Protein crops are annual plants belonging to the legume family (or Fabaceae) which has nearly 18,000 wild and cultivated species, specifically in the Papilionaceae sub-family.
Like all plants of this group, protein crops have the unique property among crops of not requiring any nitrogen fertilizer supply: indeed, these plants can use atmospheric nitrogen (in addition to soil mineral nitrogen, like other crops) for their nutrition via a symbiosis with nitrogen-fixing bacteria in nodules located on their roots. This feature largely explains their beneficial effect on the environment: the manufacture and application of nitrogen fertilizers (manufactured with the use of fossil fuels) and the gamut of different forms of nitrogen which result, form by far the largest single energy consumption, emission of greenhouse gases, acidifying gases and fine particles induced by conventional crop production systems. Moreover, the introduction of protein crops in rotations lacking diversity can significantly improve the agronomic performance of subsequent cereal crops and reduce both their nitrogen fertilizer and weed control requirements.
The other characteristic of legumes is related to their seed composition, rich in protein with an amino acid profile complementary to that of cereals for human and monogastric animal diets. Many species of legumes are cultivated worldwide for animal and human food. Depending on the composition and uses of the seed, there are three categories of pulses:
- The "pulses" whose seeds are rich in starch (40-50%) and protein (20-30%), which include a large number of species: peas, faba beans, peas chickpea, lentil, grass pea, beans, pigeon peas, cornille, mung bean...
- Oilseeds whose seeds are rich in oil (20-40%) and protein (20-40%) and which are usually crushed to separate the oil and meal soybean, peanut ...
- Finally, lupins, which are a separate group, of seeds without starch, high protein (30-40%) and a little oil (8-10%) and not crushed to extract the oil.
World agriculture is facing major challenges: to increase food supplies for a growing world population while reducing the use of fertilizers and pesticides. Currently, pulses, soya included, represent only 3% of European arable land: this means that the EU agriculture depends heavily on the import of vegetable protein, soy in particular, and is vulnerable to volatile soybean prices and the use of nitrogen fertilizers.