Thursday, December 8, 2022

Holding On To Soil Moisture In The Southern Plains

SHELLEY HEINRICH SLATON, TEXAS
Shelley Heinrich
Slaton, Texas

Rainfall is critical to cotton across the Cotton Belt. However, effective ways to capture and maximize precipitation in the Southern Plains are always top of mind for the region’s producers. Cotton Incorporated and many cooperators invest in research to explore strategies for making the most of the limited rainfall in the area.

Conservation Tillage/Cover Crops

One West Texas study in Martin County analyzes water-efficiency data generated from using conservation tillage techniques and cover crops. This multi-institutional collaboration between the U.S. Department of Agriculture Cropping Systems Research Laboratory and Texas A&M AgriLife Extension, funded by Cotton Incorporated, was established in 2019 with five area growers.

The project focuses on how cover crops could be a viable tool for this area and how they could impact production, water use, fertility, wind erosion and economics. The study includes five fields, each with two large-scaled testing sites of cover crop, no-till and conventional tillage techniques.

Each field was equipped with soil moisture sensors to track water infiltration and usage by the crop. Infra-red plant canopy temperature sensors were used to track plant stress and crop responses to rainfall events. These sensors provided continuous information to researchers about each field’s soil and crop conditions.

With two years of the study complete, the data reflects an increase in water-use efficiency in the fields using conservation tillage techniques and cover crops. The roots of the cotton plants in conservation tillage plots extracted water two times deeper than those of conventional tillage plots.

Dr. Paxton Payton, a plant physiologist at the USDA Cropping Systems Research Laboratory in Lubbock, Texas, said, “During times of little rainfall, it is important to capture whatever moisture you receive and to reduce the amount of water runoff. This research shows that moisture falling on conservation tillage fields with a cover crop could penetrate the soil profile by an additional 20 mm and 25% more effectively than a conventionally tilled field.” 

Rainfall Timing Study

A different study, led by Dr. Natasja Van Gestel, assistant professor of biological sciences at Texas Tech University, looks at soil moisture content and strategies with respect to the timing of rain events. Twenty West Texas fields were tested for organic matter, soil moisture and nutrient levels in this study. Results showed that soil moisture and nutrients (N, P, and K) were more stable in fields with organic matter and conservation tillage. The study also discovered that areas with a high content of clay matter were able to retain more organic matter and soil moisture. 

Response to rainfall in conservation tillage cotton crop (red line) compared to conventionally tilled (no winter cover) cotton crop (blue line) in Martin County, Texas. The cover crop soil profile showed an approximately 25% greater water infiltration response to rain events compared to conventional tillage.

With respect to timing, the study identified cover crops and conservation tillage as ways for producers to take advantage of rainfall events when there is the uncertainty of future rainfall. Van Gestel reported, “Summer storms are often intense. Our research with cotton growers across West Texas showed improved August rainfall capture — a crucial time in the cotton-growing season — in fields with reduced tillage and residue.” 

Dr. Kater Hake, vice president of agricultural research for Cotton Incorporated, said, “The results regarding soil moisture absorption and retention in August, during the critical time of boll maturation, is encouraging. This research and information are vital to have in a region where every drop matters to producing a profitable cotton crop.” 

These two research projects, funded by Cotton Incorporated, show reduced tillage practices and cover crops can make a difference in effectively capturing rainfall. For more information on these and other cotton research projects in your area, visit Cotton Incorporated’s Cotton Cultivated research website at https://cottoncultivated.cottoninc.com. 


Shelley Heinrich is the Cotton Board Southern Plains regional communications manager. Email her at sheinrich@cottonboard.org.

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