Context

Cover crops are sown in autumn after harvest of a main crop to capture residual nitrogen and to build biomass that will contribute to soil organic matter after being ploughed under. Mixtures are purportedly more productive than pure stands of single species.

Research problem

Dry matter accumulation in field crops can be separated in the processes of resource capture and resource conversion. Here we apply this conceptual approach to analyse whether and how pure stands of single species and stands of species mixtures differ in radiation capture and radiation use efficiency.

Methods

cover crops were sown as pure stands (12 treatments) or mixtures (11 treatments) at two years in four sites, three in the Netherlands and one in northern Germany. Ground cover was measured throughout a growing period of up to twelve weeks to quantify radiation capture while final biomass was determined at harvest. The ratio of biomass and cumulative radiation capture was used to calculate radiation use efficiency.

Results

Oats and crucifers were the most productive species. Crucifers covered the soil quickly and their radiation capture was consequently high (517 MJ m⁻²) but their radiation use efficiency was low (0.80 g MJ^-1). Oats intercepted less radiation (459 MJ m⁻²) than crucifers but had a higher radiation use efficiency (1.15 g MJ^-1). Legumes had low radiation interception (332 MJ m⁻²) combined with low radiation use efficiency (0.64 MJ m⁻²) while the group of forb species belonging to other plant families (e.g. Linaceae, Boraginaceae and Asteraceae) had intermediate radiation capture (371 MJ m⁻²) and radiation use efficiency (0.84 g MJ^-1). The radiation capture and radiation use efficiency of mixtures was similar to that of the dominant species in the mixtures, in all cases a crucifer or oats.

Conclusions and implications

The analysis of radiation capture and radiation use efficiency in this study indicates that mixture performance was governed by species dominance within the mixture, with the species capturing most of the light determining to a large extent the radiation use efficiency of the mixture as a whole. Results show the importance of including one or more productive species in a species mixture used for cover cropping, i.e. oats or a crucifer. If species with slow initial growth or low radiation use efficiency are included in a mixture to provide particular services, such as flower resources, atmospheric nitrogen fixation or antibiosis against pests, these species should be included in a large enough proportion to enable their establishment in the mixture.

中文翻译：

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冬季覆盖作物混合物的辐射截获和辐射利用效率

语境

在收获主季作物后的秋季播种覆盖作物，以捕获残留的氮并建立生物量，将其耕种后有助于土壤有机质。据称混合物比单一物种的纯林更有生产力。

研究问题

大田作物中干物质的积累可以在资源捕获和资源转化过程中分离。在这里，我们采用这种概念性方法来分析单一物种的纯林分和物种混合物的林分在辐射捕获和辐射利用效率方面是否以及如何不同。

方法

在两年中，在四个地点播种了纯作物（12种处理）或混合种植（11种处理），其中三个在荷兰，一个在德国北部。在长达十二周的整个生长期对地面覆盖物进行测量，以量化辐射捕获量，同时在收获时确定最终生物量。使用生物量与累积辐射捕获量之比来计算辐射利用效率。

结果

燕麦和十字花科植物是生产力最高的物种。十字花科植物很快覆盖了土壤，因此其辐射捕获率很高（517 MJ m ^-2），但辐射利用效率却很低（0.80 g MJ ^-1）。燕麦比十字花科植物截获的辐射少（459 MJ m ^-2），但辐射利用效率更高（1.15 g MJ ^-1）。豆科植物的辐射截获率低（332 MJ m ^-2），辐射利用效率低（0.64 MJ m ^-2），而其他植物科（如亚麻科，香菜科和菊科）的forb物种则具有中等的辐射捕获率（371） MJ m ^-2）和辐射利用效率（0.84 g MJ ^-1）。混合物的辐射捕获和辐射利用效率与所有情况下的十字花科植物或燕麦的混合物中的优势种相似。

结论与启示

这项研究中对辐射捕获和辐射利用效率的分析表明，混合物的性能受混合物内物质的支配性支配，而捕获大部分光的物质在很大程度上决定了混合物整体的辐射利用效率。结果表明，在用于遮盖作物的物种混合物（即燕麦或十字花科植物）中包括一种或多种生产性物种的重要性。如果混合物中包括初始生长缓慢或辐射利用效率低的物种，以提供特定服务，例如花卉资源，大气固氮或害虫抗生，则应以足够大的比例包括这些物种，以使其能够在植物体内建立。混合物。