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LIU Lei-lei ZHU Yan LIU Xiao-jun CAO Wei-xing XU Mao WANG Xu-kui WANG En-li 《中国农业科学(英文版)》2014,(1):187-194
The accurate assessment of the spatiotemporal changes in soil nutrients influenced by agricultural production provides the basis for development of management strategies to maintain soil fertility and balance soil nutrients. In this paper, we combined spatial measurements from 2 157 soil samples and geostatistical analysis to assess the spatiotemporal changes in soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP) and available potassium content (AK) from the first soil survey (in the 1980s) to the second soil survey (in the 2000s) in the Taihu region of Jiangsu Province in China. The results showed that average soil nutrients in three soil types all exhibited the increased levels in the 2000s (except for AK in the yellow brown soil). The standard deviation of soil nutrient contents increased (except for TN in the paddy soil). Agricultural production in the 20 years led to increases in SOC, TN, AP and AK by 74, 82, 89 and 65%, respectively, of the Taihu areas analyzed. From the 1980s to 2000s all the nugget/sill ratios of soil nutrients indices were between 25 and 75% (except for AK in the yellow brown soil in the 2000s), indicating moderate spatial dependence. The ratio of AP in the yellow brown soil in the 2000s was 88.74%, showing weak spatial dependence. The spatial correlation range values for SOC, TN, AP and AK in the 2000s all decreased. The main areas showing declines in SOC, TN and AP were in the northwest. For AK, the main region with declining levels was in the east and middle of western areas. Apparently, the increase in soil nutrients in the Taihu region can be mainly attributed to the large increase in fertilizer inputs, change in crop systems and enhanced residues management since the 1980s. Future emphasis should be placed on avoiding excess fertilizer inputs and balancing the effects of the fertilizers in soils. 相似文献
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阿拉斯加州1990年有3家利用桦树液制造糖浆的企业,分散在阿拉斯加州的不同地方,但当时相互间并无关系。过了3年,阿州东南部又开办一家。以后每2年有一家糖浆厂投产。短短10年里,阿拉斯加州已经有7家桦汁糖浆厂。 相似文献
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美国:美国林务局太平洋西北部沿岸研究站3月12日公布的报告指出,2014年美国的华盛顿州、俄勒冈州、加利福尼亚州北部和阿拉斯加州的原木和锯材出口量均比2013年有所减少。2014年,西海岸的原木出口量为17.06亿板英尺,锯材出口量为8.92亿板英尺,分别比2013年减少了13%和14%。原木的出口总额为13.1亿美元,锯材的 相似文献
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1美国水资源现状及管理利用经验1.1美国水资源状况美国地处北美洲中部,总面积9.37×106km2,辽阔的地域上平原、山脉、丘陵、沙漠、湖泊、沼泽等各种地貌类型均有分布,境内地势东、西两侧高,中间低,东西以南北走向的落基山脉为界,是太平洋水系和大西洋水系的分水岭,两边自然和气 相似文献
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宋燕波 《绿色中国(综合版)》2006,(4):58-61
是否开放阿拉斯加州的战略石油储备基地,20多年来,美国国会每年都要就此展开一场激烈的争论。阿拉斯加被认为是美国最好的石油开发新地段,这个地区的石油储备是30到100亿桶,堪称“北极油罐”。对石油饥渴的美国而言,这无疑是块令人垂涎的肥肉。 相似文献
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