How Much Can You Safely Take Out From the Land?

One thing that we are not short of in our society is experts, and it would be supposed that amongst all the university professors and government scientists there would exist a considerable body of knowledge relating to how much produce it is safe to take from a particular area of ground before it starts to suffer a loss of fertility. However, if this knowledge does exist, it has never been put in the public domain.
This may be because modern farming has evolved in such a way that its proponents do not fully acknowledge the concept of soil fertility at all: agricultural science treats a field as though it is composed of more-or-less inert matter, a soil analysis is conducted, and nutrients are added in the quantities and proportions required for a particular crop. Once the crop reaches maturity, one hundred per cent of the harvested material can be sold to the food-processing industry, and, in theory, the land is left no worse than at the beginning. One problem with this technique is that it leaves the farmer completely at the mercy of the global agro-chemical and agricultural-equipment industry – they have to have a modern tractor, modern equipment, and prairie-like fields in order to be part of the system, and they then have to use the latest crop varieties (possibly genetically modified), and the latest chemical formulations, backed up by expensive agricultural consultants, in order to operate. If they are lucky, the price they are paid for their produce will offset all these costs, and compensate them for their work, but they have no personal control over whether or not their farms are profitable, or how they manage them.
An even more significant problem faces the consumer, who, by purchasing a food products, may find themselves financing industries of which they do not approve, and which may even be having a direct, or indirect negative impact upon their health
For a growing number of people, the answer is to buy organic, and to support small-scale producers: but then they come back to the question of how much produce can safely be removed from a farm before fertility is reduced.
This is not a trick question (i.e. the answer isn’t nothing). Nature is able to capture the sun’s energy, and convert it into vegetable matter, simply using the basic ingredients of water, air and minerals which plants can extract from the ground. If everything is consumed locally, then the land becomes richer and richer in organic matter and minerals, its fertility increases, and it produces more crops. The most important element of soil fertility is derived from the presence of organic matter which is a source of food for soil-based organisms – fungae, bacteria and insects. These organisms help to aerate the soil, making it possible for plant roots to thrive, and helping in water retention. They also provide a food source for animals higher up the food chain, i.e. a sizable proportion of the produce produced on a self-sustaining farm goes to feed wildlife, and the presence of wildlife is both an indicator of fertile soil, and an essential element in maintaining soil fertility.
When working a piece of land, the amount of wildlife that you see can be taken as a guide to whether or not you are taking too much away. If the area of land is small, you cannot expect to see an immediate rise in the number of large mammals and birds – the process starts with small insects, and worms that you see when you are working the ground. If your land is surrounded by large, industrially-farmed fields, then it might always be difficult for larger creatures to survive, but Nature is very resourceful, and over time, a stable eco-system will be established, the soil will become richer, small birds will restrict their territories to the area of your land, frogs and toads will start to appear, there will be lizards, and snakes, bumble bees, butterflys, voles, and small mammals.
The more fertile a piece of land becomes, the more that can be taken from it – but there is no short cut; bringing in fertilisers and chemicals from outside, might boost the crop, but does not help the soil organisms, and the task of restoring soil fertility is simply put off till another day.