For the past few decades there has often been a lack of appreciation of why we need to preserve soils. During this period there have been numerous examples of damage to world soils, some of which are now irreparable. Some examples of the problems that face soils include:
Soil erosion and desertification: This is a major problem in many countries in the world, particularly, but not solely, in the drier, warmer parts of the world. Desertification currently affects about one-sixth of the world’s population and a quarter of the world’s land. Six to seven million acres are lost annually to soil erosion and both these processes continue to increase despite the many attempts made to introduce measures to stop or reduce erosion. It is a major threat to world soils and because of this there have been major initiatives to reduce desertification and erosion, including those by UNESCO, FAO, and the European and US Conservation bodies. However factors such as the need to increase food production and the likely impacts of global climate change are likely to make the fight against erosion and desertification increasingly difficult.
Salinisation and alkalisation: It is estimated that over 20 million hectares of land is affected by salinisation and alkalisation, again mainly the drier more arid areas of the world. Salts may be deposited in a number of ways; by winds coming in from the oceans, by use of irrigation with salt-containing water, and by salt accumulation in low-lying spots in the landscape as the climate varies. Like erosion and desertification, it is only in recent years that the problem has been recognised as a serious one and steps taken to reduce its spread. However, once accumulated in the soil it is a difficult and long-term problem to get rid of it.
Impact of intensive agriculture: The last four decades has seen a major increase in intensive agriculture in the bid to feed the world population more efficiently than ever before. In many countries, particularly the more developed countries, this intensification of agriculture has led to the use of more and heavier machinery, deforestation and clearing of land for use in cultivation. This has led to several problems including loss of organic matter, soil compaction and damage to soil physical properties generally, over-application of many nutrients in the form of fertilisers and pesticides, leading to problems with contamination of water supplies, potential loss of soil fauna and flora, such an essential part of a healthy soil, amongst others.
Urbanisation and land contamination: Urbanisation and the sealing of soils by infrastructures (i.e. building structures on top of soil) represents a significant loss of soil, particularly because the loss becomes more or less permanent. In developed countries there is a loss of about 1 per cent of land to urbanisation each decade.
The 18th and 19th centuries also saw enormous industrial expansion in many parts of the world with two major consequences for soils. Firstly, the widespread burning of fossil fuels in industry has led to widespread acidification of rainwater; for many decades soils of Western Europe have been leached by rainwater with a ph of about 4, i.e. strongly acidic. The second legacy of industry is contaminated land, the extent and effects of which are still not fully known.
Thus in the last few decades there have been many pressures put on global soils and already significant and irrecoverable damages have been done. We now need to move forward with much more awareness about the damage that has been caused to global soil resources and with a realistic programme for the preservation and protection of this unique natural entity, soil. Already there is increasing awareness of soil erosion and desertification in many countries and measures in place to protect soils from future damage. But in some environments, such as parts of Africa, the soil is a fragile entity, it lacks a robust nature, and therefore particular attention needs to be paid to its management and to ensuring that the management is clearly in tune with the soil. This is a real challenge but unless this challenge is accepted the route to future use of many of these soils could become a dead-end, with catastrophic results for many communities. Many of the techniques needing to be applied are already well known, the challenge will be to integrate them into land use practice, particularly in a likely changing climate.
The problems of salinisation and alkalisation continue and are reversible only with great difficulty. As with erosion and desertification, the causes are generally well established but very difficult and costly to remediate and solve. It is important that the problem does not continue to increase and there therefore needs to be better communication between the land user and those that advise them about their soils, and between policy makers and environmental scientists.
The problems associated with intensification of agriculture outlined above are more readily treatable. The causes of the problems are well established and already in many developed countries actions are being taken to work more in harmony with the soil. Some of the problems may take just a few years to improve upon whereas others, e.g., low contents of organic matter and nitrates moving downwards into groundwater, may take decades to remediate.
There need to be national and international plans for urbanisation that take into consideration the importance of protecting soils. Everyone is aware of the need to build more houses and to improve infrastructures but this process needs much more careful planning than before, with the need to preserve and protect soils in mind. Already we are much more aware of the problems of soil contamination and the difficulties that arise from 'post-industrial' use contaminated land. Many countries now have safeguards in place to help to prevent soil contamination. Clean up of the contaminated land, however, remains a problem both technically and financially.
Soils have suffered from several decades of damage on a scale that we must not allow to continue. The reasons for this neglect are many. But if we are to ensure the protection of global soils into the future there must be much stronger awareness and acceptability among the public, policy makers and land users of the need to preserve soils for current and future generations. To ensure that this takes place it will be important that World Organisations and National Governments ensure there are adequate measures in place to give a much needed emphasis on soils and their future protection.
"Treat the earth well: it was not given to you by your parents, it was loaned to you by your children. We do not inherit the Earth from our Ancestors, we borrow it from our Children."