Backyard Aquaponics
A place to discuss aquaponics

Aquaponics takes advantage of natural cycles to harvest food. Agriculture, while it may appear terribly wrong from the perspective of natural ecosystems, has enabled 7 odd billion of us to live on this planet, you can't deny it's success. Nutrient cycling approaches are surely an improvement on input-output approaches which degrade terrain, produce wastes etc, but at the end of the day, if you want to eat you have to plant crops, kill weeds and "interfere" with the "natural balance". Permaculture has a lot of useful insights and decent principles, but it should inform and educate a new kind of agriculture, we can't all go back to being hunter-gatherers!

To understand better, also look at rain forests.
i used to think rain forests must have the best, most fertile soil anywhere.... but i was dead wrong.
it is pretty baron sandy soil deeper down usually, with a decaying layer of nutrients on top.... with the vast source of nutrients being held in the trees themselves.
so as you said, once cleared there is a certain amount of time that the soil seems good, but goes down hill very quickly after that.

im sure many systems work a similar way, grasslands hold so much nutrient within the grass and although the area may get stripped of nutrient (eaten), anywhere that gets eaten in nature, also gets many deposits from grass eaten in other areas earlier on.

mycorrhizal fungi plays a large part in the success of the forest too, although all forests are warzones between the plants, the fungal systems in rain forests also mean that they all support each other, a seedling which can not get any where near enough light to survive normally will do well once tapped into the forests fungal systems, as the fungus feeds it with energy produced at the forest canopy.

" a seedling which can not get any where near enough light to survive normally will do well once tapped into the forests fungal systems, as the fungus feeds it with energy produced at the forest canopy."

Interesting. certainly another angle to look at.

Thanks a lot.

^ that isnt going to work in a home garden too well, i dont think all plant systems develop such a large communal fungus, most plants just have their own localised on their own roots, if they are even lucky enough to have such a relationship.

I agree with you a mature forest should have a commensurate soil ecosystem. But a small garden should have at least something. Just as above the ground when plants starts to grow other lifeforms come joining in. And as you said one tree requires a vast amount of nutrients a home garden should require less.

The plants themselves are the soil builder, leaves, broken of limbs, dead trees, old grass and so on decay, occasional wildfire.
Even if it looks plush and lush, its never a mono culture and if you take a close look, its never overplanted, it is just enough and only the plants that fit.

I guess there are couple things here...

the most 'visually productive' man made gardens I see are botanic gardens. Perth is very dry yet our zoo for example has some very lush sub-tropical garden areas shaded by large trees. Water is obviously a factor, but while they probably fertilise a bit it is not really significant to the number of plants. so water plus types of plants is a factor, and these develop their own little ecosystems based a lot on leaves and the bugs etc that break ground litter down.

Yav's example of rainforests is interesting one. In particular sub-tropical rainforest. They benefit from warm temperatures, constant damp, weathered soil profiles and large insect/organism biodiversity. These are conducive to rapid conversion of waste to nutrients. A lot of rain water is detained within the plant canopy and ground surface and a lot infiltrates the soil. Most importantly it does not experienece extremes of heat and cold (it is insulated to some extent). When you clear a rain forest (eg. in Queensland) you add light, wind and heat = dryness. You also break the waste cycle and inevitably it is no longer a suitable habitat for organisms. The soil clogs and water runs off creating erosion. It takes a lot of effort to re-establish a sub-tropical rainforest vegetation profile.

Agriculture is mostly about exotic plants that have demands outside of the domain of the local environment/situation.
Humans are also seeking growth rates that require nutrient uptake are not sustainable in natural systems.
Hydroponics is the best example of that. Supply the right nutrients then plants grow - the rest is pretty much optional. But it is definitely not sustainable and a natural system could never establish on those conditions. In agriculture cases a bulk of the nutrients are removed every cycle (the bits we eat).


Native plants as a rule have very low fertilizer demands. But very few of them are particularly nutritious.
Most also exist on a boom & bust scenario - ie. they optimise when times are good and diminish when hard times come around. These cycles represent fallowing and green manuring in many grassland systems (where crops like wheat, oats and barley etc come from).

As a throw in re: last post the most incredible example of nature minimilistic requirements are coastal sand dunes. The marine sand has no nutrients what so ever. When they get sheltered full vegetation systems establish - particularly in the low points where water and any nutrients accumulate. Plus replenishment by sub-surface watertables and groundwater helps.

The interesting and opposite situation are exotics/introduced species that do really well. eg. Plants from Africa quickly create issues for places like Australia. Plants (and animals) from South America create issues in sub-tropical areas. Mostly it is about them having better conditions than normal (more light, rainfall etc) and no competition. Australian Eucalypts for example have created problems in middle east and northern africa - they have fast growing tap roots that can find subsurface water and extract some nutrients (minerals that way).

In context of the original question "is nature unfair ?"
It is more a case of nature does not support gluttony - so things that remain in balance can persist while things that want more than they need deplete the accessible resources and cannot survive.

So far humans are the only exception to this rule...

it does raise the question between failed civilizations (ancient urbanization)...
versus the longevity of nomadic living cultures.

