Winter catch crops are grown to scavenge nutrients over a period of unfavorable growth conditions and to conserve nutrients for subsequent release to the following main crop. Since environmental conditions have a strong impact on the growth and nutrient capture in roots and shoots of individual catch crop species, we anticipated that mixtures will be more durable and efficient in nutrient capture due to compensatory effects among component species. We tested this hypothesis and determined the nitrogen and phosphorus accumulation in the shoots and roots of four catch crop species grown in pure vs. mixed stands at two sites for two or three years. Element concentrations were determined in the root and shoot biomass of each species and used to calculate the nutrient pool fixed in the root or shoot biomass. A qPCR-based technique was applied to quantify the root biomass of individual species based on species-specific DNA sequences. Despite considerable variation across environments, the overall plant biomass of white mustard (Sinapis alba), lacy phacelia (Phacelia tanacetifolia) and bristle oat (Avena strigosa) was similar and higher than that of Egyptian clover (Trifolium alexandrinum). While pure stands varied 6- to 24-fold in shoot biomass depending on environmental conditions, the variation was only ~3-fold for catch crop mixtures, with less pronounced variation in the root biomass. In general, the root biomass was comparable to the shoot biomass in each species. Roots contributed 26–46% of the nitrogen and 36–48% of the phosphorus to the total accumulation of these nutrients in the catch crop biomass, thus emphasizing the importance of plant roots as belowground nutrient pool for potential carry-over of nutrients to the subsequent crop. Although the mixture was mostly dominated by two of the four species, namely mustard and phacelia, it captured similar or even larger amounts of nutrients than the best-performing pure stand under any growth condition. This was the case for shoot- and for root-bound nutrients. Our results indicate that catch crop mixtures have higher durability than pure cultures to environmental variations. The amount of nitrogen captured by the mixture meets the average postharvest nitrogen that is left over by a wide range of cash crops, thus emphasizing that catch crop mixtures represent an efficient nutrient management tool in crop rotations.

种植冬季捕捞作物是为了在不利的生长条件下清除养分，并保存养分以供随后释放到下一个主要作物。由于环境条件对单个捕获作物物种的根和芽的生长和养分捕获有很大影响，我们预计由于成分物种之间的补偿作用，混合物在养分捕获方面将更加持久和有效。我们检验了这一假设，并确定了在两个地点的纯林与混合林中种植的四种捕捞作物物种的芽和根中氮和磷的积累两到三年。在每个物种的根和茎生物量中确定元素浓度，并用于计算固定在根或茎生物量中的营养库。基于物种特异性 DNA 序列，应用基于 qPCR 的技术来量化单个物种的根生物量。尽管环境之间存在相当大的差异，但白芥的总植物生物量（Sinapis alba )、花边 phacelia ( Phacelia tanacetifolia ) 和猪鬃燕麦 ( Avena strigosa ) 与埃及三叶草 ( Trifolium alexandrinum ) 相似且更高）。虽然根据环境条件，纯林分的枝条生物量变化 6 至 24 倍，但捕获作物混合物的变化仅为约 3 倍，根生物量的变化不太明显。一般来说，每个物种的根生物量与枝条生物量相当。根系贡献了 26-46% 的氮和 36-48% 的磷，这些养分在捕获作物生物量中的总积累，因此强调了植物根系作为地下养分库的重要性，因为它有可能将养分带入后续作物。尽管该混合物主要由四种物种中的两种，即芥菜和 phacelia 为主，但在任何生长条件下，与表现最佳的纯林相比，它捕获的养分相似甚至更多。枝条和根系养分就是这种情况。我们的结果表明，捕获作物混合物比纯培养物对环境变化具有更高的耐久性。混合物捕获的氮量满足各种经济作物剩余的平均收获后氮量，因此强调捕获作物混合物代表了作物轮作中的有效养分管理工具。