The reduction of chemical inputs in agriculture is a current challenge. Perennial forage legumes such as lucerne produce protein-rich forage without synthetic nitrogen fertilizers but the crops may be invaded by weeds. Association of legumes with grasses are recognized to lower weed pressure but may alter forage yield and quality. Pure lucerne was compared to lucerne-grass mixtures, with the test of grass species differing for morphological, phenological and quality traits. The grass species were compared in mixture with lucerne for their performance, which was evaluated through weed occurrence, forage yield and quality. Seven perennial grass species were evaluated in association with lucerne and compared to pure lucerne and pure grass (one species only), in field plot experiments in two locations, without nitrogen fertilisation. Forage yield, botanical composition (lucerne, grass, weeds), protein and acid detergent fibre were measured in four cuts per year during three years. Treatments were compared, and mixture model effects such as direct and associated effects of the grass on dry matter yield of the species in the associations were calculated. Lucerne-grass association reduced weed development compared to pure lucerne. The protein content was slightly lower in the associations than in pure lucerne but the association generally produced more protein per hectare than expected if the two species were grown in separated plots (i.e. protein overyielding). Depending on the grass species, the weed control, the forage quality, the proportion of lucerne and the dry matter yield of the association were differently affected. Species, with a small direct effect (on grass production) and a large associated effect (on lucerne production), such as timothy and meadow fescue, favoured lucerne proportion in the associations. Association of grass species with lucerne is a way to limit weed occurrence while maintaining protein content and forage yield in the association. These traits, as well as the lucerne proportion in the association, varied depending on the grass species. At a practical level, the application of herbicides on lucerne crops could be significantly lowered, and this with a limited impact on forage yield and quality. From a scientific point of view, the calculation of mixture model effects is of interest to analyse the outcome of species associations.

中文翻译：

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苜蓿-草群落中七种草的杂草控制、蛋白质和饲料产量

减少农业化学投入是当前的挑战。苜蓿等多年生饲料豆科植物无需合成氮肥即可生产富含蛋白质的饲料，但农作物可能会受到杂草的侵袭。豆类与禾本科植物的结合被认为可以降低杂草压力，但可能会改变饲料产量和质量。将纯苜蓿与苜蓿草混合物进行比较，测试不同草种的形态、物候和品质特征。将草种与苜蓿混合后的性能进行比较，通过杂草发生情况、饲料产量和质量进行评估。在两个地点的田间试验中，对七种多年生草类与苜蓿进行了评估，并与纯苜蓿和纯草（仅一种）进行了比较，没有施氮肥。三年内每年进行四次切割，测量草料产量、植物成分（苜蓿、青草、杂草）、蛋白质和酸性洗涤纤维。比较处理，并计算混合模型效应，例如草对关联中物种干物质产量的直接效应和相关效应。与纯苜蓿相比，苜蓿-草组合减少了杂草的生长。联合体中的蛋白质含量略低于纯苜蓿，但如果两个物种生长在不同的地块中，联合体每公顷产生的蛋白质通常比预期的要多（即蛋白质产量过高）。根据草种的不同，草丛的杂草防治、饲草品质、苜蓿比例和干物质产量受到不同程度的影响。直接影响较小（对牧草生产）和关联影响较大（对苜蓿生产）的物种，如梯牧草和草甸羊茅，在关联中优先考虑苜蓿比例。草种与苜蓿的关联是限制杂草发生同时保持关联中蛋白质含量和饲料产量的一种方法。这些特征以及关联中苜蓿的比例因草种而异。在实际操作中，可以显着减少苜蓿作物上除草剂的使用量，这对牧草产量和品质的影响有限。从科学的角度来看，混合模型效应的计算对于分析物种关联的结果很有意义。