Species: Trifolium pratense L.
French: Trèfle; English: Red clover; Spanish: Trebol violet; German: Rotklee.
Origin and diffusion
Pratense or violet clover has undoubtedly been one of the most widespread forage legumes in Europe for some time and in some countries of the old continent it reaches extensions of several hundred thousand hectares.
In Italy, however, the pure cultivation of this grass legume has been gradually losing interest over the past twenty years.
Of not very ancient cultivation, the Pratense clover probably arrived in Europe through Spain and, from here, it spread to France, Germany and the Netherlands.
Already known as a fodder plant, the Pratense clover was never extensively cultivated and became a plant of primary importance only when, introduced in England in the mid-1600s, it was included in the rotation to replace the fallow fallow. The consequences of this arrangement were twofold: on the one hand it caused a significant increase in fodder availability and, on the other, thanks to its nitrogen-fixing capacity and the consequent enrichment of the nitrogen content of the soil, it allowed an increase in all agricultural production.
Pratense or violet clover - Trifolium pratense L. (photo website)
Pratense or violet clover - Trifolium pratense L.
The root system of the Pratense clover consists of a small branched taproot, which is why it is rather superficial. The stems are erect, branched, hollow, up to 0.8 m high. the leaves are trifoliate, with full-margin oval leaflets, bearing a light green V-band on their upper face. The inflorescences are globular, flower-shaped, composed of numerous (80-100) small, tubular flowers, of a more or less intense pink color, tending to purplish. Fertilization, exclusively crossed, is ensured by pollinating insects (bees, bumblebees).
The fruit is a small uniseminated legume, the seeds are small (1000 weigh 1.6-1.8 g), almost pear-shaped (globular on one side, thinner on the opposite side), bright yellow in color with nuances of violet very variable from seed to seed and from one part to the other of the same seed.
The Trefoil Prato is a physiologically multi-year species, in practice, however, it behaves as a biennial species, since at the end of the 2nd year almost all the plants died either from drought or from attacks of fungi. Therefore, the Trefoil in the southern European countries lasts only two years in cultivation, only in Northern Europe the local varieties last 4-5 years.
Environmental needs and cultivation technique
Prato's clover has a more northern distribution area than that of alfalfa, as it better resists the cold, but does not adapt to hot and dry climates due to its rather superficial root system.
As for the soil, it prefers that of medium texture, fresh, well tolerates moist, very heavy, slightly calcareous, acidic (pH 5-7.5, optimum 6-7), unsuitable for alfalfa.
Pratense clover is an excellent improvement crop which, therefore, is suitable for following and preceding wheat or another related cereal. It is impossible to grow Pratense clover on land that hosted it a short time before, therefore it is absolutely essential that the Pratense clover enters long rotations, in which it spends a long period (at least 5 years) between two successive crops of this legume.
Given the short production cycle and the slow development in the 1st year, there is no convenience in sowing the Pratense clover in specialized cultivation, in Italy the normal technique was sowing in bulatura in the middle of a cereal, but with the Intensive cultivation of wheat are scarce the chances of survival of the leguminous plants sown in it.
The most usual time for sowing is February-March, for sowing 30-35 kg / ha of seed are used.
Variety and use
In the Pratense clover, cross fertilization is the absolute rule as plants are totally self-incompatible.
In each region there were local populations ("ecotypes") well adapted to particular environmental conditions. Today only selected varieties can be traded. Renowned Italian ecotypes were Bolognino or Pescarese, Spadone.
Production in the 1st year is very low, there are only inherent stubble which, at most, can be exploited with prudent grazing. The full, mowable production is obtained only in the 2nd and last year in which the lawn gives two excellent cuts, one in mid-May, the other in late June, only in very favorable environments and vintages, sometimes a very modest third cut can occur .
Hay yields are 5-6 t / ha. An excellent hay of violet clover cut at the beginning of flowering has a s.s content of about 86%, raw protids of 17-18% (on s.s.) and a nutritional value of 0.6-0.65 U.F. per Kg of s.s.
The Prato clover seed is produced on the 2nd cut: the productions are low (100-200 Kg / ha) and are made very uncertain by several difficulties: scarcity of pollinating insects, attacks of insects (Apion pisi), lodging, ginning.