Solucan Gübresi Bilgi Portalı 03 Aralk 2016

A Stunning Interview with Josef H.Görres About The Worms

A Stunning Interview with Josef H.Görres About The Worms

Who is Josef H. Görres?

Josef H. Görres defines himself:

Vermont’s economy depends on agriculture and thus soil is a central resource. My teaching and research connect ecosystem services with agricultural economics for the sustainability and prosperity of farms in Vermont.

Academic Career:The University of Vermont

  • Ph.D. University of Manchester Institute of Science and Technology UK 1982
  • M.S. Natural Resources Science, University of Rhode Island 1991
  • B.Sc. Physics, The Victoria University of Manchester, UK 1979


Savaş Gönen: You received training as a physicist and now you are doing research on soil. This is very unusual  for a scientist in Turkey. Can you tell us about the starting point of your adventure on your Works. And of course the relationships between physicist and soil? Why have you been interested in worms?

Josef Görres: I actually wanted to be an astronomer when I was growing up, but eventually I found out that there were few positions in astronomy so I changed my specialization. Physicists work with complex systems. Soils are very complex because they have a lot of different habitats (pore spaces) for different organisms that do different things in the soil. Much of hte physics of porous solids can be applied to soils and of course you have physics of water flow, nutrient and pollution transport, and even the  sensing of chemicals by organisms you could explore.

SG: To start with, I want to ask a basic one: What can you say about  the pros and cons of worms? Is the vermicompost really a gold for soil and organic agriculture?

görres foto_1JG: Vermicompost may have many benefits. These are in soil fertility and plant nutrition, plant growth regulation, improved soil organic matter, some protection against plant pathogens. Of course a vermicompost is only as good as the materials you use for it. The materials should be as free of heavy metals as possible.  You should combine materials with high Nitrogen content (e.g. manure) with materials high in carbon (for example straw, wood chips etc.). The initial C:N rationshould be 30:1 and over time (2 – 3 months) should be reduced to 10:1-15:1.

Here in Vermont there is a dark side to earthworms. All earthworms in New England are exotic and some are invasive. The can damage would lands by changing the soil structure and thereby reduce the understory of the forest vegetation and even prevent the regneration of trees.

SG: In terms of organic farming, do you think vermicompost is an effective alternative to chemical fertilizers?

JG: Organic farming by definition does not use chemical (inorganic) fertilizers. Vermicompost has a high available nutrient content in comparison to other composts. It can act very quickly. So as a supplement or as a starter fertilizer it will be effective. It is expensive when it is produced commercially but maybe at a small scale it is cheaper. It can be used also as a way to produce very strong seedlings before planting in the field.

SG: You say “native plants may not adapt to the fast release of nutrients that earthworms cause”. This is a very important determination. Starting from this, is there any problem about the commercial production of vermicompost. For example, in this respect using commercial vermicompost in all kind of agricultural facility pose any danger?

JG: Release of nutrients from earthworms in natural settings can be a problem where ecosystems have not developed in the presence of earthworms. For instance, ecosystems in areas that were covered by glaciers 10,000 years ago (ice age) developed with earthworms. So the plants that grow there are adapted to different time periods for leaf out and flowering than when earthworms begin to be active. That is a problem in many of the invaded woodlands. Sometimes this pattern may encourage invasive plant species to colonize the earthworm-invaded forests which can interfere with the harvest of trees and reduce biodiversity.

On farmland things are a bit different because here you can manage the land and your crops more easily. For example you can use cover crops to take up the nutrients released by earthworms. So for a regular farmer its not much of a problem. Some earthworms, however,  may create deep burrows through which some of the chemicals applied by farmers may leachout of the root zone and that is a cost to the farmer because the chemical cannot act on the plant because the plant cannot pick it up…

SG: “Common believes are that earthworms have positive effects on soil health and on ecosystem function.” But quite the contrary, if “some potentially negative aspects of earthworms activities” is there, what kind of measures can take an ordinary farmer about these negativeness while using or producing their own vermicompost?

