Korean Natural Farming Indigenous Microorganisms IMO

The following article is taken from Korean Natural Farming Handbook p.91 to 105.  Some of the English was somewhat clumsy and so the article has been edited lightly.

Indigenous Microorganisms(IMOs)

1. Why indigenous?

Natural farming rejects foreign microorganisms. It also rejects microorganisms that are produced mechanically or artificially or refined simply to increase their market values. No other microorganism adapts with the same strength and effectiveness as indigenous microorganisms that have lived in the local area for a long time.  Domestic farmers who are used to buying commercial microorganisms are amazed at the effectiveness of homemade indigenous microorganisms (IMO). The spread of IMOs and Fermented Plant Juice (FPJ) is giving a new vision for environment friendly agriculture in Asia. We can make microorganisms, widely considered to be one of the most important materials in sustainable agriculture, at home.

IMO is the basis of making fertile soil.

Farming is inconceivable without soil. Therefore adding strength and fertility to soil is the number one priority. What then is fertile soil? Current research indicates that 0.1 hectare of uncontaminated land holds around 700 kg of microorganisms, although this varies depending on how much organic material  is contained in the soil. Of this, 70-75% is fungus, 20-25% is bacteria and 5% is small animals. If we assume that around 80% of their body mass is water then the dry weight would be about 140kg.  Of this dry weight Carbon (C) accounts for 70kg and nitrogen accounts for around 11kg. Given that the suggested nitrogen fertilizer input for 0.1 ha is 10kg we can see that the amount of naturally produced nitrogen in the soil is equivalent.

100 million to 1 billion microorganisms live in 1 gram of soil. In the space of 1 human footprint are to be found 3,280 aphids, 479 fleas, 74,810 nematodes and 1,485 small earthworms. All these organisms live in balance, helping the growth of plants on the land’s surface.

For environmentally friendly agriculture to be successful we need to replicate these conditions as much as possible. In order to bring soil into balance as described above strategies for creating adequate conditions and food for microorganisms and small animals is essential. When you cover hard packed soil  with straw mats and straw for 7-10 days you will witness white fungus proliferating and the soil itself becoming soft and wet.  These conditions never fail to attract earthworms. Thus adding expensive purchased microorganisms to the soil is unnecessary, with some minimal input from humans the soil can recover its strength on its own. In a proper environment (Ian:not sure what this means) fungus microrganisms grow first. Their growth attracts nematodes, which in turn attract earthworms, mole crickets and moles. These organisms and animals restore the balance to soil, improve it’s structure and condition and so help the growth of plants.  90% of the organisms beneficial to plants live within 5cm of the soil’s surface.

When the land is covered by organic material such as rice straw an ideal ratio of shade to sun, 7:3 is created.  Under such conditions water is kept from evaporating and the soil is protected from direct sunlight.  In order to create such an environment a variety of methods are utilized including rice straw or leaf mulching, wild grass cultivation mulching and rye sowing.

You will see from looking at mountains and fields in nature that the land becomes fertile from top to bottom, not bottom to top. Therefore it is recommended that organic fertilizers and organic materials be applied to the surface of the soil in the form of mulching.

Material Circulation

Microorganisms do most of the material circulation in nature (Ian: this is also referred to as the soil food web). These microorganisms break down materials by decomposition as well as creating new materials.  Seemingly nothing is impossible for microorganisms.

Microorganisms in soil are responsible for two main functions.

The first function is to decompose and convert complex organic compounds such as dead plant and animals, numerous secretions and excretions and organic fertilizers into simple compounds such that material circulation is possible.  Inorganic nutrients are also decomposed by organisms and become highly activated and easily absorbed by plants . Weak microorganism action means improper material circulation.

The second function is to synthesize complex compounds and organic compounds. Microorganisms produce a wide variety of such compounds including antibiotics, enzymes and lactic acids. These suppress various diseases and promote chemical reactions in the soil. In the absence of enzymes complex chemical reactions cannot occur at high speed. For example when sunlight strikes leaves it takes less than 1 second to produce one molecule of carbohydrate. Most chemical reactions in the soil and in plants are not likely to occur without enzymes acting as catalysts.  Some microorganisms self synthesize nutrients using energy from sunlight, some fix nitrogen obtained from the air and so enrich the soil.

