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(一)我场地处东经104°29′,北纬35°45′,为黄土丘陵沟壑区。海拔高1800—2000米。土地属灰钙土类,干燥贫瘠,有机质含量低,酸碱度7.8～8.9,理化性质不良。年平均气温6.7℃,一月份平均气温8.0℃,七月份平均气温19.4℃,极端最高气温35.6℃,极端最低气温-24.4℃,平均年较差53.5℃;平均年降水量仅有390.0毫米,主要集中在七、八、九三个月,占全年降水总量的58％,多呈暴雨形式。冬春干旱,两季降水只占全年降水
(A) The site is located at 104 ° 29 ’east longitude and 35 ° 45 ° north latitude for the loess hill gully area. 1800-2000 meters above sea level. The soil belongs to the category of calcareous soil, dry and poor, with low organic matter content, pH 7.8 ~ 8.9, and poor physical and chemical properties. The annual average temperature is 6.7 ℃. The average temperature in January is 8.0 ℃. The average temperature in July is 19.4 ℃. The extreme maximum temperature is 35.6 ℃. The extreme minimum temperature is -24.4 ℃. The average annual temperature is 53.5 ℃. The average annual precipitation is only 390.0 mm. Concentrated in seven, eight, nine three months, accounting for 58% of the total annual rainfall, mostly in the form of heavy rain. Winter and spring drought, precipitation in the two seasons only annual precipitation