JG: It would be prudent to separate the earthworms from the compost for a bunch of different reasons:

1. Earthworms can be sold at a good price;

2. Composting earthworms should not make it into the fields.

SG: What is the difference between native and invasive eartworms? By the Assoc. Prof. Dr Mete Mısırlıoğlu’s book “Earthworms, Biological, Ecological and Turkey Types”  (Toprak Solucanları, Biyolojileri, Ekolojileri ve Türkiye Türleri), there is very kind of worms in Turkey. Supposing the farmers that using the vermicompost produced by Eisenia foetida, that is not a native worm for his region, will be any danger that you mention in your Works about invasive eartworms?

Josef Görres, M.Hanifi Can and Dr. Korkmaz Belliturk

Josef Görres, M.Hanifi Can and Dr. Korkmaz Belliturk

JG: I think really that the E. Fetida should not be a problem because it requires a lot of organic matter to persist in an ecosystem (that is why it is a good composting worm, it can deal with a lot of organic matter). But, you never know…!  There is very little known about invasiveness of earthworms in Turkey and which earthworms are exotic.. The earthworms that are classed as peregrin and they have spread around the globe. These include some of the Lumbricus species (L rubellus and L terrestris) but htere are others. There approximately 70 different recognized species in Turkey but most likely there are many more that have not been collected yet or not even been described as a species. So I can’t really say much about hte danger of exotic earthworms in Turkey. However, Mete Mısırlıoğlu lists earthworms of the genus Amynthas. Thesea re from the far east (Japan, China, Korea) and they may pesent a problem as they are aggressive invaders of forests…

SG: How can we determined the invasive worms?

JG: Good question. We know so little about the earthworms of Turkey that identifying exotic invasive ones is difficult. Invasive earthworms have a number of important characteristics: 1. Fast reproductive cycles; 2. Consume a lot of matter quickly; 3. Adapt to new environments quickly…

SG: I have a question attached to mind? Do not show the invasive worms same devastating effect (just in Vermont, in Great Lakes…) on their own countries of origin? If not, why or how?

JG: Invasive organisms do a lot of damage where they invade because they are not controlled by a predator that may exist where they were from originally. So in their original habitat they may not occur in the same numbers because they are in equilibrium with the rest of the ecosystem. Also the original ecosystem may have an earthworm component to it which may make it unique there. If the earthworm is transplanted into a new environment it  causes damage.

SG: It is said that , according to Peter Groffman, “worms  eat leaf litter which acts as a rooting medium for new growth”. But in a lot of articles it is written that worms only eat the rotten materials. In that case, how can the  eartworms eat undecomposed leaf litter? If leaf litter decomposed, then what is the difference between decomposed leaf litter and worm casting as a seed germination medium?

JG: Any leaf litter on the ground will begin to decompose quickly. In fact the chemistry of the leaf has already changed when it falls of the tree. Earthworms contribute to the decompostion. Earthworms could feed faster if the litter had been shredded by insects… So in some ways the leaf litter is already rotten. Some earthworms actually drag the leaf litter into their burrows where they rot and then the earthworm feeds on microorganisms that are growing on the rotting leaflitter…

SG: We all know that worm casting is a good rooting and germination medium! Isn’t it? A person says “when worms process material, they leave behind castings. Castings are known for being loaded with beneficial bacteria, and are known for making your plants THRIVE. Why would this area, in the forest, show no growth?” What do you say about this statement?

JG: Castings are used in horticulture to grow plant seedlings that can be sold and transferred into fields. So yeah castings are great for germination.

Plants that are in forests that developed without earthworms require the light layer of organic matter that is common to many forests (without worms). That is where the seeds are stored (seed bank) and where they germinate. Castings in forests are often mixed with mineral soil so that a dense layer of soil develops that seeds roots of original plants cannot penetrate. Yet, some invasive plants that come form forests with earthworms may be able to germinate…

SG: What is the real story about worms and carbon? Is it possible that all the carbon released into the atmosphere by the fast decomposition? If so, what can commercial vermicomposters do about this issue? Is there any danger for them?

JG: There is no danger to the farmers but there may be an effect on climate change which has not been evaluated scientifically yet. However, many workers have looked at greenhouse gas emissions from earthworms in soils and they have shown that there is an increase in CO2 from those soils.

