Abstract：
Agricultural practices enhancing soil organic carbon (SOC) show potential to buffer negative effects of climate change on forage grass performance. We tested this by subjecting five forage grass varieties differing in fodder quality and drought/flooding resistance to increased persistence in summer precipitation regimes (PR) across sandy and sandy-loam soils from either permanent (high SOC) or temporary grasslands (low SOC) in adjacent parcels. Over the course of two consecutive summers, monoculture mesocosms were subjected to rainy/dry weather alternation either every 3 days or every 30 days, whilst keeping total precipitation equal. Increased PR persistence induced species-specific drought damage and productivity declines. Soils from permanent grasslands with elevated SOC buffered plant quality, but buffering effects of SOC on drought damage, nutrient availability and yield differed between texture classes. In the more persistent PR, Festuca arundinacea FERMINA was the most productive species but had the lowest quality under both ample water supply and mild soil drought, whilst under the most intense soil droughts, Festulolium FESTILO maintained the highest yields. The hybrid Lolium × boucheanum kunth MELCOMBI had intermediate productivity and both Lolium perenne varieties showed the lowest yields under soil drought, but the highest forage quality (especially the tetraploid variety MELFORCE). Performance varied with plant maturity stage and across seasons/years and was driven by altered water and nutrient availability and related nitrogen nutrition among species during drought and upon rewetting. Moreover, whilst permanent grassland soils showed the most consistent positive effects on plant performance, their available water capacity also declined under increased PR persistence. We conclude that permanent grassland soils with historically elevated SOC likely buffer negative effects of increasing summer weather persistence on forage grass performance, but may also be more sensitive to degradation under climate change.
摘要：
提高土壤有机碳（SOC）的农业实践显示出缓冲气候变化对牧草性能的负面影响的潜力。我们通过使五种饲料质量和抗旱/抗洪性不同的牧草品种在永久性（高SOC）或临时草地（低SOC）的沙质和沙质壤土中夏季降水方案（PR）的持久性增加来进行测试。相邻地块。在连续两个夏天的过程中，单文化中观每3天或每30天经历多雨/干旱天气交替，同时保持总降水量相等。PR持久性的增加会导致特定物种的干旱破坏和生产力下降。来自永久性草地的土壤，具有较高的SOC缓冲植物质量，但是SOC对干旱损害的缓冲作用，质地类别之间的养分利用率和产量不同。在更持久的公关中，高羊茅是生产力最高的物种，但在充足的供水和轻度土壤干旱下质量最低。在最严重的土壤干旱下，雌二醇FESTILO保持了最高的产量。黑麦草×boucheanumkunthMELCOMBI杂种生产力中等，而黑麦草品种在土壤干旱下的产量最低。但牧草品质最高(尤其是四倍体品种MELFORCE)。性能随植物成熟期和季节/年份的变化而变化，并且是由干旱和再湿润期间物种之间水和养分利用率以及相关氮营养的变化所驱动的。此外，虽然永久性草地土壤对植物性能表现出最一致的积极影响，在PR持久性增加的情况下，它们的可用水容量也有所下降。我们得出的结论是，历史上SOC升高的永久性草原土壤可能会缓冲夏季天气持久性增加对牧草性能的负面影响，但也可能对气候变化下的退化更敏感。
