Land degradation threatens food security
By MD. ASADULLAH KHAN
8 June 2013 (The Daily Star) – With two centuries of an unprecedented population boom, likely to reach 9 billion by 2050, land degradation by human activities and climatic upheavals poses a threat to food security, especially in a land-scarce country like Bangladesh. Historically known, it took the human species about 150,000 years to reach the 1 billion mark around 1800. Since then an additional 6 billion (!) have been added to the headcount — reaching 7 billion in 2011. In such a grim scenario, it is apparent that soil, like water has become a fundamental resource but it is being degraded. The process of soil degradation can take different forms: hydraulic erosion, wind erosion, changes in the soil’s composition and physical degradation. Most people in our part of the world do not know that over 50% of the land that has been degraded by deforestation are situated in Asia and 15% are in South America and. At the same time, 37% of the soils are degraded by inappropriate agricultural practices in Asia. According to Lester Brown, founder president of the World Watch Institute, a third of all cultivated land is losing its arable layers faster than it is gaining and this lessens its productivity. Using pesticides and chemical fertilisers destroys soil fauna; necessary for aerating soil. The well-known consequence of this phenomenon is runoff which causes floods and mudslides. Irrigation and soil drainage can cause acidification and salinisation whilst the use of chemical fertiliser and pesticides contributes to reducing soil capillarity (runoff) as well as its consistency. Soil provides living things with food, fibre and fuel. Since late 1940s to early 1990s, over 90% of the degradation of productive land was due to deforestation, overgrazing and inappropriate agricultural practices. Food & Agriculture Organisation (FAO) estimates that the world lost 94 million hectares in the last century. The land is under greater pressure in Bangladesh where a population of 160 million crowds into a 65,000 km of land area. Land holdings have shrunk and are now typically divided leaving only a scant share among the heirs. As the country’s population has exploded, the land has been subdivided so many times that the share per family is not enough to feed a family of five. Much of the world’s land is too rocky or arid or salty for agriculture. And forests that haven’t already been cut deserve protection: they harbour the habitats of earth’s endangered wild life. According to Washington-based World Watch Institute, the average amount of grain land per person in 30 years has dropped from 0.2 hectare to 0.1 hectare. Happily, a boom in agricultural productivity contributed by HYV variety of seeds, fertiliser and pesticide has kept the burgeoning population fed. While wars have always been fought over territory, the future may see green wars triggered by degradation and shortages of such basic resources as topsoil and water. The consequence has been the mounting pressure on woodlands, especially tropical forests that are the reservoirs of the majority of earth’s animal and plant species. According to FAO, 100,000 sq.km of tropical forest is lost every year. It is worth noting that great bulk of forest destruction has taken place since World War II, hence coinciding with the massive acceleration of economic development within the Third World countries. In Bangladesh, the massive assault on the Sundarbans, Madhupur forest, forest lands of Sylhet and Chittagong has invited drought, and desertification process of the already fragile land. Top soil loss is manifested in the deterioration of soil surfaces by erosive forces, especially water, wind, glacier, etc. Erosion also degrades soil’s structure and diminishes its water holding capacity — the greatest damage to the soil comes from water and wind erosion. Water erosion affects 25% of land in Bangladesh. Accelerated soil erosion has been encountered in the hilly regions of the country, which occupy about 1.7 million hectares. Bangladesh Agricultural Research Institute (BARI) recorded soil loss of 2.0 to 4.7 ton per hectare per year in different parts here. This soil loss manifests depletion of significant amount plant nutrients from the top layer causing a tremendous soil degradation. Where 25% of any country should be forest land, Bangladesh has now only 9%.As a region loses its forest, it loses its ability to trap and absorb water, and so run off from denuded woodland worsens the natural process of soil erosion. If at the same time farmers harvest the crop year after year, the soil is constantly exposed to wind and water. Studies from Indiana and Illinois have shown that in badly eroded areas an estimated 24% of their inherent initial productivity for corn is lost. Most importantly, intact soils ‘DO’ store a great deal of carbon — about 45 times more than is stored in all plants — and so they are very important in terms of global carbon budget functioning largely as a net sink for carbon dioxide. [more]
