Fertilization of legumes

The family of legumes mainly includes clover, alfalfa, serradella, beans, peas, lentils, soy and liquorice. These are plants the growing of which significantly positively affects the fertility of our soils by enriching it with nitrogen and contributing to their loosening. Growing legumes (otherwise fabaceae), however, requires proper care and provision of the right amount of nutrients.



How important legumes are in rotation crops know all farmers: grown for green manure they improve the lumpy soil structure its water and thermal conditions, they enrich it with nitrogen (50 to 250 kg / ha) and significant amounts of phosphorus, calcium, sulphur, potassium and magnesium. Grown for fodder (in the form of green fodder, hay, silage or seeds) legumes provide animals with large amounts of protein, vitamins and minerals. Fertilization of legumes should take into account all the minerals necessary for plants. In specific soil conditions, therefore, it is necessary to use multi-mineral fertilizers such as:

– SuproFoska 11

– SuproFoska 14

– SuproFoska 20

– SuproFoska 22




Due to the specific properties of legumes i.e. the symbiosis with root-nodule bacteria that bind atmospheric nitrogen from the soil air, these plants are generally not fertilized with nitrogen. In the presence of nitrate and ammonium salts appearance of nodules on the roots is difficult or stops completely. Also, too acidic soil may be another reason why warts are not formed. In both cases, nitrogen fertilization is not able to replace the specific nature of symbiosis – yield and nitrogen content in the biomass decrease. Visible symptoms of nitrogen starvation are: yellowing and pan-purple leaves, slender shape of plants as well as poor flowering and fruiting. On soils very poor in nitrogen it is advisable to apply the fertilizer: SuproFoska 11 or SUPROFOS 25, while on soils with sufficient nitrogen content other fertilizers of the SuproFoska series may be used.

Phosphorus (P)

Optimal supply of phosphorus for legumes promotes binding of nitrogen by root-nodule bacteria and facilitates converting of mineral nitrogen into protein. Failure to fertilize with easily assimilable phosphorus will always, regardless of the fertility of soil, cause rapid and significant reduction of yields. External symptoms of lack of phosphorus is a slowdown of growth, soaring shape of plants, purple and brown colouration of the oldest leaves as well as delayed maturation. On soils particularly poor in phosphorus legumes should be fertilized with a fertilizer with a high concentration of phosphorus, e.g. simple granular Superfosfat. On other soils fertilizers like SuproFoska 14, SuproFoska 22 or SuproFoska 20 can be used.

Potassium (K)

For a good yield of legumes, especially clover and alfalfa, it is necessary to apply potassium fertilization. Symptoms of potassium deficiency are: laxity of plants, their small size, drying out leaves. Characteristic are very fine and numerous necrotic spots between leaflet veins. In most cases, a sufficient amount of potassium for legumes is introduced by fertilizers: SuproFoska 14, SuproFoska 20, SuproFoska 22 or SUPROFOS 25.

Calcium (Ca)

Legumes require large amounts of calcium in the soil (soil should not be limed only for yellow lupine and serradella). Symptoms of lack of calcium in plants these are: folding and then breaking of stem tops and dying of inflorescences. All fertilizers produced by FOSFAN contain sufficient amounts of calcium for legumes. Liming is necessary only on very acid soils.


The presence of magnesium in the soil facilitates uptake of phosphorus by plants. Legumes collect much larger amounts of magnesium than other crops. All legumes react to deficiency of magnesium in the soil. Characteristic symptoms of deficiency include yellow-green colour of leaves with darker streaks of green along the innervation (so called marbling). On soils particularly poor in magnesium, it is advisable to use fertilizers: SuproFoska 20 and SUPROFOS 25 or even use calcium-magnesium fertilizers.

Sulphur (S)

Legumes require extremely large amounts of sulphur in the soil. On soils poor in sulphur introduction of this element significantly improves the yield of these crops. Most soils are now showing a lack of sulphur that is the reason why it is advisable to use fertilizers such as SuproFoska 11 or SuproFoska 14 in which the amount of assimilable sulphur amounts to more than 20%. Common symptoms of lack of sulphur are often confused with symptoms of a lack of nitrogen, because in both cases plants are small and chlorotic.





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