Many more microorganisms and functions exist which we are not aware of.  Modern scientific knowledge has revealed less than 10% of the soils microorganisms. The soil and the microorganisms which inhabit it remain for the most part a mystery.

Commercialization of microrganisms

As more research is done on microorganisms so there is ever greater pressure to commercialize them. The result has been that large amounts of microorganisms are imported from foreign countries an sold on the domestic market. This is regrettable.

One core issue is how microorganisms can be commercialized. Commercialization is only possible when you can be assured of continued sales and demand.  However this also means that the effectiveness of commercially sold microrganisms be short lived.  And so it is that commercialized microorganisms are indeed short lived  and effective only in the short term. Such microrganisms are short lived because they perish in local soil to which they are not accustomed.

As more emphasis is put on environment friendly agriculture an ever increasing number of of these microorganism products will appear on the market. As a farmer myself I would likely to clearly communicate to farmers that “the best microorganisms come from the local environment and so what you need is all around you and readily available”.

Power of the Indigene

IMO’s have evolved over thousands of years to survive and adapt to the conditions in the local environment. They can withstand the extreme climactic conditions that the environment throws at them. Within their home environment they will perform their function powerfully. Artificially made or imported microorganisms will not perserve in harsh environments to which they are not accustomed and so will die, resulting in short term effects only.

Microorganisms that are made in factories or greenhouses where temperature and moisture are kept constant are only effective in similar environments but NOT where the environmentt is different of subject to change. In the greenhouse there are no typhoons, droughts or floods, but farming has to deal with all kinds of unexpected environmental conditions.  Korean Natural Farming suggests therefore that farmers grow and use local microorganisms at ambient temperatures. I firmly believe that there is no better alternative to using  locally available IMO’s on your fields.

Restoring nature to its pristine state

Some farmers percieve microorganisms to be like fertilizers and vitamins. Acting on this they add microorganisms to the land at a time they think suitable in pursuit of short term effects. In the short run this can give them the results theyu seek. However, in the long term, it can disrupt the balance within a pristine ecosystem of microrganisms.

Korean Natural Farming does not recommend using micro-organisms for a particular function. We believe it is better to restore the pristine state in order to obtain resilience in diversity and restore the soil’s primitive power.

We have to understand that ever more complicated and mechanical, i.e artificial, ways of thinking in farming is only making farming more difficult. The philosophy of restoring the pristine by contrast is very similar to the “Tao” of Lau Tzu. [Ian: An appreciation of nature as a designer is evident in the ‘new’ discipline of biomimicry.]

Plants excretions differ in quality and amount according by season and by age. In turn, the type and amount of microrganisms that live on these excretions also change across seasons.

Bamboo Forests and Leaf Molds abound in IMO

If you look at brushwood fences, bamboo forests or mountain valleys where leaves are piled you will find the white growth of microorganisms. Microorganisms find their best living environments on their own. Farmers in the past would make fertilizer by collecting soil containing decomposed leaves or grass sheets. Below the decomposed leaves or grass sheets IMO abounds.

IMOs are easily found and collected in bamboo forest, deciduous forests, grass roots, decomposed leaf molds etc. In Korean Natural Farming we collect, grow and utilize these IMOs in many different ways.  This treasure exists within our grasp, wherever we may be.

2. Using IMOs

Loss of diversity in microorganisms means that plants lose resistance to diseases. Continued use of indigenous microorganisms not only makes soil and plants healthy but also prevents diseases.

Use IMOs continuously

After practising Korean Natural Farming techniques for 2-3 years you can get lazy with regard to collecting and making IMOs. This laziness begins with the premature assessment that the fields have improved to the point where the effort is no longer necessary.  From there it is a short step to the decision that a little bit of rice wine or lactic acid bacteria will suffice. However, this is far from true.

The MOST important thing in the soil is the primitive diversity and power of indigenous microorganisms. Farmers who fail to use IMOs properly cannot expect to see continued results. Relying on  few substances such as rice wine, despite its being natural, can contribute to disturbing the balance.

