To meet the challenge of feeding a growing world population with minimal environmental impact, we need comprehensive and quantitative knowledge of ecological factors affecting crop production. Earthworms are among the most important soil dwelling invertebrates. Their activity affects both biotic and abiotic soil properties, in turn affecting plant growth. Yet, studies on the effect of earthworm presence on crop yields have not been quantitatively synthesized. Here we show, using meta-analysis, that on average earthworm presence in agroecosystems leads to a 25% increase in crop yield and a 23% increase in aboveground biomass. The magnitude of these effects depends on presence of crop residue, earthworm density and type and rate of fertilization. The positive effects of earthworms become larger when more residue is returned to the soil, but disappear when soil nitrogen availability is high. This suggests that earthworms stimulate plant growth predominantly through releasing nitrogen locked away in residue and soil organic matter. Our results therefore imply that earthworms are of crucial importance to decrease the yield gap of farmers who can’t -or won’t- use nitrogen fertilizer.
Continue reading “Earthworms Increase Plant Production”
Found this book on soil biology which highlights the importance of this soil food web. Excellent microscopy photos here, well worth checking over if you’ve never seen them before or if your thinking about looking at soil under a microscope. It also covers several other things like Seasonal Microbial Activity, Typical Numbers of Soil Organisms in Healthy Ecosystems, Methods for Measuring the Food Web etc. I loved reading this, I’m sure anyone who’s interesting in anything plant/soil related would too.
DIRECT DOWNLOAD: https://planetpermaculture.files.wordpress.com/2015/04/soil-biology.pdf
Laboratory tests were conducted to compare the effects of various concentrations of glyphosate and 2,4-D on earthworms (Eisenia foetida) cultured in Argissol during 56 days of incubation. The effects on earthworm growth, survival, and reproduction rates were verified for different exposure times. Earthworms kept in glyphosate-treated soil were classified as alive in all evaluations, but showed gradual and significant reduction in mean weight (50%) at all test concentrations. For 2,4-D, 100% mortality was observed in soil treated with 500 and 1,000 mg/kg. At 14 days, 30%-40% mortality levels were observed in all other concentrations. No cocoons or juveniles were found in soil treated with either herbicide. Glyphosate and 2,4-D demonstrated severe effects on the development and reproduction of Eisenia foetida in laboratory tests in the range of test concentrations.
Herbicides containing glyphosate are widely used in agriculture and private gardens, however, surprisingly little is known on potential side effects on non-target soil organisms. In a greenhouse experiment with white clover we investigated, to what extent a globally-used glyphosate herbicide affects interactions between essential soil organisms such as earthworms and arbuscular mycorrhizal fungi (AMF). We found that herbicides significantly decreased root mycorrhization, soil AMF spore biomass, vesicles and propagules. Herbicide application and earthworms increased soil hyphal biomass and tended to reduce soil water infiltration after a simulated heavy rainfall. Herbicide application in interaction with AMF led to slightly heavier but less active earthworms. Leaching of glyphosate after a simulated rainfall was substantial and altered by earthworms and AMF. These sizeable changes provide impetus for more general attention to side-effects of glyphosate-based herbicides on key soil organisms and their associated ecosystem services.
DIRECT DOWNLOAD: https://planetpermaculture.files.wordpress.com/2015/03/srep05634.pdf
Pesticides’ sublethal effects are not regularly taken into account when assessing agrochemical’s toxicity. With the objective of detecting chronic, sublethal effects of the widely used herbicide glyphosate, an experiment was performed using the earthworm Eisenia fetida as model organism. Earthworm adults were randomly assigned to three glyphosate treatments: control (no glyphosate), regular dose for perennial weeds, and double dose. Six E. fetida individuals were placed in each pot. Two random pots were taken weekly from each treatment and the number of adults, individual weight, number of cocoons, and presence and number of young earthworms were recorded. A matrix analysis was performed with the data. The matrix population model built showed that while the control population had a positive growth rate, both glyphosate treatments showed negative growth rates. The results suggest that under these sublethal effects, non-target populations are at risk of local extinction, underscoring the importance of this type of studies in agrochemical environmental risk assessment.
Non-target organisms can be at risk of local extinction due to agrochemicals chronic sublethal effects, which are not consistently taken into account in toxicity and risk assessment studies.
LOOK INSIDE (first 2 pages): http://link.springer.com/article/10.1007%2Fs11270-014-2207-3/lookinside/000.png & http://link.springer.com/article/10.1007%2Fs11270-014-2207-3/lookinside/001.png
“Bacteria, fungi, protozoa, nematodes, earthworms, and what lies between—a healthy ecosystem underfoot is key to the vigor of life above ground. A leader in soil microbiology and author of the USDA’s Soil Biology Primer, Dr. Elaine Ingham will detail the complex interactions within the soil that make clean water, clean air, and life for higher creatures possible. Learn to foster and sustain the proper balance of soil organisms, and hear how compost tea can stimulate plant productivity and stave off disease. Dr. Ingham is also the founder of Soil Foodweb, Inc. and the former chief scientist for the Rodale Institute.”
I found this to be an excellent and completely fascinating introduction to the soil food web, I’d highly recomend it. This comes in 5 parts and is around 3 hours long in total, I know I’ll be listening to this one more than once thats for sure, check it out and be prepared to learn a lot from this fasinating woman.
PART 2: https://vimeo.com/90902847
PART 3: https://vimeo.com/90908150
PART 4: https://vimeo.com/90913699
PART 5: https://vimeo.com/90913700