Does anyone know why?

nice pictures of another Orchard in Japan.

http://www.socialculinaire.com/profiles/blogs/shizuoka-agricultural-products?xg_source=activity

and, here is another excellent link regarding ffig growing by UK nursery with awesome diagram.

http://www.readsnursery.co.uk/fig-trees-for-gardens-and-greenhouses/

Interesting, he really does say so. Could be there some reasons other than biological/agricultural ? i.e. believes etc. The soil may be a bit more depleted and full of older roots but I think if you work the soil where a tree have grown, the new one should have no problem, right?
Thanks for the link, Grasa!

The main question is why the did the previous tree die. If the issues were cultural (watering, fertilizing,etc.) there probably isn't an issue. But of the issues were soil borne bacteria, pathogens, organisms, and the like they are probably still there waiting for you to plant a new meal for them. I am sure it is more complicated than that, but that is a large part of the essence of the situation.

Many agricultural fields are fumigated to kill soil borne pathogens, sometimes every season, so that carrots, or lettuce, or whatever can continue to be cultivated. It is not uncommon for the same thing to be done before planting a new orchard or vineyard.

Thank you Jon, I was thinking that could be the case, just seemed an odd statement.  

Figue banane = longue d'aout.

One reason I see, for not planting a figtree at the place where there already was one, is if you are changing the variety of figtree.
The old tree could throw shoots, and it would take time to figure out what happened - especially after a cold winter, and the tree coming back from the roots.

I had a brownturkey which roots met a rodent. The next spring I saw it trying to make its way in life, but finally in july it dried. I pulled it out, and found out too late what the problem was.
I then opened a bigger hole to seek for the rodent - but the hole's origin was in the garden of my neighbor ... So I threw some broken glass inside, and put a new brownturkey at the very same place.
Sofar so good ... It is growing on two big stems. Hopefully next year will be its first year of true production... And I'll know to which clan I belong - the ones that like it, or the others :) .
Anyway, should I not like them fresh, I'll go making jam !

I have planted on top a spot where I took out a free tree in the fall then planted the following spring, so far no problems, I took it out because the variety wasn't to my liking.  When I cut down a basswood to plant a magnolia I planted about 2.5 metres away from where the basswood trunk was only because I couldn't dig deep enough closer to where the basswood was, but I cut down the bass wood because it had two main leaders and looked like they could come down either on my neighbours house or mine plus all the seeds clogged everyone's gutters several houses on either side.  I had to also cut down some very old apple trees as they became un productive and planted other fruit trees about 1 metre away, the apricots got canker and were very old refusing to do anything other than drop small fruit, so the nectarine was planted about 3 metres away and so far does not have canker.

Disease is one big reason not to plant on top, but depending on how long it takes for the roots and trunk to break down, I am not sure if they give off plant toxic chemicals as they decompose but for me it's just a pain to deep a big enough hole to plant where the tree was if it was well established.  Never plant near where you had a walnut though, the Juglone could stunt or kill a sensitive tree.

When one cultivates a tomato, a eggplant and a potato in succession at the same place, growth of the plant becomes extremely bad and sometimes dies. This phenomena called as "injury by continuous cropping" or "sick soil". This phenomena is also applicable to fig. To resolve this problems for fig, it takes about 20-30 years.

In Japan, the fig trees often encounter the damage of the long-horned beetle . An imago of the long-horned beetle sharpens the bark, and its larvae eats the xylem. As a result, a fig tree dies.
http://figs4funforum.websitetoolbox.com/post/dangerous-beetle-pests-6670397
http://spygrass.blog102.fc2.com/blog-entry-444.html
http://spygrass.blog102.fc2.com/blog-entry-1329.html

Due to sick soil, one cannot replant at the same place. However, Japan is a small country, one cannot but plant it at the same place. Thus he uses pots and containers.

There is another method to escape sick soil. It is known that "Zidi" is resistant to sick soil. Thus we use "Zidi" as rootstock.

Ah those nasty creatures, getting stronger and hungrier.. must also have chickens to clean them up. I my lay mind, I think the more poison is used in the land, the more they become resistant to it and supersized also.
That is one creature I don't want to encounter.  

Roses are notorious for this.  Continuous amendment with organic material helps to replenish whatever micronutrients are depleted and biologic controls help keep harmful insects in check.

Bob, I was going to mention roses too. It's the same thing that happened with the Irish potato famine...sick soil. All the micro nutrients are gone and if not replenished new plants will not flourish. That's why crop rotation is so important. You plant legumes where the tomatoes were in successive years to replace the nitrogen, etc. Then you can replant tomatoes in following years. Many trees such as euclyptus actually excreet a poison from their roots to prevent plants from growing under their canopy. Once the tree is gone the poison remains until it is eventually leeched out from the rains. I don't know of any scientific testing of fig trees but with their laytex I wouldn't be surprised if they too didn't in some way contition the soil to prevent others from growing there.

I have a few trees I am planning on removing as they just donot put out the fruit in my area. Other than that they grow healthy as can be. Purple magnolia is to late to ripen fruit here, desert king gets killed back every winter along with blue celeste. After trying for a few years I have decided to call it quits with these guys and plant some cold hardy guys in their place. Like nordland, nor de corumb, kathleens black, black greek and spanish, nero 600 and violette barifienge to name a few. Space is an issue so they will be going where some have been before. I will keep posted.