Diversity is essential

Modern science was faced with a dilemma as it found out more and more about microorganisms. At first microorganisms were classified into two categories; the good and the bad.  Scientists tried to selectively use what they considered the beneficial ones. Many of the bacteria products you see on the market today are the results of such efforts. However further research has revealed that it is very difficult to classify microorganisms as either good or bad. Additionally, it is extremely difficult to achieve sustained, long term, safe effects using selective microorganisms. It would be fair to say that “the use of indigenous microorganisms is both the simplest and the wisest method”.

Use the tough guy

Anyone who has used IMOs has observed the difference in performance levels of IMOs collected from different regions. IMO’s on the sunny side and the shaded side of the same mountain display differences. They also differ according to the altitude at which they are collected and according to soil fertility.  If you wish to add some tough guys into your locally collected IMO add some collected from high mountains or uncontaminated pristine nature with high vital energy.

The power of diversity

The more sterilized your soil is the fewer microorganisms it will have. This ‘vaccuum of power’ is an invitation for disease causing bacteria to propagate explosively. A web of lively and diverse microorganisms provides the necessary checks and balances preventing this from occurring.  Diseases do not come to you, you invite them in.

If you wish to use diversity to improve your rice crop then you should collect microorganisms that dissolve silicic acid.  Rice absorbs large amounts of silicic acid.  The plant uses this to harden its body. [Ian: the silica content of rice husks and such is so high that research is being conducted on how to use the silica from rice for silicon chips and solar panels. It also causes breathing problems when rice husks are burned in the open air].  Reed,bamboo, purple eulalia lophatherum gracile have similarly hard bodies. The roots of these plants produce a special root acid that dissolves (and absorbs) silicic acid. Thus if you collect leaf or soil from around these plants  it will greatly improve your rice crop.

In the nothern hemisphere the north face of a mountain has lot of psychrophiles (organisms capable of growth and reproduction in cold temperatures), while the south face has mesophiles and thermophiles (medium and high temperatures respectively). On the north face there are no high temperature bacteria  with a fermentation temperature above 70 degrees C,  however you will have  a chance to find them on the south facing slope. Low temperature bacteria will help your crops in cloudy weather, long periods of rainfall and low temperatures. Conversely, high temperature bacteria will help your crops in sunny weather, droughts and high temperatures.

So what do we do? We collect leaf mould and soil from all four faces of the mountain, from the summit, the valley and the drench. [Ian: I assume that the drench is a part of the mountain which is continually waterlogged.] We then mix it and culture it in rice bran.

3. How to collect IMOs

IMOs can be collected using a variety of methods. It can be collected from hills and mountains using steamed rice with low moisture (i.e. hard boiled) , decomposed leaves and bamboo stumps. It is also possible to collect, to a certain extent, particular types of microorganisms.

Collecting from the forest

1.  Fill a wooden lunchbox (preferably made from Japanese cedar) with hard steamed rice. [Ian: I assume Japanese cedar because it is waterproof and decay resistant. I see it used in Onsen a lot.] This rice should not be packed deeper than 7cm to ensure air permeates through to the bottom, preventing anaerobic bacteria from proliferating. Aerobic microorganisms are more commonly recommended.

2. Cover the lunchbox with rough paper (so that the air can get through) and tie it to the box with a rubber band.

3. Bury the lunchbox in the local bamboo field or in decomposed leaf moulds in the hills. Cover it with leaves, Ensure that the leaves are in contact with the paper such that the paper touches the rice surface.

4. Lay down a plastic sheet on top of the leaves above the lunchbox to prevent the rain from getting in.

5. At 20 degrees it will take about 4-5 days (faster when hotter) for the IMOs to fill the box. At this point in time you should move the rice (called IMO1) to a clay pot.

6. Mix the rice with an equal amount of crude (or brown) sugar. The resultant mixture is called IMO2.

7. Cover the clay pot with paper and secure it with a rubber band.

Collecting from leaf mould

1. Go to the hills, forests, valleys and you will find leaf moulds full of white hypha. [Ian: Hypha is also called mycelium and Paul Stamets, the world renowned Mycological expert uses this term.] Collect this IMO mould. Deciduous forests are better as evergreen forests have fewer microorganisms.

2. Dip hard steamed rice in a solution of FPJ [Fermented Plant Juice-coming soon on this blog] diluted at 1:1000 with water. Warm it and then leave it to cool.

