Indoor gardeners attempt to control all the variables. They utilize high wattage lamps and very concentrated fertilizers, nutrients, and supplements which add up to a chemcial reaction stew. Each input has a chemical reaction with the other inputs. The way the inputs are incorporated creates it own unique chemical reaction. These systems can easily and rapidly develop toxic soil and salt conditions which must be flushed (leached) with water. Attempts to control inevitably lead to a wide range of problems and unnatural solutions (along with the ecological cost where the inputs are taken from).
If one were to flush soil with water from a ferrocement water catchment tank problems would arise rapidly. The cement raises the water pH up to 10.3 pH--hardly a plant can survive water of that pH. pH is the measurement of the hydrogen ions--there are entire books about the subject, but simply Calcium, Magnesium, and Sodium are the hydrogen cations. Each cation reacts with other elements in different ways, so there is more to pH than just acid or neutral.
Sounds comlex? Tell me about it. Perhaps some soil chemistry geeks can chime in about the reactions that occur in the soil when water(rainfall, tap, creek are all different pH), fertilizers, ammendments, and organic matter are when they are combined.
Indoor gardeners can quickly witness what happens slowly overtime wiith less concentrated ferts in "conventional" farming and even more slowly over time with irrigation in arid locations--the accumulation of mineral salts. Mineral salt build up is the very thing that the ancient farmers saw over generations in the fertile cresent--the origin of western agriculture. Most of the Middle East is a desert now due salt build up from irragation water from rivers and creeks. Its not the same as rainwater. In arid areas, the high evaporation rates lead to mineral salt build up and must be leached or irrigation must be ceased in order for plant life to continue. Leaching is, well, leaching, so valuable minerals are being removed, especially if people have removed the rocks from the soil--the very slow release fertilizer.
Lets go further. Plants have evolved to certain conditions that concentrated western farm systems and ferts can mimick very well if applied properly. Nature works with slow release fertilizer and little soil disturbance--just like conventional farms use slow release ferts and herbicide. Here is an ethnobotanical equivilant, Hawaiiian's figured out that kalo does best when imported organic matter was allowed to sit undisturbed for a few weeks before planting. I did just that and harvested 25 lbs of per plant. The humus that I added to the soil acted as a long term fertilizer.
When we work with an understanding of how nature works and use nature's best cultivation practices, we can unlock the fertility that is locked out when we do drastic changes to the land via fertilizing, irrigation, tillage, and crop removal. Just look at how much more biomass undistubed nature creates than a farm(understanding that most deserts are created by disturbance). It doesn't need fertilizer or irrigation or added organic matter or sprays to keep pests down. Of course most of the biomass of forests is not edible for us, but we can mimic the forest's best practices to grow our food and take a break.. We can restore the land and have much higher nutrition and production. Nature is like water in the palm of your hand, the more you squeeze it, the less you have. We can even learn how to increase our "palm" size to have more available fertility.
It doesn't happen overnight. It rarely happens within a growing season, but it can. That is my goal for the ornamental foliage and flower farm I am consulting for. We are going to do a rapid conversion to a forest farm. My goal is to have increased profit in 6 months to a year. We will use succesion, intercropping, and an understanding of soil science to increase overall production while reducing expenses on redundant and unproductive action. All this on a farm with a serious case of root knot nematodes, no soil, and a bindweed infestation. If we can do this on rock, it can be done just about anywhere.