<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Richter, Daniel deB.</style></author><author><style face="normal" font="default" size="100%">Hofmockel, Michael</style></author><author><style face="normal" font="default" size="100%">Callaham, M. A.</style></author><author><style face="normal" font="default" size="100%">Powlson,D. S.</style></author><author><style face="normal" font="default" size="100%">Smith,P.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Long-Term Soil Experiments: Keys to Managing Earth's Rapidly Changing Ecosystems</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Science Society of America Journal</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><volume><style face="normal" font="default" size="100%">71</style></volume><pages><style face="normal" font="default" size="100%">266-279</style></pages><abstract><style face="normal" font="default" size="100%">To meet economic and environmental demands for about 10 billion people by the mid-21st&lt;br /&gt;
century, humanity will be challenged to double food production from the Earth’s soil and&lt;br /&gt;
diminish adverse effects of soil management on the wider environment. To meet these challenges,&lt;br /&gt;
an array of scientifi c approaches is being used to increase understanding of long-term&lt;br /&gt;
soil trends and soil–environment interactions. One of these approaches, that of long-term&lt;br /&gt;
soil experiments (LTSEs), provides direct observations of soil change and functioning across&lt;br /&gt;
time scales of decades, data critical for biological, biogeochemical, and environmental assessments&lt;br /&gt;
of sustainability; for predictions of soil productivity and soil–environment interactions;&lt;br /&gt;
and for developing models at a wide range of scales. Although LTSEs take years to&lt;br /&gt;
mature, are vulnerable to loss, and have yet to be comprehensively inventoried or networked,&lt;br /&gt;
LTSEs address a number of contemporary issues and yield data of special signifi cance to soil&lt;br /&gt;
management. The objective of this study was to evaluate how LTSEs address three questions&lt;br /&gt;
that fundamentally challenge modern society: how soils can sustain a doubling of food&lt;br /&gt;
production in the coming decades, how soils interact with the global C cycle, and how soil&lt;br /&gt;
management can establish greater control over nutrient cycling. Results demonstrate how&lt;br /&gt;
LTSEs produce signifi cant data and perspectives for all three questions. Results also suggest&lt;br /&gt;
the need for a review of the state of our long-term soil-research base and the establishment of&lt;br /&gt;
an effi ciently run network of LTSEs aimed at soil-management sustainability and improving&lt;br /&gt;
management control over C and nutrient cycling.
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