Forestry, Wildlife and Natural Resource Management > FWNRM Blog > Posts > Hardpan May Be the Culprit for Your Failing Wildlife Food Plots

Most properties managed for wildlife have at least a few food plots that get planted on an annual basis. The for​mula for successful wildlife plots generally involves: testing soils, liming and fertilizing as appropriate, managing weeds, tilling, planting, and leaving the rest up to Mother Nature. However, despite following this recipe, you may have noticed that some or all of your plots are not producing like they used to or that they seem to be prone to failure in the summer months. The scenario might go something like this:

Your food plot looks like it is on its way to serving as a wildlife buffet until late July and August rolls around and then things take a turn for the worse. The once up-and-coming plot suddenly stops growing and perhaps even fails completely and it’s off to plan B… again, for perhaps the 3rd, 4th, or 5th season in a row. You send off soil samples to the university for testing and the results come back stating that that the soils are properly limed and fertilized and you are left scratching your head.

There may be one factor that you hadn’t taken into account…hardpan.


Hardpan is essentially a layer of soil that has become dense and compacted over years of heavy equipment riding overhead, such as lime trucks, tractors, spray rigs, etc. Tilling and disking a field also helps to create hardpan as this allows fine clay particles to continually settle out and collect just below the depth of disking. This hardpan layer can be thought of as a concrete pad from 2”-10” underneath the topsoil that roots cannot penetrate and that water cannot drain through. Hardpan restricts root development, reduces the ability of soils to retain moisture in the long term, and creates a field that is prone to flooding because moisture cannot pass through the nearly impermeable hardpan layer.   


In just 3 years time a hardpan layer can develop just several inches beneath the topsoil. When this occurs a crop will grow well up to July until roots reach the hardpan and cannot grow any deeper. As the July and August heat comes and precipitation decreases, the plants will appear to suffer from drought like conditions even if Mother Nature grants us with the conditions normally necessary to maintain healthy wildlife plantings. Additionally, even minor rains can drown out plantings because the hardpan creates ponding and greatly increase the time a field takes to drain.


Testing for hardpan is not difficult and can be achieved by inserting a soil probe or metal rod directly into the soils (soil probes may be borrowed from your local extension office, but please call ahead for availability). The probe/rod should insert fairly easily through uncompact top soils. If hardpan is present, it will be very noticeable as it creates a great deal of resistance and the probe will require much more force to insert.   Continue pushing through the hard pan until you feel the resistance decrease. STOP and mark the depth at which you felt the probe break through to less resistance as this is the bottom of the hardpan. This depth reading is important to know if you want to be successful at eliminating hardpan.


Eliminating hard pan requires the use of a subsoiling chisel plow and a tractor of at least 50 horsepower, both of which can be rented. The plow should be set to the depth that you measured the hardpan with your soil probe.  Do not set the plow deeper as this will only serve as a waste of fuel and provide no further benefit. This will ensure that the hardpan is sufficiently broken, it is best to plow the entire field one-way (lengthwise) and then go over it another time in the opposite direction (widthwise).


Hardpan is an issue that is often overlooked and may just be the cause of crop failure if gone unchecked for a few years. Understanding hardpan is just one more tool to keep in your planting arsenal. The next time you recognize a failing food plot, or if you have not subsoil plowed your fields in the last three years, test to see if a hardpan has developed, in the long run, it may save you money, time, and headache.


Information like this and so much more is available at your counties Alabama Cooperative Extension System office. Please give us a call or make a visit!

Norm Haley

Regional Extension Agent I – Forestry, Wildlife, & Natural Resources

Alabama Cooperative Extension System

500 Grand Ave. SW, Suite 300

Fort Payne, AL 35967


Office: 256-845-8595

Cell:    256-630-4248

Fax:    256-845-8596




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