论述张掖市盐化灌漠土的分布、形成过程、特性及危害?
参考答案:
分布:主要分布在高台县骆驼城、南华,临泽县小屯等地。零星分布在山丹县清泉、东乐等地区。
形成过程:在灌耕熟化过程中受平原修建水库、高位水渠或灌溉不当等因素的作用,使地下水位抬高,埋藏深度小于2m。
特性:速效养分氮、磷含量低,土壤僵硬板结,通透性差,适耕期短。春秋返潮,盐分表聚,形成盐斑,地面盐斑占10-30%,有机质含量在10g/kg左右。
危害:土壤肥力低,影响作物出苗。种植小麦的产量只有150-200kg/亩。
论述张掖市盐化灌漠土的分布、形成过程、特性及危害?
参考答案:
分布:主要分布在高台县骆驼城、南华,临泽县小屯等地。零星分布在山丹县清泉、东乐等地区。
形成过程:在灌耕熟化过程中受平原修建水库、高位水渠或灌溉不当等因素的作用,使地下水位抬高,埋藏深度小于2m。
特性:速效养分氮、磷含量低,土壤僵硬板结,通透性差,适耕期短。春秋返潮,盐分表聚,形成盐斑,地面盐斑占10-30%,有机质含量在10g/kg左右。
危害:土壤肥力低,影响作物出苗。种植小麦的产量只有150-200kg/亩。
Air France SA said Monday that its second-quarter net profit fell 35 percent to 57 million ($57.4 million), but sales were steady and operating profit surged. Earnings before interest and tax, a measure of operating income, gained 86 percent to 141 million as fuel costs fell and cargo traffic rose. Air France has been hurt less than rivals such as British Airways PLC and Lufthansa AG by the slowdown on North Atlantic routes following the war on Iraq in 2003 because it has fewer flights in that market. Net income fell as the airline paid deferred taxes that came due. Sales rose 0.9 percent to 3.2 billion. The carrier lost about 80 million in revenue because of a four-day strike by pilots in September. An accord was reached tying future pay increases to inflation. The carrier said that first-half fuel costs fell 15 percent to 680 million. Cargo traffic rose 11 percent in the second quarter, while passenger traffic rose 1.1 percent. The airline’ s shares gained 87 cents, or 7.7 percent, to close at 12.11. Separately, Air France and Alitalia SpA agreed to buy 2 percent stakes in each other as Europe’s second-and sixth-largest airlines deepen their partnership. |