For several decades, chemical fertilizers have been used to improve the productivity of agricultural soils. Produced by industries, these synthetic fertilizers are responsible for massive pollution of soil and water. When they are spread too widely and are no longer taken up by plants, nitrates from nitrogen fertilizers seep into the soil and reach groundwater. Before the 1950s, the nitrate content per liter of water did not exceed 1 mg. Nowadays, it easily exceeds 50 mg/l, the limit beyond which the WHO considers water unsafe to drink. Nitrates contribute to the proliferation of green algae in rivers and seashores. Authorized in agricultural areas, synthetic fertilizers have been banned since 2019 for sale to individuals. Among the most interesting alternatives for gardeners are green manures, those plants used for the purpose of fertilizing the soil. It’s the right time to sow it!