|
 |
 |
|
Terrace Cultivation Asia: Despite examples of the sensible conservation of land - such as reclamation in The Netherlands [3] and terrace cultivation Asia cultivation in Asia - agricultural areas elsewhere were often mismanaged on a vast scale. Overuse of land in the western prairies of the USA broke up a stable ecosystem so that during a period of drought and high winds in the 1930s the topsoil was removed and a dust bowl created. In other areas thoughtless removal of vegetation allowed heavy erosion of hilly areas -rainwater carved deep gullies and carried good topsoil into rivers, causing further problems through silting.
The wild ancestor of rice has been identified as Orysa sativa, a semiaquatic marsh grass, native to India and tropical southeast Asia. In addition some wild varieties of this species have been reported from tropical Africa. Wild wheat and barley were native to elevated dry lands ai Asia Minor, hence they could not be s^rown in marshy or even in tropical lowlands. Where tie cultivation of rice began is not known, but India seems the most probable place. The oldest civilizations known in India are in the northeast where semiarid lands were favorable to wheat and barley, traces of which appear in the ruins of cities at least 4,000 years old, but no traces of rice have been observed.
Cultivation. Cultivation is an ancient vineyard practice. It destroys weeds and facilitates other vineyard operations such as irrigation. Contrary to common belief, cultivation does not conserve soil moisture; however, the resulting destruction of weeds does conserve moisture. Discs or chisel-tooth cultivators are used, although some vineyards are still plowed. Heavy disc harrows are used to turn under weeds and cover crops. Weeds have been and are sometimes controlled with oil sprays or chemicals, usually diuron or monuron. |
|
|
| |
|
|
|
|