SG: In an article that Tim Filley working on, a Purdue University environmental chemist, it is said that “Earthworms’ appetites may facilitate carbon storage so the chemical isn’t released into the atmosphere as CO2, which potentially could help curb climate change”. Is it really possible  that earthworms can cause a change on this scale? Does the same thing apply to commercial vermicomposting?

JG: Maybe. We are actually working on that question right now. One of my studnets is looking at carbon storage in woodlands with and without earthworms. The main idea si that earthworms create aggregates and pores in these aggregates may be so small that microorganisms cannot access the organic matter.  That is called physical OM protection. WE are also measuring greenhouse gases from vermicompost and compost operations…

SG: From the Wageningen University, Jan-Willem van Groenigen implies that, “scientists have been slow to understand the little organisms’ role in the carbon cycle”. For him, “when they(worms) excrete the remains, their droppings provide a feast for soil microbes that emit nitrous oxide. Their burrowing and churning also mixes plant matter into the dirt, where it decays and produces carbon dioxide”. So which one is true; carbon storage or emission? On the other hand, Groenigen  says “there are hints that over longer periods, CO2 emissions from worm-ridden soils may decrease while nitrous oxide emissions may rise”.  As a result what can you say about these confusion?

Josef Görres(right), M.Hanifi Can(middle) and Dr. Korkmaz Belliturk (left)

Josef Görres(right), M.Hanifi Can(middle) and Dr. Korkmaz Belliturk (left)

JG: Truth is a matter of knowing all processes. If you look at the effect of earthworms on soil CO2 emissions then yeah, they will have an effect. However, part of the leafs that are incorporated into the  soil may actually become protected from decompostion when they become part of pore sapces that are too small for microorganisms. There also seems to be a fast effect of the earthworms (i.e. CO2 emission) and a slower effect (protection of C). It is the  balance of the two processes that you need to look at. Both processes occu all the time.  How muchis stored in teh soil is a question of the difference between the processes. Its like your checkbook: money goes in and money comnes out. How much money is in your account depends on how fast money is deposited and how fast you are spending it.

SG: In the project named “EARTHWORM MEDIATED LOSSES OF N FROM DAIRY AND MAPLE PRODUCTION SYSTEMS IN VERMONT”,  it’s said that “in particular in soils with earthworms nitrogen was almost exclusively nitrate a form of nitrogen that easily leaches and that might be transformed into nitrous oxide, a greenhouse gas.” Does the same thing hold true for the situations that  the commercial vermicompost used.

320px-Nitrogen_Cycle.svgJG: Yes. But whether something leaches dependson soil management, the type and amount of stable carbon available etc.  In order for NO3 to develop it first ahs to go through the ammonium (NH4) stage and if you can disrupt nitrification (NH4 goes into NO3) somehow you can protect your nitrogen from elaching. This can happen if NH4 is sorbed onto the Cation exchange capacity of clays and organic matter, or it may happen because microorganisms and plants take it up as soon as it is formed. In fact somebody has shown that if you add additional high C straw to the vermicompost you can save as much as 10% of the N that is usually lost in the process… And that would be due to microorganisms taking it up while decomposing the straw.

SG: In the article written by Michael Tennesen,  published in  Scientific American, especially night crawler (Lumbricus terrestris) and Alabama jumper (Amynthas agrestis) are the most harm to the soil. But lots of people use such kind of worm species for vermicomposting. Isn’t there any contradiction?

JG: Neither Lumbricus terrestris or A. Agrestis are good composting worms. L terrestris is an anecic worm (for definitions of ecotypes see Mısırlıoğlu’s book) and does not reproduce fast enough. However it is big enough to cause a lot of damage in woodlands. A. Agrestis has a lot of off srping but it takes about 90 days to mature before they can reproduce. Compare that to an E. Fetida that can reproduce after 20- 30 days.

SG: What can people do to help the forests recover? Is it not possible to go back to the beginning again?

