Crop rotation is thought to reduce weed density and maintain species diversity, preventing the domination of few competitive weeds. In this work rotations of 1, 2, 4 and 6 years length have been compared in a long-term experiment since 1976. In order to detect the effect of rotation length and fertilization on weed community evolution, a specific study was performed on weed seedbank with soil sampling in 1993 and 2012.

Results

show that weed density was not affected by rotation length or fertilization type or rate, and that about 98% of weed species were indifferent to the factors applied. The dominance of Portulaca oleracea and increment of a few grass weeds were consequences of an inadequate management of late emergence and post-harvest weeds. Furthermore, no significant changes in the distribution of seeds longevity groups occurred in the seedbank from 1993 to 2012. In cropping systems where herbicides are used according to best practices or to Integrated Weed Management principles, the effect of rotation on weeds is hard to detect even in long-term experiments. For this, the effect of herbicides must be included in a more general theory of rotational effects.

中文翻译：

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20年轮作及不同施肥策略对杂草种子库的影响

作物轮作被认为可以减少杂草密度并保持物种多样性，防止少数竞争性杂草占优势。在这项工作中，自 1976 年以来的长期实验中比较了 1、2、4 和 6 年的轮作长度。为了检测轮作长度和施肥对杂草群落进化的影响，对杂草种子库进行了具体研究在 1993 年和 2012 年进行了土壤采样。

结果

表明杂草密度不受轮作长度或施肥类型或施肥率的影响，并且大约 98% 的杂草种类对所施加的因素无动于衷。马齿苋的优势地位和一些禾本科杂草的增加是晚出苗和收获后杂草管理不当的结果。此外，从 1993 年到 2012 年，种子库中种子长寿群体的分布没有发生显着变化。在根据最佳实践或综合杂草管理原则使用除草剂的种植系统中，轮作对杂草的影响甚至难以察觉在长期的实验中。为此，除草剂的作用必须包含在更普遍的轮作效应理论中。