(1)Characteristics
Alfalfa is a perennial herb, with a plant height of 100-150cm and many branches on the stem. The leaves are ternately compound, and the leaflets are ovoid or elliptic. Racemes with 20-30 small flowers, purple flowers. The pods are spiral-shaped and contain 2 to 9 seeds, which are kidney-shaped and yellow-brown. Prefer warm semi-arid climate, the average daily temperature of 15 ～ 20 ℃ optimal growth, high temperature, high humidity is unfavorable to its growth. Cold resistance is strong, its cold hardy varieties can withstand -20 ~ 30 ℃, snow cover can withstand -40 ℃. The main root is stout, the root system is developed, into the soil up to 3 ~ 6m, can fully absorb the water in the deep soil, so drought resistance is very strong. The soil requirements are not strict, sandy soil, clay can grow, but the most suitable soil layer deep, rich in calcium soil, suitable soil pH in 7 ~ 8. During the growth of the most taboo water, continuous flooding for 24 hours will be a large number of deaths, so the requirements of good drainage, the water table is lower than 1m below. Salt and alkali tolerance, adult plants can tolerate 0.3% of the salt, in the NaC1 content of 0.2% of the following growth is good.
(2) Cultivation techniques Alfalfa seeds are small, fine ground preparation is required before sowing and soil moisture is maintained, and appropriate amount of stable fertilizer or phosphorus fertilizer should be applied to infertile soil as bottom fertilizer. Seeds can be sown throughout the year, and spring sowing can be done in places with good spring moisture and less wind and sand hazards. Spring drought, late frost areas can be sown at the end of the rainy season. Winter is not too cold areas can be sown in late August to mid-September, fall sowing moisture is good, weed damage is light; can also be sown in early winter before the soil freezes, send seed overwintering, the use of early spring when the soil freezes the moisture of the seedling. Generally more strip sowing, row spacing of 30 ~ 40cm, sowing depth of 1 ~ 2cm, the amount of seed sown per mu is 1 ~ 1.5kg. Seedling growth is slow, susceptible to weed infestation, should be timely weed removal. In the early spring before the return of green or after each mowing of the plow loosening, dry season and watering after mowing to improve the effect of grass production is very significant. It can be mowed 3 to 4 times a year, and generally produces 600 to 800kg of hay per mu, with a high yield of more than 1,000kg. Usually 4 ~ 5kg of fresh grass to make 1kg of hay. The sun-made hay should be mowed when 10% of the plants are in bloom, leaving a stubble height of 5cm is appropriate.
(3) Economic value Alfalfa is known as the "king of pasture", not only high grass yield, excellent grass quality, and rich in crude protein vitamins and inorganic salts. The amino acids in protein are complete, and the content of essential amino acids is rich. Dry matter in the crude protein content of 15% ~ 25%, equivalent to half of the soybean cake, higher than corn 1 ~ 1.5 times. It has good palatability and can be green fodder, silage or sun-made hay. Young alfalfa can be fed to pigs, poultry, rabbits and herbivorous fish as supplementary feed of protein and vitamin. Alfalfa grass meal can be made into pellet feed or full-value feed for livestock, poultry, rabbits and fish. Reed fescue, awnless birdseed and alfalfa are generally mixed in grazing grassland, which can not only improve the feeding value of forage, but also prevent livestock from consuming too much alfalfa to cause swelling disease. Alfalfa and sudangrass, green mowing corn and other mixed silage, feed effect is also very good. Alfalfa is a good soil and water conservation plant with strong roots. There are rhizomes growing on the roots, which can fix nitrogen in the air and increase nitrogen in the soil in addition to meeting its own nitrogen needs, so it is also a good green manure plant. Alfalfa sprouts and early spring young alfalfa branches and buds are also available for people to eat.