Organically managed fields are highly attractive for wild animals of open agricultural landscapes because of a high percentage of green covered fields; for example, by green manures, catch crops and underseeds. Forage legumes are the main source of nitrogen in organic farming. Forage legumes are also important habitats for wild animals. The main ecological disadvantage is frequent mowing of forage crops. Increasing the time without disturbance in favour of wild animals may also decrease crop productivity and increase weed pressure. Here, we studied the effect of modified mulching dates on yield, nitrogen fixation and weed colonisation of lucerne green manure under pannonian site conditions during two vegetation periods in Eastern Austria. We compared a natural treatment, where the first mulching took place two weeks earlier and the second mulching two weeks later than in a conventional treatment with the latter. While in the first year the shoot dry-matter yield (−1.5 t ha⁻¹), nitrogen yield and the amount of fixed nitrogen (−44 kg N ha⁻¹) in lucerne were significantly lower in the natural than in the conventional treatment at the first cut, no differences could be detected in the second year. The seasonal amount of nitrogen fixation as well as the percentage of N derived from the atmosphere (N_dfa) at both cuts did not differ between the treatments. The natural treatment also had no disadvantageous effects on weed coverage. Our results show that prolonging the period without disturbance in lucerne crops had no adverse agronomic effects with only one exception: the 14-day shorter development period in the natural treatment at the first cut decreased shoot yield and nitrogen fixation compared with the conventional treatment in the first year, when weather conditions were humid before the first cut and dry afterwards. We therefore recommend shifting mulching dates and prolonging cutting intervals in lucerne on organic farms under pannonian site conditions in favour of wild animals.

中文翻译：

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自然保护地覆盖期对绿肥苜蓿作物产量和固氮的影响

有机管理的田地对开放农业景观的野生动物极具吸引力，因为绿色田地的比例很高。例如，通过绿肥，收割庄稼和种子。饲草豆科植物是有机农业中氮的主要来源。饲草豆科植物也是野生动物的重要栖息地。主要的生态劣势是草料作物的频繁修剪。增加对野生动物有利的无干扰时间也可能会降低作物的生产力并增加杂草压力。在这里，我们研究了改良的覆盖日期对奥地利东部两个植被时期潘诺期定点条件下卢塞恩绿肥的产量，固氮和杂草定居的影响。我们比较了自然疗法，第一次覆盖的时间比常规处理的早两周，第二次覆盖的时间晚了两周。在第一年，茎干杂物产量（−1.5 t公顷^第一次采伐时，自然条件下自然生成的紫苏中的氮素产量和固定氮含量（−44 kg N ha ^-1）显着低于常规处理（^-1），第二年没有发现差异。固氮的季节数量以及大气中氮的含量（N _dfa）两次切割之间的差异在处理之间没有差异。天然处理对杂草覆盖率也没有不利影响。我们的研究结果表明，延长卢塞恩农作物的无干扰期没有任何不利的农艺效应，只有一个例外：与常规处理相比，第一次采伐时自然处理的第14天缩短了14天的发育期，降低了芽的产量和固氮能力。第一年，天气条件在第一次切割前潮湿，然后干燥。因此，我们建议在Pannonian场地条件下，在有机农场中改变覆盖日期并延长卢塞恩的切割间隔，以利于野生动物。