3. Mix this rice with the leaf mould. Leave for one night.

4. Add this mixture to rice bran for propagation. Cover the rice bran with rice straw to promote IMO growth.

5. You can add FPJ,  FAA [Fish Amino Acid],mineral A, etc to boost the process.

Collecting from bamboo stumps

1. Choose a bamboo tree in the centre of the bamboo forest.  Cut it down. Cut into the trunk 10cm up from the ground. Cut obliquely with the deeper part of the cut being lower then shallow so that the bamboo sap will not leak out. You should be left with a hollow bowl on top.

2. Fill the bowl with hard boiled rice, the rice should be filled higher than the brim.

3. Put a wooden lunchbox (Japanese cedar) ove the stump.

4. Cover the lunchbox with leaves.

5. Cover with a plastic sheet, and then put a weight on top of it so that it won’t get blown off.

6. After 3-5 days the rice wil be stained  red, white, yellow and black, and all sorts of bacteria will be present. Juice from the bamboo will also be collected.

7. Cut the stump. Pour the rice into a clay pot (this is IMO 1).

8. Mix the rice with an equal amount of crude (or brown) sugar (this is IMO2).

9. Cove the clay pot with paper and secure the paper with a rubber band.

Collecting from the rice paddy

1. After the rice harvest, cover the rice stump with a filled rice lunchbox immediately after cutting. The lunchbox faces downwards.

2. Cover with steel wire to stop mice getting in.

3. Cover with a plastic sheet to stop rain from washing it all away.

4. After approximately 1 week the IMO will have worked their way into the rice.

5. Pour the rice into a clay pot (this is IMO1).

6. Add an equal amount of crude (or brown) sugar (this is IMO2).

7. Cover the clay pot with paper and secure the paper with a rubber band.

When you collect microorganisms from rice paddies, as opposed to other locations, you can obtain a lot of anaerobic (i.e. non air-breathing) microorganisms. In particular you can collect a large quantity of Bacillus Licheniformis (which actively breaks down protein, fat and carbohydrates) and Bacillus Subtilis (which  breaks down strong fibres such as rice straw, straw and reeds). Both of these microorganisms have outstanding decomposition power. However, when the fermentation temperature rises above 70 degrees C they not only convert protein into amino acid but also amino acid into ammonia. Should this occur then the nutrients turn to gas and are lost to the atmosphere. [Ian: Ammonia is also a powerful greenhouse gas]. Therefore, fermentation temperatures should be maintained at or below 50 degrees C.

Lactic acid bacteria feeds on the sugars and amino acids made by Bacillus Licheniformis and Bacillus Subtilis. Adding lactic acid bacteria lowers the temperature.

4. How to cultivate IMOs

Propagation of IMOs

1. The work must be done indoors shielded from direct sunlight; in greenhouses or warehouses.

2. Dilute IMO2 500 times with water and mix with rice bran or flour.  The moisture level of this mixture should be 65-70%. It should be a little wet to the touch. When adding water to control moisture also use diluted FPJ, FAA, Mineral A etc. for better results.

3. Pile the resulting rice bran mixture 30-40cm deep (50-70cm in a cold climate). It should not be on a concrete floor but in contact with a soil floor.

4.  Firmly cover with a straw mat, ensuring that the temperature does not rise over 50 degrees C. To ensure this does not occur turn 3-4 times.

5. Cultivation speed can vary depending on the outside temperature, but it usually takes 5-7 days for the surface to be covered with whitish IMO spores. When the temperature stops rising the fermentation process is finished and you have IMO3.

6. Mix one part IMOs3 to 1o parts rice bran

7. Now mix one part IMO3 with one part soil. 50% of the soil should be from the crop field and 50% should be from fresh new soil (mountain soil, red fine clay, etc). Doing this will ensure that the wild IMOs will harmonize with field IMOs.

8. Controlling moisture preferably with natural farming inputs.

Liquid Cultures of IMOs

1. Fill a pair of pantyhose or a fine net with IMO3. A room temperature of around 20 degrees C and a PH between 6 and * is sufficient.

2. You will then need a 250L opaque container with an air compressor.  Add 0.5L Lactic Acid Bacteria (LAB), 2L Fermented Plant Juice (FPJ), 700-800 grams of brown sugar to 150-160L of water.

