Lately it seems that those of us in the soils and crops discipline have received more questions about land application of drilling mud or "mud farming."
Let's discuss what drilling mud is and what it can contain. The average drilling mud or fluid may consist of bentonite clay carried in water, diesel, mineral oil or "coal" with barium sulfate thrown in to increase the density and help remove the rock particles from the well. Note that drilling fluids will vary from well to well depending on the depth of the hole and type of rock formation that they are drilling through. When they are through with the drilling mud, drillers can dispose of it by taking it to either a landfill or by land application.
Land application is where the drilling fluids are spread over the top of pasture or farmland. The rate will depend on the soil type and the make-up of the drilling mud. What is actually occurring is that the drilling mud is being diluted or allowed to break down when spread over the property.
Some of the cons to applying drilling mud are that it can add salts and/or heavy metals to the soil, you may be adding clay to clay soils and applications over 3 inches thick can kill your grass pastures. Water run-off from the property can create additional environmental concerns.
Given the possible problems listed above, I personally would not apply drilling mud to any property of mine. However, each property owner needs to make his or her own decision and there can be good reasons for the practice. In addition to the financial incentive you receive, your soil water-holding capacity can be increased, you can improve your soil texture (if you have sandy soil), and there is the possibility of improving your bermudagrass stand by tilling the drilling mud. The question you need to ask yourself is, "Does the economic benefit exceed the risk of application?"
If you apply drilling mud to your pastures or farmland, it is important to incorporate the mud 6 inches deep in the soil. With the application of 3 inches of mud, you are looking for an implement that can till the soil 9 inches deep!
Before you have drilling mud applied to your property, you need to have multiple, specific tests run on your soils and on the composition of the drilling mud. This involves having the materials analyzed as a saturated paste extract and determining if heavy metals are present. Then you will need a qualified professional determining the amount that can be safely applied to your property and if any other soil amendments will be required.
I cannot express enough the importance of developing a formal (lawyer-approved) contract with the company and include a clause to allow for the repair of roads, gates, fencing, cattle guards, low water crossings, etc., that may be damaged by the heavy equipment used for application. Also include any requirements for revegetating and fertilizer needed to bring the land back into production as well as future analysis of the pasture or farmland. Take time to educate yourself since each state has different regulations covering the application of drilling mud and fluids.