a result, the cutting will be smooth.

Secondly, you need to remember that the disc can add residues into the soil almost as deep as the cutting depth’s 50%. For breaking the dirt molds, keep in mind that the second disc pass must not be on the same angle as the first disc pass.

For this reason, it’s recommended that you enter the patch at a 30-degree to 90-degree off the angle of the first disc pass. This is because it helps reduce the number of streaks in the residues, promising a better soil finish.

  1. Speed of Cutting

Speed of Cutting

Operating the disc harrow at the right speed is extremely important. This is because if you go too slow or fast, you won’t be able to achieve the desired depth of the soil.

It is recommended to achieve a cutting speed of four miles to six miles an hour. However, the speed depends on the overall condition of the soil. For instance, the disc harrow can achieve eight miles in an hour if the soil is sandier.

On the contrary, if you aren’t certain about which speed is suitable for the soil, it’s recommended to conduct some test drives and measure the furrow’s depth to find the right speed.

  1. Condition of Soil

Condition of Soil

Cutting through soil is a difficult process and the disc harrows have to work hard to make cuts. However, if the soil is sandier, the blades will cut in too deeply.

On the other hand, if the soil is hard, the disc harrow will fail to get a deeper cut. So, if your disc harrow isn’t making deep cuts, it’s recommended that you soften up the soil a bit.

Heavy harrowing or smudging are the most common methods of reducing the roughness and hardness of the soil. This is because this method can break off the soil mounds, making it easier for the discs to pass through.

For this purpose, you have to purchase posture, diamond, or chain harrows as they help level the soil. Also, smudging should be done in the spring season because the soil is dry enough to cater to the shattering of the mounts.

  1. Blade Diameter

Blade Diameter

When you set the tillage depth of the disc, you need to be careful about the blade diameter because it can directly influence the cutting capacity. If the soil has a normal condition, the ideal cutting depth should be 25% of the harrow’s blade diameter.

For instance, if you are using the 32-inch blade, it should make eight-inch deep cuts. So, it’s recommended that you calculate the suitable tillage depth and set the disc to that depth with the help of depth controls.

  1. Weight Per Blade

Weight Per Blade

It’s tempting to start cutting the soil after adjusting the tillage depth but you need to be careful about the weight a blade is carrying. Keep in mind that more load on the blade results in a deeper cut, irrespective of the diameter.

You can calculate the weight per blade by dividing the disc’s load by the total number of blades on the disc harrow. In addition, you need to conduct a short test to measure the furrow’s depth.

In case the furrow is deeper than the blade diameter’s one-quarter, it means that the blade has too much weight. On the other hand, if the furrow is shallow, you have to increase the load or pressure on the blade to increase the cutting depth.

  1. Tire Pressure & Crossbar

Tire Pressure & Crossbar

When you pull through the disc harrow behind a tractor and see that the cuts aren’t deep, you have to check the tire pressure. The disc harrows are basically pull-behind equipment that has wheels for moving.

So, if the wheel is less inflated or has uneven pressure, the cutting will be adversely impacted; the cutting won’t be deep enough and the furrows will be uneven.

Secondly, the disc harrows are designed with a crossbar that connects the three-point hitch to the main body of the harrow.

With regular use, the crossbar bends, and as a result, the harrow won’t be able to pull through, resulting in shallow cutting. The solution is to call the mechanic to get the crossbar straightened. However, you can also get the crossbar replaced.

  1. Discs


The disc harrow’s discs are designed in a way that the soil rides upon them and is deposited back on the group in an even form. However, there are times when discs hit the rock in a field, which bends it.

As a result, the rows will be uneven and the cutting depth will be reduced. If the disc is bent, you have to get them replaced.

In addition to checking the bending, you need to ensure that the discs’ nuts are fully tightened up. In case the discs are loose, they won’t be able to penetrate sturdily into the soil, hence the depth issues. So, just use a socket wrench for tightening up the disc.

  1. Bearings In The Disc

Bearings In The Disc

The bearings are used to ensure the tight connection of the disc on the harrow’s frame. If you’ve been using the disc harrow during summer and hot spring, there are chances that the soil has clogged the bearings.

In addition, the bearings can dry out with regular exposure to dust and dirt. For this reason, you should inspect the bearings, and if they are dried out, use some grease to lubricate them.

The Bottom Line

A disc harrow is great equipment for farmers when they need to cut out the weeds and make furrows for planting new seeds. However, if they stop cutting deep enough, you can try out these solutions. As a preventive measure, you should always check the disc’s level and angle before you start cutting the soil.

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