[Ian: Though the book seems to omit this important detail I can only assume that the net containing IMO3 is dipped into the water and the compressor turned on. This would similar to what is described on p.137 of the book Teaming with Microbes in relation to brewing ‘actively aerated compost teas’:

“some people put their compost in a porous bag before they put it into the tea brewer rather than allowing it it mix freely in the water. A pair of large sized pantyhose works well as such a compost sock.”

There appears to be a lot of crossover details between making IMOs and making actively aerated compost teas. the main differences seem to be the source materials and the IMO fermentation process as opposed to composting. ]

3. Depending on the the culture temperature the fermentation process takes between 5 and 7 days in Spring and Fall and 10 and 30 days in winter. Depending on the cultivated state the resultant mixture can smell either sweet or nasty, a sweet smell is desirable.

4. Often a sludge will appear on the surface. This sludge is composed of microorganism corpses. This can occur when food or air is lacking in the solution. If it occurs add more air, or add FPJ.

5.  Replacing the IMO in the sack every once in a while can also be beneficial.

6. Depending on need use 40-50 litres of the liquid at any one time,  refilling the tank with water while adding more food for microorganisms. The basic dilution is 1000 times, but can be as strong as 500 times  depending on the need.

[Ian: My reading of this is that the liquid in the tank should be diluted on the order of 1 part to 100o of water. Keep in mind these input instructions are designed to supply a working farm with all its fertilizer so the amounts would be huge for a garden or allotment.]

Chemical fertilizer can be added to the solution. The solution can then be used 7-10 days later after the IMO has had time to act on the chemicals. Adding too much chemical fertilizer at once can stop the fermentation process. Therefore it is important to introduce the chemical fertilizer to the tank in adequate amounts slowly. The yeast bacteria so abundant in FPJ are excellent decomposers of chemical fertilizers; converting them to easily absorbable mineral forms. Using chemical fertilizer in this way will greatly reduce soil degradation and the nutrients will also be better absorbed by plants.  To duplicate the effect of nitrogen use ammonium sulphate or urea. To duplicate the effects of phosphorus, use superphospate or double superphospate. To duplicate the effects of calcium use quick lime.


  1. Hector said,

    March 11, 2010 at 11:20 am

    hi man …

    I was wondering where can I get the KNF handbook?

    I’m from Mexico and I’m thinking on make some experiments using this KNF.

    Thanks in advance

    • August 31, 2010 at 3:28 am

      Hi Hector,

      Sorry for the tardiness of my response. New baby, new country, new job. It’s been pretty hectic. Now as for a response..

      One of the reasons I started putting this stuff up on the web was that in my experience the handbook in English is ridiculously difficult to get hold of. You might try enquiring with the Asian Productivity Organization in Tokyo, since they have trained farmers in Asia on these techniques. Alternatively, you could enquire with the Korean Productivity Corporation in Seoul. However, the best bet would be to contact Janong USA and make enquiries there.

  2. michelle ajamian said,

    March 16, 2010 at 6:45 am

    do you know how to find a copy of the book? i am interested in reading more on this technique.

    • August 31, 2010 at 3:38 am

      Hi Michelle,

      A lot would depend on where you are. If you are in North America I would recommend you approach Janong USA directly. There website is located at: http://janonglove.com/janongusa/intro04.html. I hope that helps. I’ll be trying to implement this on rooftops, something which is not listed in the literature.

  3. Reyvelyn Palomar said,

    March 23, 2010 at 3:53 am

    I started my IMO collection two weeks ago and I don’t know what to do next. The notes I have are short and bit confusing. Now, I have an idea on what to do next. Thank you.

  4. Louis said,

    June 4, 2010 at 5:55 am

    very cool stuff man! where can I buy the Korean Natural Farming Handbook Please

  5. October 20, 2010 at 9:08 am

    where can i buy korean natural farming han book.

    • November 24, 2010 at 12:20 pm

      I would contact Janong USA for details on how to do that.

    • March 12, 2011 at 10:20 am

      Hi Nageswararao

      I just sent a copy of the book to Eric Toensmeier, author of Perennial Vegetables. I could probably do the same for you. Send me a message.



