But they are hard to find in the drier soils of eastern Colorado where water and organic matter is limited. Adding earthworms to fields where they are not currently found could help enhance the health and productivity of the soil. In areas where droughts are common, though, can earthworms survive? A new study suggests that they can.
This is an earthworm in estivation.
Credit: Photo courtesy of Jacob McDaniel
Earthworms use water for many things – for respiration, to keep their bodies from drying out, and to make the mucus that helps them slide through the soil. When soils get dry, earthworms go into estivation.
"During estivation, earthworms wrap their bodies into a tight knot to reduce the amount of surface area exposed to the soil," explains Jacob McDaniel, lead author of the study published today in the September-October issue of Soil Science Society of America Journal. "Then they'll seal themselves up in a chamber lined with their mucus. Inside that chamber, the humidity is higher so they don't dry out as the soil dries."
The ability of earthworms to go into estivation suggests they can survive dry periods in the soil. The aim of the current study was to find out how long they could survive and whether they would recover after an extended drought. To answer those questions, researchers from Colorado State University recreated drought conditions in pots containing soil and worms.
Earthworms live in Colorado soils, but their distribution is limited. They are mostly found in areas close to water or with higher levels of precipitation or irrigation. Earthworms for the current study were gathered near an irrigated alfalfa field close to Fort Collins. If these worms can survive periods of drought, they could be established in no-till, dryland agricultural soils of eastern Colorado to improve and mix soils.
Four different levels of drought stress were created for the study: constant water and one, two, or three weeks without added water. These conditions were based on rainfall patterns in the area where the soil for the study – a sandy loam from a dryland agricultural field – was collected.
Before the start of the study, the earthworms were gathered, allowed to acclimate to the soil for four days, and weighed. Each pot containing the soil and earthworms was then watered. Pots were again watered at the end of each one-, two-, or three-week drought period. At 21, 42, and 63 days, the earthworms were found within the soil and classified as active, in estivation, or dead. The alive and estivating earthworms were then rewetted and weighed.
McDaniel and his co-authors found that the length of drought stress affected the number of earthworms that died or went into estivation. More earthworms went into estivation as the drought stress period got longer. Fourteen percent of earthworms died in the three-week drought, significantly more than in the other treatments. Still, the earthworms that survived drought, even for three weeks, were able to recover after rewetting.
"If the soil did get rewetted, their weight didn't change," says McDaniel. "They should be able to survive through and recover after a drought that matches our conditions."
The results of the study suggest that by going into estivation, earthworms could survive in drought-prone soils, such as those in eastern Colorado. But further work will be done to pinpoint strategies to increase their survival and understand their drought response. McDaniel explains that an important step will be to see what happens out in a field.
"The stress in the pots could be very different than what we would see in the field," he says. "Future work needs to be done in the field setting with actual droughts instead of set time periods."
Also, researchers want to find out whether the amount of time earthworms are allowed to acclimate to soils before encountering drought stress affects their survival. If an ideal length of time for acclimation can be found, efforts to establish earthworms may be more successful. Then even drought-prone, dryland soils could reap the benefits that worms provide to other soils throughout the world.
For more information, contact Jacob McDaniel at firstname.lastname@example.org.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://dx.doi.org/doi:10.2136/sssaj2013.02.0064.
Soil Science Society of America Journal, http://www.soils.org/publications/sssaj, is a peer-reviewed international journal published six times a year by the Soil Science Society of America. Its contents focus on research relating to physics; chemistry; biology and biochemistry; fertility and plant nutrition; genesis, morphology, and classification; water management and conservation; forest, range, and wildland soils; nutrient management and soil and plant analysis; mineralogy; and wetland soils.
The Soil Science Society of America (SSSA) is a progressive, international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.
SSSA supports its members by providing quality research-based publications, educational programs, certifications, and science policy initiatives via a Washington, DC, office. Founded in 1936, SSSA proudly celebrated its 75th Anniversary in 2011. For more information, visit http://www.soils.org or follow @SSSA_soils on Twitter.
Jacob McDaniel | EurekAlert!
Researchers invent tiny, light-powered wires to modulate brain's electrical signals
21.02.2018 | University of Chicago
The “Holy Grail” of peptide chemistry: Making peptide active agents available orally
21.02.2018 | Technische Universität München
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
21.02.2018 | Life Sciences
21.02.2018 | Life Sciences
21.02.2018 | Materials Sciences