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一、问题的提出 桃源县位于湖南省的西北部,东经110°50′36″到111°36′32″, 北纬28°24′30″到29°24′13″之间,是洞庭湖平原向湘西山地过渡的地带。全县总面积为4441.22平方公里。耕地面积为139.56万亩,其中稻田104.69万亩。全县总人口91.5046万人,其中农业人口85.0209万人。人平耕地面积1.6亩,其中稻田1.3亩,人平山林4.6亩,其中人平荒山1.2亩。 该县属于中亚热带向北亚热带过渡的季风湿润气候,气候条件极其复杂。年平均气温为12～16.5℃,无霜期260～309天,≥0℃积温为4100～6100℃,≥10℃积温为3400～5200℃;年日照时数为1250～1550小时;年降水量1350～2200毫米,年平均相对湿
First, the issue put forward Taoyuan County is located in the northwestern Hunan Province, longitude 110 ° 50’36 “to 111 ° 36’32”, latitude 28 ° 24’30 “to 29 ° 24’13”, is the Dongting Lake plain Xiangxi mountain transition zone. The total area of 4441.22 square kilometers. Cultivated land area is 139.56 million mu, of which 104.69 mu is paddy field. The county’s total population of 915046 people, of which agricultural population 85020900 people. The average cultivated area is 1.6 mu, of which 1.3 mu is paddy field, 4.6 mu is Pingren Mountain, and 1.2 mu is Pingren Mountain. The county belongs to the monsoon humid climate of the transition from the subtropical north to the subtropics, and the climatic conditions are extremely complicated. The average annual temperature is 12 ~ 16.5 ℃, the frost-free period is 260 ~ 309 days, the accumulated temperature is ≥ 4100 ~ 6100 ℃, the ≥10 ℃ accumulated temperature is 3400 ~ 5200 ℃, the annual sunshine duration is 1250 ~ 1550 hours, the annual precipitation is 1350 ~ 2200 mm, annual average relative humidity