Actual and standard crop coefficients for semi-natural and planted grasslands and grasses: a review aimed at supporting water management to improve production and ecosystem services

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