Sub- theme - IV Anthropogenic activities on land

Sub-theme - IV
Anthropogenic activities on land
There is a sufficiency in the world for man's need but not for man's greed.
~Mohandas K. Gandhi


Anthropogenic (Greek word, meaning manmade) effects, processes or materials are those which are derived from human activities. Since all agricultural activities are directly or indirectly, affected by how the “soil is handled”, its health becomes the prime concern before one can address human and livestock health issues. Managing soil is a formidable challenge to ensure productivity, profitability and national food security. Soil quality can be assessed by a number of physical, chemical and biological attributes / processes. Relevance of one or more unfavourable soils conditions for long periods leads to un-sustainability of agricultural system. Major effects of anthropogenic activities on land resources are summarized below:
Land degradation: Land degradation, defined as lowering and losing of soil functions, is becoming more and more serious worldwide in recent days, and poses a threat to agricultural production and terrestrial ecosystem. Land degradation includes loss of top soil, physical changes like damage of soil structure (compaction), chemical changes like salinization, sodification, acidification, deposition of heavy metals and an overall declination of fertility and productivity of soil. It is estimated that nearly 2 billion ha of soil resources in the world have been degraded which includes approximately 22% of the total cropland, pasture, forest, and woodland. Though climatic and geogenic processes are major driving forces for land degradation, the impact of anthropogenic factors can not be overruled particularly when local situations are taken into consideration. Among the anthropogenic processes, agriculture, industrialization and urbanization all contribute significantly.
Agricultural activities like tillage disintegrates soil structure, causes organic matter depletion encourages soil erosion and nutrient loss. However, tillage practices improve soil air and modify temperatures for seed germinations and microbial activities. Heavy traffic load of tillage implements causes soil compaction. Over irrigation and application of poor quality of irrigation water lead to problems like water logging and soil salinization. Injudicious application of chemical fertilizers of nitrogen and phosphorus fertilizers and the concentration of livestock and their manures within small areas, have not only causes chemical degradation of agricultural land but also substantially increased the pollution of surface water by runoff and groundwater by leaching of excess nitrogen (as nitrate). Other agricultural chemicals like herbicides and pesticides causes contamination of surface as well as ground water.
The industrial wastes contribute largely to the chemical degradation of the valuable land resources. Improper waste management renders the surrounding areas vulnerable to heavy metal deposition in soil, water bodies, rivers as well as ground water. Rapid urbanization also aggravates the problem of land degradation still further.
Severe erosion of the productive top soil through wind and water action is aggravated by intensive mining, deforestation, improper range land management as well as injudicious tillage practices in agricultural fields. Besides that a sizeable amount of loss of top has been has been attributed to brick making and pottery affecting the livelihood of many traditional communities. It is important to note that it takes centuries to replenish 2.5 cm of top soil.
Loss of biodiversity: Biodiversity refers to totality of genes, species, and ecosystems of a region. India at present has 2.4% of land area of the world but contributes 8% species to global diversity. The Western Ghat, the Himalayas and the Indo-Burma regions are among the thirty four Hotspots identified worldwide as regards to vulnerable biodiversity resources. Biodiversity loss is a common phenomenon associated with land use and land cover change. When a natural forest land is transformed to farm land, the loss of tree species along with numerous associated flora, fauna and micro organisms is immediate and complete. Similarly, increasing grazing pressure on unmanaged pasture and rangelands causes severe damage to the biodiversity. Furthermore, the market driven intensive cropping system with overuse of chemicals leaves the agricultural biodiversity under severe threat. Even the so called eco- friendly technology of energy consumption like adaptation of bio-fuel when injudiciously followed has added tremendous pressure to the natural biodiversity of through dramatic shift in the land use pattern.
Green house gas load to atmosphere: Atmosphere is the mirror to our abuse to land resources. Every anthropogenic activity of concern to the precious land resources leaves an imprint in the atmosphere. There has been global ecological concern for increased concentration of carbon dioxide by 31%, methane by 151% and nitrous oxide by 17 % since 1750 which is incidentally coincided with the pace of land use change enforced by industrial revolution, urbanization, large scale live stock farming and by also modernization of agriculture. This has direct and indirect link with climate change and the problems associated with it. Though geological forces are assumed have big impact on increasing concentration of green house gases in the atmosphere, the human intervention can go a long way to ameliorate the adverse impact of increased GHG concentration. The soil-plant-animal system is an effective source of the important green house gases to the atmosphere. An efficient management of this system through judicious land use planning can increase the buffering capacity of the land resource.
Water contamination: Water is an important component of our land resource. The water which sustains the human life in the planet may become a source of diseases and a root cause of calamities if contaminated chemically or biologically. The quality as well as quantity of available water resource is regulated to a great extent by anthropogenic activities like industrialization, urbanization as well as by crop and livestock farming through unscientific disposal of solid and liquid wastes. The concentrations of heavy metals like, arsenic, lead, chromium etc in drinking water are in pockets due to a combination of geological and anthropogenic reasons. On the other hand a huge amount of harmful organic and synthetic effluents are leached to the surface and ground and surface water as farm land and urban wastes. The interrelation of water pollution with land use change must be analyzed for detailed understanding.
Hydrology: The hydrology refers to the study of water dynamics in surface and subsurface system. The natural catchments of watersheds are disturbed through rampant expansion of settlement areas. The technological intervention has made unimaginable geomorphologic changes possible at a faster rate. The large water bodies and hill tops are not spared. Even the natural river paths are modified by under man made projects. The rate of infiltration is impaired by rigorous anthropogenic activities enhancing the surface run off loss after each rainfall event. This has aggravated the water logging and flash flood in many urban and semi urban areas. On the other hand the ground water recharge is severely affected. This coupled with overexploitation of ground water to meet the demand from agriculture, industry and human settlement has made the situation worse day by day.
Although many of these problems are not solely from anthropogenic activities, these are certainly being aggravated by human activities. More over, it is the responsibility of every human being to sustain the land resources for the future generation through judicious land use planning. Nature is the school where the young minds are to be educated through participatory science activities.