      • sam said,

        May 2, 2011 at 5:19 am

        hi Ian, just went thru yur blog and am amazed how benificial the korean natural farming method works, i would thankful for a copy of the hand book too.
        please keep posting/updates on the rooftop project.. i’m curious how it works out on a surface without contact with the earth.. interesting..
        thx sam

      • May 29, 2011 at 11:05 pm

        Hi Sam,

        Yeah, Eric Toensmeier, author of a book on Perennial Vegetables was pretty amazed too. If you send me an email, I expect we could figure something out.



  6. James said,

    February 10, 2011 at 4:33 am

    Hi there,
    I agree with you on the use of IMO for good and natural agriculture practice.

    We have successfully produced IMO based fertilizers and it has undergone many test and trials in our local estate and plantation in Malaysia, Vietnam, Indonesia, China, Singapore and etc., with overwhelming results. With our fertilizers that source solely from the nature, we have managed to bring almost dead trees and seemingly dead trees back to life.

    Apart from lower cost and smaller dosage in comparison with chemically produced fertilizers there are many advantages and benefits to the estate and plantation owners – Better Yield, Storage space, Lower Transportation Cost, Better & Lasting Produced and etc.

    In all aspects the IMO based fertilizer should be considered if one is caring enough for the nature and environment. Our IMO based fertilizers bring back the best of nature to the environment.

  7. Joesany said,

    March 20, 2011 at 8:19 am

    hello sir,

    what are the specific microorganism can we collect in that process?

    thanks more power….

    • May 29, 2011 at 11:12 pm

      Hi Joesany

      Science has catalogued about 1% of the bacteria, fungi etc that live in the soil. So I’m not able to answer this question. The components self assemble. Imagine a million different kinds of thing in the IMO and t\hen multiply that by the number of interactions. I think the number you’d get would be on the order of the number of connections in the human brain.


  8. Scott said,

    May 7, 2011 at 2:03 am


    Could someone please explain exactly what mineral A-E is? Cho does not tell you in his book.



    • May 29, 2011 at 11:02 pm

      Hi Scott,

      This is a very good question. I wish I knew myself. Unfortunately, it appears that there are exceptions to the DIY credo set forth in the manual and this is one of them.



  9. June 25, 2011 at 2:00 pm


  10. sweets said,

    March 20, 2012 at 1:23 am

    Thank you so much for this info….indeed it help m a lot in improving my thesis ……keep posting…God bless…

  11. s k das said,

    November 9, 2012 at 6:13 pm

    we are practicing Dr.Cho s’Natural Farming technique. it is quite easy and tremendous.The smell less poultry farm,natural vegetables etc one will like to test.

  12. s k das said,

    November 10, 2012 at 9:34 pm

    If any body intend to know more regarding the IMO and its use in Agriculture, Livestock,Fishery we like to share our experiences , one can also visit our massive cultivation field..

  13. December 8, 2012 at 8:55 am

    hi i would like to know how one can use imo to ferment cow dung, saw dust and soil as pig feeds, other wise its doing remarkable work with farming thanks, allan from Uganda.

    • August 28, 2014 at 1:29 pm

      Dr. Cho’s methods allow for livestock to be kept in corrals and small areas on floors of their own composting feces and urine with no disease or smell. This seems counterintuitive I know. However, Zero Emissions Research and Initiatives provides an answer. Everything in nature is food for something else. The bacteria in the IMO actively break down and digest waste products within the barn or corral.

  14. March 31, 2013 at 1:38 pm

    Great, I think I should not only look on and marvel at your explanation but I am going to begin using the IMO straight away in the piggery

  15. April 18, 2013 at 9:35 pm

    Many thanks for sharing superb informations. Your site is very cool.
    I’m astounded by data that you’ve on that website. It reveals how nicely you perceive this subject. Bookmarked this site, is for extra articles. You, my pal, ROCK! I noticed simply the info I already searched all over the place and simply cannot come upon. What an excellent web site.

    • April 21, 2013 at 2:39 pm

      I simply cannot take credit for this. All I have done is take Dr. Cho’s work of genius and put it on the web, where people can find out about it.

  16. sha said,

    March 13, 2014 at 4:11 am

    I have applied this IMO for production of medicinal plant it resulted in a good organic production

    • August 27, 2014 at 2:18 pm

      Dear Sha


      Which medicinal plants did you use it on?



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: