Winter cover crops, used as green manure, can supply up to 45 units of nitrogen per hectare to the following summer crops. In order to contribute to the establishment of the nitrogen balance sheet for fertilisation recommendation of subsequent main crop at field scale, this supply is currently derived from the biomass production, classically estimated visually using 3 classes: 0–1, 1–3, 3+ tons of dry matter per hectare (Mg DM ha⁻¹). The capabilities of Sentinel-2 satellite data to retrieve an operator-independent winter cover crop biomass have been assessed. Biomass samples were collected in 1 m quadrats for various types of winter cover fields classically used in Belgium (mustard, phacelia, oat and a range of mixed cover), in 2016 and 2017 (yield between 0.1 to 5 tons of dry matter per hectare). Empirical relationships between the winter cover crop biomass and a wide range of vegetation indices (VIs) derived from Sentinel-2 have been defined, and the most performant VI identified. For pure stands of winter cover crops, the cross-validation RMSE (CVRMSE) of the best model is 0.36 Mg DM ha⁻¹ for mustard and 0.3 Mg DM ha⁻¹ for phacelia. The CVRMSE observed for mixed stands, around 0.61 Mg DM ha⁻¹, is roughly two times higher than the CVRMSE observed for pure stands. The added-value of objective satellite-based estimation of winter cover biomass was also assessed by comparing respective estimations with regards to an independent reference dataset made of sample measurements on the ground. Models based on Earth observation showed better results than farmer visual assessment for mustard crops, and were as good as farmers for phacelia crops.

用作绿肥的冬季覆盖作物每公顷最多可为随后的夏季作物提供45单位的氮。为了有助于建立氮平衡表，以便在田间尺度上推荐后续主要农作物的施肥，目前该供应量来自生物量生产，传统上用3类目测估算：0-1、1-3、3 +每公顷干物质吨（Mg DM ha ^-1）。已经评估了Sentinel-2卫星数据检索与操作者无关的冬季覆盖作物生物量的能力。在2016年和2017年，在比利时传统上使用的各种冬季覆盖田（芥子气，phacelia，燕麦和一系列混合覆盖）的生物质样品采集面积为1 m的方方动物（每公顷干物质产量在0.1至5吨之间） 。已经定义了冬季覆盖作物生物量与源自Sentinel-2的多种植被指数（VI）之间的经验关系，并确定了性能最高的VI。对于纯种的冬季覆盖作物，最佳模型的交叉验证RMSE（CVRMSE）对于芥末为0.36 Mg DM ha ^-1，对于速殖酵母为0.3 Mg DM ha ^-1。混合林的CVRMSE约为0.61 Mg DM ha ^-1，大约是纯林分CVRMSE的两倍。还通过将各自的估计值与由地面样本测量得出的独立参考数据集进行比较，来评估基于卫星的冬季覆盖生物量客观估计值的增加值。基于地球观测的模型显示出的效果比农民对芥末作物的目测评估要好，并且与磷虾作物的农民一样好。