Land Degradation The pie chart below shows the main reasons why agricultural land becomes less productive. The table shows how these causes affected three regions of the world during the s. Summarize the in formation by selecting and reporting the main features, and make comparisons where relevant.
Neolithic Revolution Centres of originas numbered by Nikolai Vavilov in the s. Area 3 gray is no longer recognised as a centre of origin, and Papua New Guinea area P, orange was identified more recently.
Land degradation has accelerated during the 20th century due to increasing and combined pressures of agricultural and livestock production (over-cultivation, overgrazing, forest conversion), urbanization, deforestation, and extreme weather events such as droughts and coastal surges which salinate land. Deforestation to clear large tracts of land for agricultural production and grazing is often the initial cause of soil degradation. Estimated using satellite data, million km 2 of land was deforested between and , with the majority of this loss in the tropics (Hansen et al., ). Deforestation of unsuitable land Deforestation is both a type of degradation as such, and also a cause of other types, principally water erosion. Deforestation in itself is not necessarily degrading without it, most productive agricultural lands (in the temperate zone as well as the tropics) would not be available.
At least 11 separate regions of the Old and New World were involved as independent centers of origin. Rice was domesticated in China between 11, and 6, BC with earliest known cultivation from 5, BC,  followed by mungsoy and azuki beans.
Sheep were domesticated in Mesopotamia between 13, and 11, years ago. Sugarcane and some root vegetables were domesticated in New Guinea around 9, years ago.
Sorghum was domesticated in the Sahel region of Africa by 7, years ago. Cotton was domesticated in Peru by 5, years ago,  and was independently domesticated in Eurasia.
In Mesoamericawild teosinte was domesticated to maize by 6, years ago. Studies of the transition from hunter-gatherer to agricultural societies indicate an initial period of intensification and increasing sedentism ; examples are the Natufian culture in the Levantand the Early Chinese Neolithic in China.
Then, wild stands that had previously been harvested started to be planted, and gradually came to be domesticated. Ploughs appear in pictographs around 3, BC; seed-ploughs around 2, BC.
Farmers grew wheat, barley, vegetables such as lentils and onions, and fruits including dates, grapes, and figs. Farming started in the predynastic period at the end of the Paleolithic, after 10, BC.
Staple food crops were grains such as wheat and barley, alongside industrial crops such as flax and papyrus. Sheep and goats were kept mainly for dairy products.
The Mayas used extensive canal and raised field systems to farm swampland from BC.
The natives controlled fire on a regional scale to create a low-intensity fire ecology which sustained a low-density agriculture in loose rotation; a sort of "wild" permaculture. Sinceagriculture in the developed nations, and to a lesser extent in the developing world, has seen large rises in productivity as human labor has been replaced by mechanizationand assisted by synthetic fertilizerspesticides, and selective breeding.
The Haber-Bosch method allowed the synthesis of ammonium nitrate fertilizer on an industrial scale, greatly increasing crop yields and sustaining a further increase in global population.
Pastoralism involves managing domesticated animals. In nomadic pastoralismherds of livestock are moved from place to place in search of pasture, fodder, and water.
This type of farming is practised in arid and semi-arid regions of Sahara, Central Asia and some parts of India. The land is then used for growing crops for several years.
When the soil becomes less fertile, the area is then abandoned. Another patch of land is selected and the process is repeated. This type of farming is practiced mainly in areas with abundant rainfall where the forest regenerates quickly.
This type of farming is practiced mainly in highly developed countries. In recent years there has been a backlash against the environmental effects of conventional agriculture, resulting in the organicregenerativeand sustainable agriculture movements.Deforestation to clear large tracts of land for agricultural production and grazing is often the initial cause of soil degradation.
Estimated using satellite data, million km 2 of land was deforested between and , with the majority of this loss in the tropics (Hansen et al., ). Deforestation is accounted for 30% degradation of cultivable land while over-cultivation results 28% land degradation.
All other minor reasons are categorised as ‘other’ and constituted 7% loss of land fertility. Prices, Land Use and Deforestation: Evidence from the Tapajós Basin Arthur Bragançay CPI August Abstract This paper examines the impact of changes in agricultural land use on deforesta-.
Agricultural Land Degradation; Deforestation and Over-Cultivation Essay the effects of these causes on three regions over the period of s.
One of the more prominent takeaways of both charts is that more over -grazing than other factors had moderately negative impacts on the world land. Agriculture and Deforestation: Is REDD+ Rooted In Evidence? Author links open overlay panel Romain Pirard a Karine Belna b.
(Reducing Emissions from Deforestation and Degradation) might address agriculture expansion on forests. We study in the first place the Borlaug/land sparing hypothesis, according to which an increase in agricultural.
iii Foreword Land and water resources are the foundation for agricultural production, fisheries and aquaculture that provide nutrition and income to people, together with other products for food, fuel, fodder and building materials.