Natural and planted grasslands play a very important role in agriculture as source of various ecosystem services, including carbon sequestration and biodiversity, and are responsible for a large fraction of agricultural water use in rainfed and irrigated fields. It is, therefore, relevant to precisely know their water use and vegetation requirements with consideration of relevant climate, from extremely cold, dry, with long winter seasons, to tropical humid and hot climates, thus with a large variability of vegetation. Semi-natural grasslands are basically used for grazing and mainly refer to highland pastures and meadows, steppes, savannas, pampas, and mixed forest systems. The FAO method to compute crop (vegetation) evapotranspiration (ET_c) through the product of a crop coefficient (K_c) by the reference evapotranspiration (ET_o) is adopted. The selected papers were those where actual ET_c (ET_{c act}) was derived from field observations and ET_o was computed with the FAO56 definition, or with another method that could be referred to the former. Field derived ET_{c act} methods included soil water balance, Bowen ratio and eddy covariance measurements, as well as remote sensing vegetation indices or surface energy balance models, thus reviewed K_{c act} (ET_{c act}/ET_o) values were obtained from field data. These K_{c act} refer to initial, mid-season and end season (K_{c act ini}, K_{c act mid}, K_{c act end}) when reported values were daily or monthly; otherwise, only average values (K_{c act avg}) were collected. For cases relative to cold or freezing winters, data refer to the warm season only. For grasses cut for hay, K_{c act ini}, K_{c act mid}, and K_{c act end} refer to a cut cycle. K_{c act} values rarely exceeded 1.25, thus indicating that field measurements reported did respect the available energy for evaporation. Overall, K_{c act mid} for semi-natural grasslands in cold climates were lower than those in hot climates except when available water was high, with K_{c act mid} for meadows and mountain pastures generally high. Steppes have K_{c act mid} values lower than savannas. Grasses commonly planted for hay and for landscape generally showed high K_{c act mid} values, while a larger variability was observed with grasses for grazing. The collected K_{c act} values were used to define standard K_c values for all grassland and grasses. Nevertheless, the tabulated K_{c act} are indicative values of K_c to be used for actual water management purposes and/or irrigation scheduling of planted grasslands. It is expected that a better knowledge of the standard and/or indicative K_c values for a wide variety of grasslands and grasses will support better management aimed to improve grass productivity and ecosystem services, including biodiversity and carbon sequestration.

天然和人工草地作为各种生态系统服务的来源在农业中发挥着非常重要的作用，包括碳固存和生物多样性，并且在雨养和灌溉领域占农业用水的很大一部分。因此，在考虑相关气候的情况下，准确了解它们的用水量和植被需求是相关的，从极端寒冷、干燥、冬季漫长的气候到热带湿热气候，因此植被变化很大。半天然草地主要用于放牧，主要指高原牧场和草甸、草原、稀树草原、潘帕斯草原和混交林系统。粮农组织通过作物系数 ( _{K c}) 参考蒸散量 (ET _o ) 采用。选定的论文是那些实际 ET _c (ET _{c act} ) 来自实地观察而 ET _o是根据 FAO56 定义或可以参考前者的另一种方法计算的论文。野外导出的 ET _{c act}方法包括土壤水分平衡、鲍文比和涡度协方差测量，以及遥感植被指数或地表能量平衡模型，因此审查了从野外数据获得的K _{c act} (ET _{c act} /ET _o )值. 这些 K _{c act}指的是初始、中期和末季 (K _{c act ini} , K_{c act mid} , K _{c act end} ) 当报告值为每日或每月时；否则，仅收集平均值 (K _{c act avg )。}对于与寒冷或冰冻冬季相关的情况，数据仅指暖季。对于为干草而砍伐的草，K _{c act ini}、K _{c act mid}和 K _{c act end}指的是一个砍伐周期。K _{c act}值很少超过 1.25，因此表明报告的现场测量确实考虑了可用的蒸发能量。总体而言，寒冷气候下半天然草地的 K _{c act  mid}低于炎热气候下的草地，除非可用水量高，K _{c act mid}为草地和山地牧场，一般高。大草原的 K _{c act mid}值低于稀树草原。通常为干草和景观种植的草通常显示出高 Kc _{act 中间}值，而观察到用于放牧的草有更大的变异性。收集到的 Kc _act值用于定义所有草地和草地的标准 Kc 值_。然而，表格中的 Kc _act是用于实际水资源管理目的和/或种植草地灌溉计划的_Kc指示值。期望更好地了解标准和/或指示性 K _c各种草地和草的价值将支持更好的管理，旨在提高草的生产力和生态系统服务，包括生物多样性和碳封存。