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 email@example.com.
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!
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy