In Press: PSS’s Slaughter finds manure improves soil and microbe community
By: Norman Martin
Recently, Lindsey Slaughter, an assistant professor of soil microbial ecology/biochemistry in Texas Tech's Department of Plant and Soil Science, was featured in a new article written by Kaine Korzekwa for the Crop Science Society of America website. Here's part of the conversation.
In the dry air and soil of the Texas High Plains, improving soil health can be tough. Many people usually think of healthy soil as moist and loose with lots of organic matter, but this can be hard to achieve in this arid area of Texas.
Lindsey Slaughter, an assistant professor in Texas Tech's Department of Plant and Soil Science, and a Lubbock-based researcher team that included her graduate student Rael Otuya, along with former PSS Thornton Distinguished Chair Charles West, PSS assistant professor of soil physics Sanjit Deb and Veronica Acosta-Martinez, a soil scientist and microbiologist with the USDA-ARS Cropping Systems Research Lab in Lubbock, set out to test a solution that killed two birds with one stone.
They put excess cow manure on these soils to see if they could make them healthier. The project was funded by the Southern Sustainable Agriculture Research and Education and the USDA's National Institute of Food and Agriculture. Results were recently published in the Soil Science Society of America Journal.
"We know that planting perennial grasslands for cattle production can help protect and restore soil in semi-arid lands that are likely to erode and degrade from intense farming, but producers need additional ways to increase soil carbon and nutrient stores," Slaughter said. She described soil health as the ability of a living soil ecosystem to perform a variety of important functions. These include cycling nutrients, storing and purifying water, helping plants and animals, and more.
The "living" part is made up of various microorganisms that help a soil be healthy. They, for example, help break down materials like manure so that it and its nutrients become part of the soil. "Improving the soil's ability to perform these roles and support plant and animal life is our target for soil health," Slaughter said. "Adding the manure can provide a boost of material that can be incorporated into soil organic matter. This helps provide a stronger foundation for more microbial activity and nutrient cycling."
This is why in their study the team applied a low one-time amount of manure to two types of pastures to look into this. The pastures they put the manure on had either grass only that was fertilized occasionally or were a mix of grass and legumes that was not fertilized. Manure helps, but results take time. Overall, the researchers did find that manure helped increase soil organic carbon and the number of microbes in the soil. These are two important characteristics of a healthy soil.
Slaughter noted that it took almost a year and a half to see these changes, although this was not totally surprising. "This tells us that it can take a long time for even a little added compost to become incorporated into the soil organic matter of semi-arid grasslands, but it definitely helps," she said. "We think this is mostly due to the dry climate at our study site. We commonly get little rainfall per year. The microbial community was not able to work quickly or efficiently to decompose the manure without water."
Results also showed that the pastures receiving fertilizer responded better to the manure. This is likely because the nitrogen in the fertilizer helped the microbes decompose the manure better. "Microbes help directly with releasing nutrients from organic material in a form that plants can use, as well as decomposing those residues to build soil organic matter," she said. "A lot of work has been done on how this can help improve cropping systems. However, we wanted to also test this on forage pastures."
Looking ahead, Slaughter said that the next steps in this work includes whether more manure or multiple applications would get faster results. In addition, the researchers hope to investigate if irrigation or different types of fertilizer would help incorporate the manure faster.
Contributing Kaine Korzekwa
CONTACT: Lindsey Slaughter, Assistant Professor of Soil Microbial Ecology/Biochemistry, Department of Plant and Soil Science, College of Agricultural Sciences and Natural Resources, Texas Tech University at (806) 834-1345 or firstname.lastname@example.org
0401NM21 / PHOTOS: Paul Green (top) and Phil Brown (bottom)
Editor's Note: For the full text of Kaine Korzekwa's story on the Crop Science Society of America website, please click here
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Editor: Norman Martin
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