Organic is a marketing term. There is a definition of strictly organic that is regulated by the National Organic Program. There are strict rules growers have to follow to be certified organic and be able to put an organic label on their products.
Organic usually means you have to use products that basically came from something that was once living. This includes composts that are aerobically made like your garden compost pile. (to be strictly organic, all inputs must be organic, so no synthetic fertilizer in the starter pile.) It can also be naturally made anaerobically like peat moss.
Allowed pesticides and fertilizers are either organically based from plant oils and residues, animal byproducts, or naturally occurring minerals, and elements. This excludes manmade fertilizers like urea, althoug pee is allowed. GMO is manmade, so by definition any GMO cannot be organic.
To be certified organic you have to document that you have used only organic inputs and methods for 3 years to be certified to be able to use the organic label.
At home, you don't need to be certified, but you should be using organic amendments like compost, manures, cover crops, and organic fetilizers that are either plant or animal based. Seeds should be organic. Organic should have a buffer zone between what is organic and what is not. Even crops and plants sold in markets are required to be separated.
There are some synthetics that are allowed in organic culture
Some organic compounds have been banned like nicotine and rotenone because even though they are from organic sources, they can be very toxic to humans and animals.
Organic started out as a movement with the intent to protect the environment. Restore balance to depleted soils by supporting the soil web and decreasing dependence on synthetic fertilizers and the havoc that the misuse of synthetic fertilizers and other chemicals have had on the ecosytems of the world. It is not that synthetic fertilizers are inherently bad. Synthetic fertilizers and crop science as well as advances in technology have increased yields so that more food can be grown on less land and require fewer people engaged in agriculture. The negative effect of that has been urban sprawl. Concentrating animals into feed lots means there are more animals per acre and more animal poop to get rid of. Just because manure is organic, a ton of manure concentrated in a small area can still be a pollutant and run off when it rains and contaminate water ways and farms down stream. Homeowners and farmers alike, applied way to much fertilizer because they got great results, and figured more is better, right? Phosphates Tide and other detergents got clothes especially whiter, but the wastewater in many cities is dumped back into the same waterway that becomes someone else's drinking water down stream. The phosphate pollution and nitrogen runoff from high nitrogen fertilizers led to algae blooms in lakes, depleted oxygen and a lot of dead fish.
Phosphate contamination is so high and it takes years to correct, so that some states like Michigan have banned phosphate fertilizers to avoid adding to the problem.
Soil organisms and plants don't care where their food comes from. It can be organic or synthetic. Synthetic is ready to use for the plants, which is why crop yields were better and more could be grown on less land than with organic.
Organic is labor intensive requiring hundreds of pounds per acre, but considerably less synthetic for the same NPK.
The problem again is with disturbing the balance. While soil organisms consume the nitrogen from synthetic sources just fine, synthetics are not a balanced diet and the soil organisms need carbon too to remain healthy in the long run.
Whether you use synthetic or organic, it is possible to mess with nature too much and upset the balance. You can add too much manure or compost and that will change the pH or the soil nutrient holding capacity to a point where the soil becomes unhealthy. Like adding lime to everything, or fertilizing because someone said this or that product was good rather than actually looking at the health of the soil and only adding what was needed.
In a forest the soil is actually very poor. The trees are supported because they recyle the nutrients they remove by dropping leaves and fallen trees will decompose and return the nutrients back to the soil. Animals that live in the forest will leave their droppings from the leaves and fruit they ate and that also returns. In a closed system, if it in balance, it stays balanced.
Unfortunately, humans get in the way. They try to make things better for themselves by planting things they like, but that are not native to the area. They add stuff, some organic, some synthetic, often by the seat of their pants and it works for a few years because nature does try to compensate. But after a few years of harvesting the fruits, but not returning anything (first time gardeners who plant seeds without prepping or fertilizing, can usually get a good crop a year or two before the soil is too depleted to grow anything well.)
Some people add manures, leaves, fertilizer, synthetic and/or organic but they plant the same things year after year in the same place. They sometimes go a little longer, but if they have not replaced the nutrients removed in the right proportions or have gone overboard with some nutrients because they don't really check what their soil needs, they start having problems. If they have figured out an equitable formula, they can go on for years.
Monoculture in large farms is taking its toll. Yields are good, but nature is still unbalanced. Wild animals are displaced by houses that move into their neighborhood, and now they are the pests, because people have taken away their food supply, so now they start eating what the people have planted instead. Bees, birds, and other animals are disappearing due to habitat loss and competition/.conflicts with domestic animals for food.
Lastly, organics is supposed to be a method of improving the soil and recycling nutrients in a sustainable way.
1. The soil is not helped at all if you plant in pots, not in the soil
2. If you constantly have to feed a plant in a pot, even with organic fertilizer, it iss not sustainable, since constant inputs are required from outside. It is an open not closed system.
3 Many people believe that organics is healthier but the science says that there is no nutritional difference between an organic or conventionally grown plant. Under the same growing conditions, they will contain the same nutrients and calories. One is not healthier than the other
4. Organics does not use pesticides. Many people believe organic vegetables and fruits are grown without pesticides and taste better. I don't know if they taste better, but organic organizations keep harping on the pesticides used in conventional farming but do nothing to tell the truth about how much pesticides they use.
5. The FDA regulates food sold in markets and said that the food sold is safe, both conventional and organic.
6. Organic produce have no pesticide residues. Well, they shouldn't, the produce is only tested for conventional pesticides. I don't think they are testing them for oganic pesticide residues. I think they should.
7. Organic pesticides are toxic, they have to be, otherwise what good would it be. They just have to be applied more often, organic farmers are limited in what they are allowed to use, and they don't last as long.
8. Organics is sustainable. Well, maybe, maybe not. If you have have to continually add more inputs from outside the system, then it is not truly sustainable. If you are importing leaves, manure, feedstocks, and adding organic fertilizer year after year, the system is not a closed system and not sustainable.
9 Organic seed must be grown organically for a minimum of 3 years.
10 If you are strictly organic, all of our inputs must also be organic.