Due to the soil erosion, nutrient depletion, loss of soil organic carbon, soil sealing and other threats, the world’s soils are rapidly deteriorating. Around 33 percent of agricultural lands are moderately or highly degraded, poses big challenge to global food security. But, this trend can be reversed by promoting sustainable management practices and the use of appropriate technologies, according to a new UN report released in Rome today.
The Status of the World’s Soil Resources produced by FAO’s Intergovernmental Technical Panel on Soils brings together the work of some 200 soil scientists from 60 countries. Its publication coincides with World Soil Day which is celebrated on 4 December and also the end of the UN International Year of Soils 2015 an initiative which has served to raise global awareness on what has been described as ‘humanity’s silent ally’.
"Let us promote sustainable soil management rooted in proper soil governance and sound investments. Together, we can promote the cause of soils, a truly solid ground for life," UN Secretary-General Ban Ki-moon said in a message for World Soil Day.
Soils are vital for producing nutritious crops and they filter and clean tens of thousands of cubic kilometres of water each year. As a major storehouse for carbon, soils also help regulate emissions of carbon dioxide and other greenhouse gases, thus fundamental for regulating climate.
Yet, the overwhelming conclusion of the report is that the majority of the world’s soil resources are in only fair, poor or very poor condition and that conditions are getting worse in far more cases than they are improving. In particular, 33 percent of land is moderately to highly degraded due to erosion, salinisation, compaction, acidification, and chemical pollution of soils.
"Further loss of productive soils would severely damage food production and food security, amplify food-price volatility, and potentially plunge millions of people into hunger and poverty. But the report also offers evidence that this loss of soil resources and functions can be avoided," said FAO Director-General José Graziano da Silva.
The impact of population growth, urbanisation and climate change
Changes to the condition of soils are primarily driven by population growth and economic growth, factors that are expected to persist in the decades to come.
The report notes how to feed a global population that has grown to some 7.3 billion today, over 35 percent of the Earth’s ice-free land area has been converted to agriculture. The result is that soils that have been cleared of natural vegetation to grow crops or graze livestock suffer from sharp increases in erosion and steep losses in soil carbon, nutrients and soil biodiversity.
But urbanisation is also taking a major toll. The rapid growth of cities and industries has degraded increasingly wide areas, including by contaminating soils with excess salt, acidity and heavy metals; compacting them under heavy machinery; and sealing them permanently under asphalt and concrete.
Achieving healthy soils
The report focuses on the 10 main threats to soil functions: soil erosion, soil organic carbon loss, nutrient imbalance, soil acidification, soil contamination, waterlogging, soil compaction, soil sealing, salinisation and loss of soil biodiversity.
It notes how there is a general consensus on soil-related strategies that can, on the one hand, increase the supply of food, while on the other, minimise harmful environmental impacts.
The solution proposed is one that centres on sustainable soil management and which requires the participation of a broad level of stakeholders ranging from governments to small-holder farmers.
Erosion, for example, can be curbed by reducing or eliminating tillage – digging, stirring, and overturning of soil – and using crop residues to protect the soil surface from the effects of rain and winds. Similarly, soils suffering from nutrient deficits can be restored and yields increased by returning crop residues and other organic material to the soil, employing crop rotation with nitrogen-fixing crops, and making judicious use of organic and mineral fertilisers.