Cover crops are grown between two main crops to reduce periods of bare fallow. In highly diverse crop rotations, the lengths of break periods between two main crops vary highly over time and consequently the cover cropping management differs from year to year. Long‐term field trials are thus of limited use because the same cover cropping approach only appears once in several years. This increases the need to better determine the immediate effects of different cover cropping strategies on soil properties. This study evaluated two cover cropping strategies and monitored the temporal development of several soil properties on six fields in Eastern Switzerland in the 9 months period between harvest of winter wheat and sowing of spring crops. The two tested strategies were (a) double cover cropping (DCC) where two cover crops mixtures were grown subsequently and shallowly (3 cm) incorporated into the topsoil and (b) permanent soil cover (PSC) with one grass‐clover mixture, which was harvested and thus not incorporated into the soil. Soil samples at three different soil depths (0–5, 5–10 and 10–20 cm) were sampled four times in high spatial resolution and analysed using a combined approach of visible near infrared spectroscopy and conventional lab methods. Differences between the sampling times and field sites were stronger than effects of different treatments. For soil organic carbon (SOC), no significant difference was measured between treatments in 0–20 cm soil depth. Only when analysed per depth segment, the PSC treatment showed significantly higher SOC increase in 5–10 cm soil depth than the DCC treatment. This could be due to the longer soil cover and thereby associated longer root growth period in the PSC treatment, leading to higher below ground C inputs than in the DCC treatment. On the other hand, the DCC treatment showed generally higher increases in permanganate oxidizable carbon stocks (0–5 cm), microbial C (0–10 cm), microbial N (0–10 cm) and mineral N (0–10 cm) than the PSC treatment. We conclude that maximizing cover crop above ground biomass input by planting two cover crops (DCC) benefitted soil microorganisms on most fields but was less beneficial on SOC than permanent soil cover (PSC) in 5–10 cm soil depth.

中文翻译：

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有机减耕系统中的覆盖作物：最大限度地提高土壤覆盖率还是植物地上生物量投入？


覆盖作物种植在两种主要作物之间，以减少裸露休耕期。在高度多样化的作物轮作中，两种主要作物之间的休息期长度随着时间的推移变化很大，因此覆盖作物管理每年都不同。因此，长期的田间试验用途有限，因为相同的覆盖作物方法几年才出现一次。这增加了更好地确定不同覆盖作物策略对土壤特性的直接影响的需求。本研究评估了两种覆盖作物策略，并监测了瑞士东部六块田地在冬小麦收获和春季作物播种之间的 9 个月内几种土壤特性的时间发展。两种测试策略是 （a） 双覆盖作物 （DCC），随后种植两种覆盖作物混合物，并浅 （3 cm） 掺入表土中，以及 （b） 永久土壤覆盖 （PSC） 与一种草-三叶草混合物，该混合物被收获，因此未掺入土壤。以高空间分辨率对三种不同土壤深度（0-5、5-10 和 10-20 cm）的土壤样品进行了四次采样，并使用可见光近红外光谱和传统实验室方法的组合方法进行了分析。采样时间和野外地点之间的差异强于不同处理的效果。对于土壤有机碳 （SOC），在 0-20 cm 土壤深度内，处理间没有显着差异。仅在按深度段分析时，PSC 处理显示 5-10 cm 土壤深度的 SOC 增加显著高于 DCC 处理。 这可能是由于 PSC 处理中的土壤覆盖较长，因此根系生长期较长，导致地下 C 输入高于 DCC 处理。另一方面，DCC 处理显示高锰酸盐可氧化碳储量 （0-5 cm）、微生物 C （0-10 cm）、微生物 N （0-10 cm） 和矿物 N （0-10 cm） 的增加通常高于 PSC 处理。我们得出的结论是，通过种植两种覆盖作物 （DCC） 最大限度地提高覆盖作物的地上生物量输入对大多数田地的土壤微生物有益，但对 SOC 的益处不如 5-10 厘米土壤深度的永久土壤覆盖 （PSC）。