If you take into account leaching and erosion. "The plants themselves are the soil builder" theory wont hold up. Your lettuce garden is only 1 foot high. Try to compress the forest canopy to 1 foot and you'll see how densely planted it is compared to your garden. I remember having to take a shortcut from one of the mountain expedition. and I found my self on a grassland where its impossible to walk so what I did was to gather the grass as as go and walk on top of them. If I fall that means the grass is not to dense and so I crawl underneath. This goes on for more than two hours, up, underneath and up. The slope is at least 30 degress and the grassland been there for decades maybe hundreds of years without depleting the soil. How do you account for plant nutrients carried by the rain water to the creek which is at the bottom of the grassland? and how about the occasional wildfire that turn nutrients to smoke. and afterwards the plant came as healthy as before. Does "soil ecosystem feed the plant" theory can explain this all?

as a rule the nutrients don't go to smoke. It was quite common in Australian crops and native grassland to burn and experience vigour. This is a bit of a fallowing outcome. It is only that green manuring (dead stalks and material breaking down on location) that is a more effective return and you don't get the "greenhouse gasses" of smoke. Vegetation (bushfire) smoke is mostly carbon particles and compounds (CO2, hydrocarbons etc)

Nutrients in well grassed/vegetated areas don't generally make it to watercourses.
I work in hydrology and if you want to reduce P and N loads then you simply plant native grass or vegetation buffers - it is very effective.
Most nutrients adsorb/attach to soil particles, so soil erosion is a greater loss of nutrients then any other mechanism - so is most likely the consequence of clearing steep areas.
That has been shown to be true in Australia, US, India and Africa (where most research has been done) - also many parts of Asia.

In stream rehabilitation even buffers only 50-100m wide can significantly reduce nutrient loads.

>> If you take into account leaching and erosion

it is no accident that plants are more lush at the bottom of hills than the top....
or that river deltas and flood plains are the most fertile areas.
Soil + nutrients + chemical leaching (eg calcium) are all better at the bottom of a slope.
However volcanic ash etc add nutrients back into the uplands as does the weathering of insitu rock.
The natural acidity of rainfall plus the plants themselves help break rock down into basic elements.

Thanks Darren, good info. Still there are loses to nutrient from plants. Over the course of hundreds of years this loses no matter how small should deplete the soil. Since it is not depleted it means there is something that replenish it. That is my point here. Since you knew better than me in this subject, where do you think the replenishing comes from if not from the soil.
Then of course there is the very obvious fact that any barren land will soon become a forest by simply bringing in the seeds. by wind insects birds and rodents. First the grass then the herbs bushes and then trees each smaller plant seems to serve as a host to the bigger plant. If the "plant makes it own nutrients" argument is true how would you explain starting from nothing to lust forest. Even if we start from grass, grass creating nutrients for lust forest is the equivalent of over unity device

>> If the "plant makes it own nutrients" argument is true how would you explain starting from nothing to lust forest. Even if we start from grass, grass creating nutrients for lust forest is the equivalent of over unity device

It is a case that plants contribute a lot to soil formation and the breakdown of rock etc.
Lichens and mosses begin to break rock down, and larger plants expose rock cracks etc to weathering.

Nutrients can also blow in with dust and ash. But these processes take a long time.


There is no doubt that if humans walked away from a 'depleted' paddock it would grow some form of vegetation again - in cases very quickly *IF* the climate is accommodating. Even 'degraded' agricultural areas recover to something in 10-15 years - I have seen this.

The only exceptions appear to be the Arab and Northern Africa areas which were probably much more vegetated and the desert sands much less extensive. But they are fragile landscapes where climate and water is a big factor - and it is suspected early civilisations probably consumed massive amounts of wood.

"It is a case that plants contribute a lot to soil formation and the breakdown of rock etc.
Lichens and mosses begin to break rock down, and larger plants expose rock cracks etc to weathering."

Thanks again Darren. does this mean that veggie plant or other plants that is planted by humans dont contribute to soil formation, because after all being planted with veggies the soil gets depleted. does this mean that only wild plants contribute to soil formation. That is why they dont need additional nutrients from man no matter how many thousand years.

Thanks again Darren. does this mean that veggie plant or other plants that is planted by humans dont contribute to soil formation, because after all being planted with veggies the soil gets depleted. does this mean that only wild plants contribute to soil formation. That is why they dont need additional nutrients from man no matter how many thousand years.

Usually these are locally relevant plants whereas agriculture plants tend to be much less hardy and more demanding of an easy feed.

Hard to provide you with a Philippines relevant example as I am not familiar with that situation.

If you look up ecosystems and ecological succession many text books talk about the pioneer species.

For example in Australia a lot of agricultural land has gone saline (salt affected).
Now if man puts a fence around it to exclude animals and walks away very soon after a suitable rain etc plants called samphires begin to colonise. These area succulet with low water and nutrient demands. When the water flows they trap sediment and nutrients and grow more samphires. As they get more dense larger sand beds form - from both water flows and dust/sand that is blowing around. When the sand beds gets larger after some years other seeds that are blowing around get trapped in amongst the samphire and eventually shrubs etc start to grow. I have seen this happen - albeit with some human assistance. But we couldn't plant any 'seedlings' ourselves that would survive because the ground was too hostile. Yet over 10 years nature slowly does it.

The lichens etc are well published. Some types create chemicals etc that can help break the rock down.
I seem to recall it as a classic example in some of the Ecology books I read many years ago in geography.

try this... gets heaps of hits..

I have updated my rule to "nature does not support gluttony (excess consumption) and nature rewards things with lots of patience"

someone once asked me "are you religious and do you believe in God etc"... my reply was I wasn't sure but I definitely believed in Mother Nature.....


p.s. In the Philippines I am sure that if your farmer walks away from his depelted field that "wont grow anything" there will be all sorts of weeds and vegetation established within 6-12 months, and probably some form of 'jungle' within 1-2 years That would be pretty true of most areas in SE Asia. So its not about soil formation in that sense - it is about who/what is tough enough to survive there on what is available.