Back to December 2017

Improving Soil Health Through Cover Crops for Pecans

The Noble Research Institute conducts studies to help growers better their soil health, and ultimately, their pecan production.


Rohla encourages you to dig in your soil and get your hands dirty. Take a look at what’s in the soil and the structure and texture of the soil, then compare that to other areas where you think there is good soil. (Photo by Jeff Goodwin, Noble Research Institute)

Recently, there has been a lot of attention centered on soil health.  While the importance of soil health is not new to pecan producers, I believe this is an area where we as producers can definitely make improvements.

As I travel and see different operations and visit with managers about their management practices one thing that is often not addressed is soil health. The truth is improving soil health will benefit your operation over time.  In order to begin addressing these types of issues, the Choctaw Nation of Oklahoma’s (CNO) Department of Agriculture has partnered with the Noble Research Institute to conduct research on two irrigated pecan orchards.

The CNO has recently planted a new orchard of 1,200 trees near the Red River in Garvin, Oklahoma and the Noble Research Institute has a young, producing orchard in Ardmore, Oklahoma in which the cover crop treatments will be replicated to provide reliable data collection.

Four cover crops will be planted on the orchard floors and a Bermuda grass treatment will act as the control to compare outcomes. This project will provide a comprehensive analysis of each cover crop and how they affect moisture retention in irrigated pecan orchards, soil health, nutrient uptake, and tree trunk and shoot growth.

At the Choctaw Nation’s new pecan orchard in Garvin, Oklahoma, soil monitors like the one pictured here are used to measure soil moisture levels and to gather data for the cover crops study. (Photo by Catherine Clark)

The objectives of the study are to 1) determine which cover crop improves the overall soil health of the pecan orchards, thus lowering the need for synthetic inputs; 2) compare soil moisture measurements to determine which cover crop offers the least amount of competition for orchard floor water and 3) ascertain which cover crop provides the greatest overall tree growth and pecan production (at the Ardmore orchard) through nutrient uptake.

With the cost of inputs and importance of soil health in pecan groves, I believe the objectives of this study are right on target. Any management practice that could potentially offset these costs is beneficial.  For example, in this study, we will use clover as one of the cover crop treatments. Research has indicated that clover can improve nitrogen in the soil.  This, in turn, could reduce the amount of additional fertilizer needed in the grove.

Cover crops also help deter erosion, increase soil moisture and provide a more stable footing during harvest. Obviously, we want our orchards to have healthy trees with high production rates. If we can determine a correlation between cover crops and nutrient uptake, producers could modify current practices potentially increasing production rates. Soil health is important to the livelihood of pecan producers and should be a primary focus for producers. Along with this study, we will be implementing similar studies within our older dryland orchards and in the native bottom to evaluate soil health and the ways to increase it.

Author Photo

Charles Rohla

Rohla is Manager of the Center of Pecan and Specialty Agriculture at the Noble Research Institute, Ardmore, Oklahoma. ctrohla@noble.org

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