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published on 3 December 2006 in life

Sustainable agriculture

Eating in order to survive
Agriculture is man’s main activity, it enables the production of food, that passes through shops and supermarkets, and reaches our tables. If agriculture did not exist, probably our species would not be there any more or it would not be the one it is today, i.e. the most influential on the planet.
Before inventing agriculture, man mostly hunted and gathered food. His existence instead of being based on settlements and the tendency to live in the same place for long periods of time, depended on incessant shifting from one place to another in order to continuously find new sources of food. In fact up to 10,000 years ago, food was not produced by means of agriculture, as it is today, but it was searched for and gathered in the midst of the numerous resources that the environment offered spontaneously. Nomadic tribes fed on edible products available in the wild, such as roots, fruits, leaves, berries, seeds, eggs and small animals, furthermore they fed on game,  such as the large ungulates.
This very active existence was simply the consequence of a fundamental need, which is easy to guess, and does not need many explanations : they ate in order to survive.

Agriculture in history
Men passed from being nomadic to a different life-style in which they began to settle down in fixed places with the advent of the so-called agricultural revolution, in which some populations remitted the spontaneous resources offered by nature and formed the first economies based on exploitation of the land. Many scholars believe that in the history of humanity this transition phase started over 10,000 years ago in a precise region, the “fertile crescent”, a strip of land in which numerous rivers flowed between Palestine, Iraq, Syria and Turkey.
Various hypotheses have been made about how the cultivation of plants  originated in this area of the Middle East, one of the most widespread states that chance played a key role. It is highly probable that some Mediterranean population in the Neolithic Age discovered, by pure coincidence that in some spots where seeds of an edible wild plant were dropped, as for example  a cereal, plants of the same type could be regenerated.
From this point to the awareness of the potentiality of the seeds probably did not take much time. Soon our ancestors realized that planting the seeds of the edible plants, it was possible to obtain plants with the same characteristics, and at times  with even better characteristics.
It must also be considered that more or less at the same time as these first forms of cultivation, also the first attempts at breeding animals were made. This aspect is often neglected, but actually when speaking of an agricultural revolution, reference is also made to the first steps in the process of domesticating animals. The result was a progressive and radical change in the system of life of humans and their way of interacting with nature.

The “green revolution”
A very important factor, favoured by the advent of agriculture, was the increase in the human population. Before discovering the agricultural properties of plants, in fact, the entire population world wide amounted to around 5 million people. After this discovery the number began to grow exorbitantly, it is calculated that at the beginning of the Christian era, human beings had increased 50 times, reaching 250 millions. In the meantime the cultivation of plants had spread to Africa, Asia and Europe and subsequently also to the New World.
And at that stage the first environmental effects due to this new source of food supply started to become evident. Wherever possible, in fact, the natural environments were transformed, in order to cultivate edible plants or to breed cattle, so land was subtracted from the wild animals and plants. Many regions around the world were deforested, desertified or however transfigured compared to the original characteristics of their territory, and this had a fallout on the appearance of the landscape and on the evolution of biodiversity.
However, for a long period of time the environmental alterations produced by the agricultural activities remained circumscribed to the cultivated territories, in the sense that the technologies and methods used for cultivation were mostly on a local scale and therefore so were their effects.
Approximately 50 years ago, however, the situation started to change and agriculture became one of the human activities that were most harmful for nature, with effects that slowly began to show a significance that spread beyond the local sphere. This change coincided with the time in which in developed countries agriculture was seen as a sector for development that was very promising also from an industrial point of view. For a second time there was a transition that was such that the term “revolution” was justified: the Green Revolution.
A sustainable agriculture?
Therefore, around the middle of the last century, the old agricultural activity, based on the cultivation of local products and manual labour of the farmers, gave way to a more technological agriculture, tied to industrial processes. Machinery has become essential for toiling the land and these have replaced human labour and animal driven power. Furthermore the variety of plants with a high yield have taken the place of numerous varieties that were once cultivated, determining a conspicuous increase in agricultural production, and at the same time  a very high cost from the point of view of the environment.
High-yield plants in fact require much more irrigation water than the traditional ones, and furthermore, they depend greatly on the application of large amounts of pesticides and fertilizers, and finally, they require a much deeper tilling of the soil.

