Intensive agriculture is the primary subsistence pattern of large-scale, populous societies. It results in much more food being produced per acre compared to other subsistence patterns. Beginning about 5,000 years ago, the development of intensive farming methods became necessary as the human population grew in some major river valleys to levels beyond the carrying capacity of the environment using horticulture and pastoralism. The transition to intensive agriculture was originally made possible by water management systems and the domestication of large animals for pulling plows. This allowed farmers to get below the top soil to bring buried nutrients up to the surface. It also allowed farmers to maintain much larger fields of crops.
Subsistence agriculture is performed by one family, typically. Enough food is generated for that one family to subsist or survive. This is different than agriculture practiced in western capitalist countries, wherein the product is economically profitable, and not just limited to an amount of food produced that allows one family to subsist.
Humid tropic conditions are found over nearly 50 per cent of the tropical land mass and 20 per cent of the earth's total land surface an area of about 3 billion hectares. Tropical Central and South America contain about 45 per cent of the world's humid tropics, Africa about 30 percent, and Asia about 25 per cent. As many as 62 countries are located partly or entirely within the humid tropics. Agricultural systems and techniques that have evolved from ancient times to meet the special environmental conditions of the humid tropics include the paddy rice of South-East Asia, terrace, mound, and drained field systems, raised bed systems (such as the chinampas of Mexico and Central
Cited: * Jorge, Niosi & Majlinda, Zhequ. “Aerospace Clusters: Local or Global Knowledge Spillovers?” March 2005. <http://www.findarticles.com>. * Virgin, Bill. “Global Economy Complicates Outsourcing.” Seattlepi.com. 24 January 2006. <http://www.seattlepi.nwsource.com/business>. * Lee, Dwight R. "Comparative Advantage Continued" The Freeman: Ideas on Liberty - October 1999. http://www.fee.org/publications/the-freeman/article.asp?aid=4962. * Wikipedia. <http://en.wikipedia.org/wiki/Outsourcing * Fellmann, Getis, Getis. Human Geography: Landscapes of Human Activities. 2003. * Wikipedia. <http://en.wikipedia.org/wiki/forestry