• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Fifty years of agricultural soil change in Iowa.
【24h】

Fifty years of agricultural soil change in Iowa.

机译：爱荷华州五十年来农业土壤的变化。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Many scientists have studied agricultural soil change. Most of these studies focus on changes in the surface 0 to 30 cm soil. Despite a whole body of scientific research that shows that soils change on relatively short time scales under different management regimes, classical pedological theory states that we should expect these changes to occur only in the surface few centimeters and that they are not of adequate magnitude to suggest fundamental changes in pedon character over short periods of time. Nevertheless, when we resampled sites that were initially described by the soil survey between 1943 and 1963 and compared current and historical descriptions and laboratory data, we found fundamental changes---often to more than 100 cm depth in one or more of the following---soil color, texture, structure, depth to carbonates, depth to redoximorphic features, bulk density, organic matter content, and pH. These sites have been under predominantly row-crop agriculture during that time and are located in Iowa, United States. In the surface 0 to 45 cm of soil, we found degradation of soil structure, loss of organic matter, lower cation exchange capacity and lower pH. When we look at the whole soil profile (sampled to 150 cm) the story becomes more complete and interesting. For example, organic C is moving deeper in the soil profile. This results in modern pedons that have an overall accumulation of organic C relative to their originally sampled counterparts, even though epipedons today contain less organic C than they did in 1959. Likewise, grey redoximorphic features are found deeper in the profile. This reveals a deepening of the water table, suggesting a statewide lowering of base level. Overall, anthropedogenesis accelerates melanization, erosion, cumulization, oxidation and braunification, while dissolving and translocating carbonates and organic matter and altering soil structure. From the changes in soil properties we also (1) document changes in classification and (2) estimate erosion rates. First, in each of three taxonomic systems, the classification of 60% or more of the sampled pedons was different from the original in at least one level of the hierarchies. Fifteen to 32% of sampled pedons changed at the Order (or equivalent) level with 11% to 33% of the pedons originally classified as Black Soils---Mollisols, Chernozems or Phaeozems---no longer classified as Black Soils. Second, we estimate actual erosion rates on our sites to be two to three times the tolerable rate. Given our sampling protocol on relatively low stable slopes, we surmise that average rates across all of Iowa--and indeed much of the Corn Belt--should, in fact, be higher, potentially much higher.
机译：许多科学家研究了农业土壤的变化。这些研究大多集中在0至30厘米土壤表层的变化上。尽管有大量的科学研究表明，土壤在不同的管理制度下会在相对较短的时间内发生变化，但经典的土壤学理论指出，我们应该期望这些变化仅发生在几厘米的表面上，并且它们的变化幅度不足以表明脚印特性在短时间内发生根本性变化。不过，当我们对1943年至1963年间土壤调查最初描述的地点进行重新采样并比较当前和历史描述以及实验室数据时，我们发现了根本的变化-在以下一项或多项工作中，深度通常超过100厘米- -土壤的颜色，质地，结构，碳酸盐深度，氧化还原形态深度，堆积密度，有机质含量和pH值。这些时期主要位于美国爱荷华州的行作农作物中。在0至45厘米的土壤表面，我们发现土壤结构退化，有机物流失，阳离子交换能力降低，pH降低。当我们查看整个土壤剖面（采样到150厘米）时，故事变得更加完整和有趣。例如，有机碳在土壤剖面中的移动越来越深。这导致现代花ped相对于原始采样的花ped具有整体的有机C积累，即使今天的花ped含有比1959年少的有机C。同样，在轮廓中发现灰色氧化还原形态特征。这揭示了地下水位的加深，表明全州基准水位降低。总体而言，人类发生会加速黑色素化，侵蚀，累积，氧化和褐化，同时溶解和转移碳酸盐和有机质并改变土壤结构。根据土壤性质的变化，我们还（1）记录分类的变化，（2）估算侵蚀速率。首先，在三个分类系统中的每个分类系统中，至少有60个等级的抽样脚架的分类在至少一个层次上不同于原始分类。有15％至32％的脚踏板在定级（或同等水平）上发生了变化，其中最初有11％至33％的脚踏板被归类为黑土-软体动物，黑钙土或辉石-已不再归类为黑土。其次，我们估计站点上的实际侵蚀率是可忍受率的两到三倍。鉴于我们在相对较低的稳定坡度上的采样方案，我们推测爱荷华州乃至整个玉米带的平均速率实际上应该更高，甚至可能更高。

著录项

  • 作者

    Veenstra, Jessica Jeanne.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Agriculture Soil Science.;Environmental Sciences.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 73 p.
  • 总页数 73
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号