Abstract Understanding the agroecological mechanisms that determine forage yield and quality in intensively managed permanent grasslands is crucial to optimize management and provide environmental and economic benefits to society. In this study, we assessed the relative contribution of climatic, soil and vegetation drivers on forage yield and quality in nine different frequently defoliated and fertilized permanent grasslands used for silage production, that were representative of diverse environmental conditions in Switzerland. Temperature and precipitation, forage yield and quality (i.e., fibers, lignin, carbohydrates, N, P and K contents), relative proportion of plant functional groups, as well as soil nutrient availability and moisture were measured in 2018 (a particularly dry year) during the first three growth cycles. Linear-mixed effect models were performed to test differences among growth cycles on all measured variables and the relationships among them for each cycle. Moreover, a multiple factor analysis (MFA) was performed for each growth cycle to investigate the complex relationships among different sets of variables. Overall, the growth cycle significantly affected all variables, except for forage P content that remained stable over time. Most of the variability in forage yield and quality was explained by climatic conditions and plant functional groups proportion with, however, differences among growth cycles. In the first growth cycle, forage yield and quality were mainly related to the proportion of grasses, precipitation and temperature, then by the proportion of grasses and temperature in the second growth cycle, and finally, by soil nitrogen availability, precipitation and proportion of grasses in the third growth cycle. Overall, in the range of the studied conditions, we found very limited impact of soil nutrient availability on forage yield and quality, except soil N availability during the third growth cycle. Our findings may help prioritize grassland management interventions at specific times during the growing season.

中文翻译：

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在集约化管理的永久性草地的前三个生长周期中，牧草产量和质量的气候、土壤和植被驱动因素各不相同

摘要 了解决定集约化管理的永久性草原牧草产量和质量的农业生态机制对于优化管理和为社会提供环境和经济效益至关重要。在这项研究中，我们评估了气候、土壤和植被驱动因素对 9 个用于青贮生产的经常落叶和施肥的永久性草地的牧草产量和质量的相对贡献，这些草地代表了瑞士不同的环境条件。2018 年（特别干旱的年份）测量了温度和降水、牧草产量和质量（即纤维、木质素、碳水化合物、N、P 和 K 含量）、植物功能组的相对比例以及土壤养分有效性和水分在前三个生长周期中。执行线性混合效应模型以测试所有测量变量的生长周期之间的差异以及每个周期的它们之间的关系。此外，对每个生长周期进行了多因素分析 (MFA)，以研究不同变量集之间的复杂关系。总体而言，生长周期对所有变量都有显着影响，但随着时间推移保持稳定的牧草磷含量除外。牧草产量和质量的大部分变化是由气候条件和植物功能组比例以及生长周期之间的差异来解释的。在第一个生长周期中，牧草产量和质量主要与草的比例、降水和温度有关，然后在第二个生长周期中与草的比例和温度有关，最后，由土壤氮的有效性、降水量和第三个生长周期中草的比例决定。总的来说，在研究条件的范围内，我们发现土壤养分有效性对牧草产量和质量的影响非常有限，除了第三个生长周期中的土壤氮有效性。我们的研究结果可能有助于在生长季节的特定时间优先考虑草地管理干预。