Damages provoked by pesticides
Pesticides are toxic substances and they are often highly mobile. In other words their presence does not remain circumscribed in the cultivated fields, but spreads over much vaster areas. Many of these substances are transported by agriculture waste waters, and flow into rivers, lakes and seas. Some pesticides, furthermore, can filter deep into the soil and finally can contaminate the water table,  thus decreasing the quality of drinking water.
Human health is endangered by the use of pesticides not only because these contaminate the  vegetable foods and the animals we eat, but also because they may be found in the water we drink.
To this we must add the detrimental effects of the pesticides on biodiversity because  these are not only toxic for the parasites they are used to fight, but they  are also harmful for most  biological systems. This is because pesticides are unable to distinguish  between a harmful parasite and an organism that is helpful to agriculture, as for example any pollinating animal. Many of these substances are defined as “xenobiotic” by the scientists. This is because being totally unknown by the natural processes of the ecosystems they cannot be removed from the environment by natural chemical degradation carried out by micro-organisms (xeno = different, biotic = living).
These compounds also give rise to a phenomenon known as “bioaccumulation” which reflects their tendency to penetrate into organisms and accumulate in their tissues as they climb higher in the levels of the food chain. For this reason, a pesticide which, due to the washing away of the soil, or due to an agricultural drain flows into a body of water ( a river or a lake), can enter the food chain in the water and finally reach the human organism, for example through fish that is eaten.
Due to their xenobiotic characteristics and their power to bioaccumulate, pesticides are also very persistent in the environment. DDT, a well known pesticide that was widely used in agriculture after World War II, was prohibited after the 70s in all developed countries due to its high level of toxicity in man and all other animals. Notwithstanding this, even 30 years later, its presence is still noted in egg shells and in the tissues of numerous animal species, specially those living in close contact with water.

Fertilizers and eutrophication
In the past 40 years, use of synthetic fertilizers which  contain the main  nutrients of plants, i.e. nitrogen (N) and phosphorus (P), has increased almost eight times. However the data indicate that this growth is at least partly unjustified. In fact about half of the fertilizers that are applied to cultures nowadays, instead of being absorbed in the tissues of the cultivated plants,  flow into the subterranean and superficial waters.
The fact is negative because, this not only indicates that when using  the fertilizers something doesn’t work correctly, but also that this produces environmental deterioration. If a large percentage of the fertilizers is dispersed in the environment, in fact, two types of damage are produced in one time. The first type of damage is  economic  and is tied to the fact that an enormous quantity of fertilizers, and therefore of money, are wasted uselessly. The second type of damage instead is environmental. In fact these compounds must be considered full-fledged pollutants because once they penetrate the surface water they cause alterations in the chemical and biological composition. The problem is that once these flow into a river, a lake or into the sea, they continue to carry out their task, in other words to bring nourishment to the plants.
Bodies of water are inhabited by many types of algae (water plants). These, finding a large number of nutrients available, increase  their biological mass (biomass) enormously, causing the so-called algae-explosions. And when the vegetable biomass dies, it is decomposed by micro-organisms in the water through chemical reactions that modify the proportions of the dissolved gases. In practice,  most of the oxygen available in the water is consumed and therefore the possibility of breathing decreases for all the aquatic organisms and consequently they die.
At this stage large numbers of animals, plants and micro-organisms die.  The type of water pollution underlying this biological decay,  is known as “eutrophization”. Even though at times it can depend on other factors, in most cases eutrophization is provoked  by an excess of fertilizers used in agriculture.

Genetically modified plants
A much more recent development of industrial agriculture – such that some have classified this as the Second Green Revolution, concerns the so-called genetically modified plants (GM). A GM plant is a vegetable species in which DNA fragments from other plants have been introduced, or even from organisms belonging to different biological kingdoms, using special laboratory techniques based on genetic recombination. The large seed companies that produce and sell GM plants believe that these innovative techniques enable an improvement of the cultures that is much greater that what can be obtained with traditional selective techniques. Practically these guarantee bigger cultivations because the manipulation of their DNA increases their capacity to resist  the attacks of parasites and pesticides.
We will not add further details about this agriculture, defined “biotechnological”,  because in Europe there still is a heated discussion  regarding its efficacy. Some of its promises are very interesting, however with regard to its real sustainability, doubts have been expressed by many scientists, due to the risks it involves for the environment and for people’s health.