JG: There are no real controls for earthworms in forests. The main thing is to avoid invasion. Once the invasion ahs occurred that is it. Somebody has suggested flatworms, which prey on earthwomrs and are natural predators, but hey themselves could become invasive. However, we have tried some organic insecticides, some have tried controlled fires … Other than using some really nasty chemicals there is little you can do… Wait for the next ice age.

SG: Allison Jack  said that “in populated areas and especially agricultural areas, invasive worms like E. fetida brought by early European settlers are pretty much naturalized in manure piles and any other high organic matter areas”. Is it possible to say that E. Fetida is not pose any danger anymore? Perhaps in time, the others will be naturalized too. Do you agree?

JG: Only because somebody says the worm is nturalized does not mean it could not do any more harm. I do not agree… In 1000 years time an ecologist will look at earthworms and say they are from here… because that scientist will probably not look at the sme ecosystems anymore. Teh systems will have changed and the memory of what is here now will have vanished.

SG: If the nutrients have leached through earthworm burrows, can we suppose that, as suggested by some people, inoculating the worms to the field is not a good idea?

JG: The main worms that do this are anecic earthworms (Mısırlıoğlu’s book) because they make deep vertical burrows which are large channels that can leach things rapidly out of the root zone. The other earthworms do not ahve that effect. E. Fetida is an epigeic worm that does not make deep burrows and will spend its time in the organic layer of the soil…

SG: What do you think about the products obtained from worms? For example, worm tea, leachate, vermiwash, worm meal… As well as in invasive worms, are there any points on this subject that we missed?

JG: The extracts that you can make from the vermicompost can hae beneficial effects on plant resistance to disease. Cool stuff… You got a lot of the points covered.

SG: Is the vermicompost, derived from biomass really useful? In your opinion, vermicomposting operations for the disposal of sewage sludge work?

JG: Sewage sludge has to be very well screened for heavy metals. Humanure (as it sometimes called) can be difficult to use as a feed stock because sewage works often receive waste water not only from households but also businesses and then it is very difficult to control pollutants that don’t break down in the composting process. Here in teh States and in Europe there are some really good examples of biosolids or humanure utilization. There are some cities that have excellent recycling facilities that integrate sewage wastes into their program. Also, if you use the humanure (biosolids) for non-food production, such as horticultural flower beds and road side plantings you may not have to be quite so stringent in your quality control.

SG: I know that you are in Turkey for a while. What are you currently working on in Turkey? Can you tell us about your studies in Turkey?

JG: My colleagues at Kemal Namik U. and of the Olive Research Station in Izmir are planning a survey of earthworms in Turkish agricultural fields. There is little known about earthworms on farms. Several surveys have looked at earthworms in forest and natural lands but in fields and orchards little is known…  I will be involved in that study if it is going to be funded by Tubitak … I am hoping that I can also help with vermicompost research in Turkey. Both projects would be fun to work on. We are also hoping that we can obtain a BREAD grant from the Gates Foundation to investigate how agricultural waste materials can be utilized as fertility amendments by smallholder farmers to improve their income. Of course all of these are dependent on funding sources.

SG: We are far behind the world’s production of vermicompost as Turkey, many years later we started. So, what do you think about the work of vermicompost in Turkey?

JG: Vermicompost operates at a very local scale. If you have to move feedstock materials for vermicompost from very far away it becomes less profitable… So the fact that a country has started vermicomposting later than another does not matter. The potential for producing a high value fertility amendment is still great. In some ways starting alter is an advantage because Turkish vermicompost producers can ebnefit from research that has already been conducted in other countries. I cannot emphasize enough the local nature of vermicomposting. The research that is needed would have to be done on identifying and characterizing the typical organic wastes that can be used as feedstocks. In Turkey this would be different kind of manures (sheep, goat, cow etc.), olive and grape pumice etc …

SG: Finally, what else you want to say about worms and vermiculture to the fans and/or farmers in Turkey? Any advice?

JG: Do it but educate first what you have to do to make agood compost. Separate teh worms from the compost….  Don’t rush the compost, give it time to mature. Some say you can get it in 1 month but 3 months gives a much better product….

SG: Thanks for your answers!

Click here for the Turkish text of the interview …



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