Agricultural land use and management affect land surface albedo and thus the climate. Increasing the albedo of cropland could enhance reflection of solar radiation, counteracting the radiative forcing (RF) of greenhouse gases (GHGs) and local warming. However, knowledge is lacking on how agricultural practices affect albedo under local conditions, and on the benefits of individual practices. In this study, field measurements were made in 15 paired plots at a site in Northern Europe to determine albedo, net shortwave irradiance and RF impacts under various common crops, cultivation intensities and tillage practices. Field data for 2019-2020 were compared with satellite-based albedo for the surrounding region in 2010-2020. At regional level, different combinations of soil type, yearly weather and agricultural practices led to great variability in the albedo of individual crops, despite similar pedo-climatic conditions. At field level within years, albedo differences were determined mainly by crop type, species-specific phenology and post-harvest management. Annual albedo was higher with perennial ley (0.20-0.22) and winter-sown crops (0.18-0.22) than with spring-sown crops (0.16-0.18) and bare soil (0.13). Barley had the highest albedo among winter and spring cereals. In summer, when increased albedo could alleviate local heat stress, oats reduced net shortwave irradiance at the surface by 0.8-5.8 Wm⁻² compared with other cereals, ley, peas or rapeseed. Delayed or reduced tillage gave high local cooling potential (up to -13.6 Wm⁻²) in late summer. Potential benefits for global mean climate as GWP₁₀₀ per hectare and year reached -980 kg CO₂e for avoiding black fallow, -578 kg CO₂e for growing a winter-sown variety and -288 kg CO₂e for delayed tillage. Thus realistic albedo increases on cropland could have important effects on local temperatures and offset a substantial proportion of the RF deriving from field-scale GHG emissions on short time-scales.

农业用地和管理影响地表反照率，从而影响气候。增加农田的反照率可以增强太阳辐射的反射，抵消温室气体 (GHG) 的辐射强迫 (RF) 和局部变暖。然而，缺乏关于农业实践如何在当地条件下影响反照率以及个人实践的好处的知识。在这项研究中，在北欧一个地点的 15 个配对地块中进行了现场测量，以确定各种常见作物、耕作强度和耕作方式下的反照率、净短波辐照度和射频影响。将 2019-2020 年的现场数据与 2010-2020 年周边地区的卫星反照率进行了比较。在区域层面，土壤类型的不同组合，尽管土壤气候条件相似，但每年的天气和农业实践导致个别作物的反照率有很大差异。在几年内的田间水平上，反照率差异主要取决于作物类型、特定物种的物候和收获后管理。多年生麦草 (0.20-0.22) 和冬播作物 (0.18-0.22) 的年反照率高于春播作物 (0.16-0.18) 和裸土 (0.13)。在冬季和春季谷物中，大麦的反照率最高。夏季，当增加反照率可以缓解局部热应激时，燕麦减少地表净短波辐照度0.8-5.8 Wm 多年生麦草 (0.20-0.22) 和冬播作物 (0.18-0.22) 的年反照率高于春播作物 (0.16-0.18) 和裸土 (0.13)。在冬季和春季谷物中，大麦的反照率最高。夏季，当增加反照率可以缓解局部热应激时，燕麦减少地表净短波辐照度0.8-5.8 Wm 多年生麦草 (0.20-0.22) 和冬播作物 (0.18-0.22) 的年反照率高于春播作物 (0.16-0.18) 和裸土 (0.13)。在冬季和春季谷物中，大麦的反照率最高。夏季，当增加反照率可以缓解局部热应激时，燕麦减少地表净短波辐照度0.8-5.8 Wm⁻²与其他谷物、麦芽、豌豆或油菜籽相比。延迟或减少耕作在夏末产生了较高的局部冷却潜力（高达-13.6 Wm ^{-2 ）。}全球平均气候的潜在收益为每公顷每年GWP _{100达到 -980 kg CO 2} e（避免黑色休耕），-578 kg CO ₂ e（种植冬季播种品种）和 -288 kg CO ₂ e（延迟耕作）。因此，农田的实际反照率增加可能对当地温度产生重要影响，并抵消在短时间内由田间尺度温室气体排放产生的很大一部分 RF。