Agriculture and consumptions
Another cost imposed by the transformation of agriculture into an industrial activity is tied to the life-style of some of the world’s populations. In the rich countries in fact, 70% of the production of cereals is used  to feed livestock. All these animals, that are reared in batteries mainly to obtain meat and other products, aggravate the problem of environmental contamination of agricultural origin : intensive animal breeding farms are highly polluting and contribute to the eutrophization of surface waters.
It must also be said that if an increasingly large amount of the grains cultivated on a world scale are used for rearing livestock for the production of meat, in the future there may be a strong unbalance in the international cereal markets and in the distribution, across the planet, of food resources with a further worsening in the already difficult situation in the Third World countries. If the rich countries continue to consume the same quantity per capita of meat, that they consume today, in fact, people living in the poor countries will have increasingly less cereals available (rice, wheat and maize) in order to feed themselves, because the prices will rise.
In fact by allocating a larger amount of cereals to the animals on farms, there are less cereals for direct consumption by people, because the quantity of cereals that can be produced on a world scale has already reached its maximum level..
Furthermore it must be borne in mind that the world population has exceeded six billion units and will not stop increasing for at least 50 more years.
The consumption of meat in fact involves an indirect cereal consumption of cereals. But this cereal consumption is much more intense than direct consumption, because for every kilo of meat that is eaten (for example of beef) actually over 15 kg of cereals have been consumed.
As it can therefore be seen, to cultivate cereals in order to feed animals from which meat is obtained  is not the correct way for agriculture to become a fulcrum of sustainability.

An approach toward sustainability
The concept of sustainable agriculture is very recent, and from certain points of view it is also very difficult to apply. The first requirement that is necessary in order to carry out a veritable sustainable agriculture is a good awareness of the territory and its resources, but also of the cultural traditions of the people who live there, which is not always a simple operation.
In fact it must be clear that the word “sustainability”, in agriculture, means planning and carrying out  work on the land so that its aims and methods do not clash with the specific characteristics of the environment, but rather, that they  both move in the same direction. For example if, in a determined territory, the conditions of the soil, the climate and the biodiversity make it easier and more promising to cultivate fruit trees, rather than cereals, then privilege must be given to the former, that will not involve high costs and will guarantee a good harvest, rather than  invest in the latter, which instead will imply expensive treatments without promising the same results.
The meaning of sustainable agriculture then becomes slightly clearer and can be summarized in the rule that in order to cultivate in an intelligent manner it is necessary to gather the greatest contribution from nature and the least from man. Expressing the same concept with different words, it can be said that to obtain a well balanced agriculture, costs must be minimized (environmental, economic, social, etc), and the yields and conservation of the environment must be maximized.
From theory to practice
From a practical point of view, the primary interest of a farmer should be to guarantee the fertility of his land for a long period of time, which should be as long as possible. For this aim, some agricultural practices have proved to be very useful,  as for example very light forms of  ploughing and tilling the soil.
In some cases it has been noted that in the cultivated fields the constant presence of a light covering of plants can guarantee a good texture of the soil due to the good gripping effect produced by the roots. In other cases it was proved that  fertility is favoured by cyclic crop rotation with other crops that increase the supply of nutrients in the ground, improving its chemical properties in terms of pH, minerals and organic substances. All these aspects are important and  enable  farmers to decrease the need for chemical fertilizers and other external contributions.
Furthermore many studies have pointed out that recourse to chemical pesticides can be decreased, and in some cases, even be eliminated by carrying out a correct biological battle. This latter technique is based on the principle that many parasites in agricultural cultivations can be fought  in such a way that the appropriate conditions for their predators to settle are created  in the fields, as for example many species of insects and  spiders, and their pathogens, as some bacteria and fungi that are not dangerous for man. In order to obtain these results, however, it is indispensable to  carry out long term investments in biodiversity.   Let us try to clarify this last point. Investment in long term biodiversity means that the first step to reach an sustainable agriculture must be carried out by the farmers who must make the effort to generate, on their farms, small non-cultivated strips of land in which plants and animals of various types can live (shrubs, hedges, trees, insects and other invertebrates, birds, micromammifers, reptiles, etc.). Even though these do not contribute to the profits, these small  strips of land offer enormous  ecologic gains in exchange, (and indirectly also economic ones) because they enable the circulation of many biological species that are “friends” of agriculture. In practice it means favouring, in the cultivated areas, the conditions of biological wealth that are useful to  maintain fertility of the ground for long periods of time, a control of the parasites, protection from the wind, from the rain and erosion, in addition to an entire series of other properties that are typical of sustainable agriculture.
These interventions need some more sacrifice in the beginning, but after a short amount of time they ensure greater stability of the land that is cultivated and greater safety for the farmers and for the production of food.

Written by Carlo Modonesi

With the sponsorship of the Italian Ministry of Education, Universities and Research
 
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