Green manures: what is it, requiremnts and advantages


We have talked a lot about the benefits and wonders of compost in the last few posts but we lack a small detail to comment on, which in addition to complementing the compost and reducing its consumption a little in our crops, it is a faster and not worse way of add nutrients to the soil. They are green manures .



Green manures consist of plants with a fast and leafy vegetative development , which will provide numerous nutrients to the soil, mainly due to the fact that we will mow them at the time of flowering, just before fruiting, which is when they will begin to absorb the nutrients. from the soil to form seeds, which are the great nutrient stores of plants to ensure survival.


For a plant to be considered green manure, it must meet a series of requirements:

  • Grow satisfactorily in poor soils.
  • Produce large volume of green dough.
  • Consume the minimum amount of water possible.
  • Have a rapid growth cycle.
  • Possess an extensive and penetrating root system with which to explore as far as possible, especially in depth.
  • Even having the ability to develop alongside the main crop without competing with it.

As a general classification we can consider green manures  forage plants, grasses and even spontaneous flora. There are numerous combinations of species studied to take advantage of them as green manures.

If what we are cultivating is a small garden (small farm, family garden …) the best possible combination will be vetch with forage beans. Why? Very easy. The forage beans will sometimes reach up to 2m in height.

The vetch tends to be more creeping so it will become entangled in its companion, making the plot a small and lush “jungle”. This, together with the spontaneous flora that can creep into the crops, will generate a large green mass that we will incorporate into the soil at the time of flowering, as we have mentioned before.

In addition, the combination of forage beans and vetch is one of the most balanced and one that best nourishes the soil.

Being the two legumes, they provide nitrogen in their vegetative phase and as if that were not enough, the stems of the broad beans have a high cellulosic and carbon content that in the end will become stable humus.


We can list the advantages of the incorporation of green manures in:

  • Improvement of the structure of the surface horizons of the soil.
  • Softness and use of subsoil water and nutrients by using deep-rooted species.
  • Defense against erosion.
  • If legumes are planted, we achieve the contribution of nitrogen to the soil and its fixation, preventing it from leaching.
  • They control adventitious vegetation.
Here we list some of the species most used in green manures:


  • Link ( Vicia sativa )
  • Horse bean ( Vicia faba minor )
  • Alfalfa (Medicago sativa)
  • Altramuz ( Lupinus albus )
  • Trébol encarnado ( clover )
  • Sweet clover ( Melilotus alba )
  • Forage pea ( Pisum sativum )



  • Oats ( Avena sativa )
  • Cebada ( Glycine max )
  • Sorghum ( Sorghum spp. )
  • Rye ( Cereal rye )


  • White mustard ( Synapsis alba )
  • Nabo (Brassica napus)


If you know more species, do not hesitate to comment! Mariano Bueno dedicates a section to green manures to complement surface composting in his book How to make a good compost . Until next time!

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