Alfalfa

Alfalfa (Medicago sativa)

Leguminosae ( Leguminosae) alfalfa genus of perennial herbs. Also known as alfalfa, clover. An important forage and green manure crops.

Origin and distribution Alfalfa is native to Asia Minor, Iran, Transcaucasia. It was cultivated in Persia in 700 BC. It was introduced into Greece from Midian (the ancient kingdom in northwestern Iran) around 500 BC, into Italy from the 2nd to the 1st century BC, into Spain in the 8th century, into the Americas in the 16th century, and began to be planted in Australia and New Zealand in the 18th century. China in 126 BC by Zhang Qian mission to the Western Regions from the ancient Sydney (i.e., today's Kashmir) introduced, first in the emperor's palace near the planting, only for the imperial horse feed. Later it was popularized from Xi'an to the Yellow River basin. Now alfalfa is widely planted all over the world, and in the 1970s, the total cultivated area of the world was more than 33 million hectares, of which the United States accounted for about 32.7%, and since the 1980s, the cultivated area of China has reached more than 1 million hectares, mainly distributed in the northern provinces.

Morphology and Characteristics The main root of alfalfa is well developed, with many lateral roots, and the main root enters into the soil more than 2 meters, and can reach about 10 meters in the drier areas. The stem is 30-100 centimeters high, erect or decumbent, rounded or angular, with sparse hairs on young stems, rhizomes are well developed, and the branches born from the expanded root necks are generally 15-60, with a maximum of 100 or more. Leaves are trifoliolate, obovate, broader at the apex, and toothed. Flowers in racemes, axillary 8-25 purple butterfly-shaped flowers. The pods are spiral-shaped, 2 to 4 rings, dark brown, with 4 to 8 seeds per pod. Seeds are kidney-shaped, yellow-brown, with a weight of 1.5-1.9 g per thousand seeds (see picture).

Alfalfa has wide adaptability, but prefers warm, sunny and dry climate with little rain. Annual precipitation of 500 to 900 millimeters is the most suitable, more than 1000 millimeters is not conducive to growth; less than 300 millimeters and no irrigation conditions are difficult to grow normally. Cold hardiness, seeds can germinate at 4 to 6 ℃. Seedlings can withstand a short period of -5 ~ -6 ℃ low temperature, adult plants can withstand -20 ~ 30 ℃ low temperature. In the snow cover, -40 ℃ low temperature will not cause frost damage. The optimal temperature for growth is 20～25℃, high temperature will inhibit growth. Need more water; each formation of 1 gram of dry matter consumes about 446 to 500 grams of water, each formation of 1 gram of seed consumes about 800 grams of water. But because of the developed root system, there is a strong drought resistance. Most avoid waterlogging, flooding during the growing season 24 to 28 hours that a large number of deaths. To deep soil, water table below 2 meters, well-drained neutral soil planting is appropriate.

China has screened out a number of good varieties, such as Guanzhong alfalfa, which is early and fast-growing; Longdong alfalfa, which is high-yielding and large in size; Xinjiang big-leaf alfalfa, which has strong regeneration ability; Jinnan alfalfa, which is medium-mature; and Northeastern alfalfa, which is strong in hardiness and cold resistance, etc, which are all well adapted to local ecological environments.

Cultivation Before sowing, the ground should be prepared to preserve moisture. Northern China generally take winter sowing "send son" (seed sown into the soil, to be early after the next spring seedlings) or early spring top sowing, in order to facilitate drought protection seedlings. Northeast China, Northwest China and Inner Mongolia and other places in the fall sowing can not be later than the first half of August; North China should be in September before. Late sowing is poor root development, affecting overwintering. Pure seeds with high germination rate, about 15 kg per hectare, and other crops can be appropriately reduced when mixed sowing. Strip sowing row spacing is generally 15-30 cm, sowing depth 1.5-2 cm. Seedling growth is slow, to strengthen management, to prevent weed infestation. After mowing, we should timely apply fertilizer, especially phosphorus and potassium fertilizer. Common pests include aphids, thrips, alfalfa blind stinkbugs, alfalfa nightshade moths, leaf miner flies; diseases include botrytis, downy mildew, rust, brown spot, powdery mildew and so on. After the use of pesticides, it is necessary to feed livestock after a certain interval in order to prevent poisoning. Cultivation of seed retention should choose higher terrain, well-drained plots, the amount of seed sown per hectare is 7.5 to 11 kg, row spacing 40 to 60 cm, increase the application of phosphorus and potassium fertilizer. Bee or artificial pollination can improve seed production.

Utilization of alfalfa is rich in nutrients, palatable, easy to digest, known as the "king of pasture". The grass contains 76% of moisture from the first flower to the full bloom period, 4.5-5.9% of crude protein, 0.8% of crude fat, 6.8-7.8% of crude fiber, 9.3-9.6% of nitrogen-free leachate, 2.2-2.3% of ash, and contains a variety of amino acids. Alfalfa land can be directly grazed, but the green stems and leaves contain saponin, to prevent livestock from overfeeding bloat disease. It can also be made into silage or hay. From the bud to the early flowering period, about 10% of the stems and branches to open the first flower when mowing the first crop of fresh grass, the quality is more tender, higher nutritional value. Early mowing is low yield, late cutting is increased stem lignification, and easy to lose leaves. The last crop should be mowed about 1 month before the local frost. Each time to leave 3 to 5 cm of stubble, so as not to mow the root neck, the last mowing each year, to leave 8 to 10 cm of stubble. Northern arid areas of pre-winter cut soil, favorable regeneration the following year.

Alfalfa root volume, deep into the soil, nitrogen fixing ability, 2 to 4 years old plants per hectare per year can fix nitrogen 150 to 450 kg. Root decay can increase soil organic matter, improve physical properties, and improve soil fertility. The implementation of crop rotation between grain crops and alfalfa in low-yield areas in northern China is conducive to improving grain yield. Fresh grass contains 0.54-0.57% nitrogen, 0.10-0.14% phosphorus and 0.31-0.46% potassium oxide. Turning for green manure, fertilizer effect is remarkable. Purple clover cover luxuriant branches and leaves, covering the ground can reduce evaporation, water retention, reduce the surface scouring, is an important crop of soil and water conservation. Such as alfalfa plots in northwest China, rainwater loss is only 1/16 when planting other crops, soil scouring is only 1/9. 346 millimeters of annual precipitation in the region, per hectare of alfalfa land each year, the soil washed away 93 kg, while other fields or recreational land scouring can be as high as 3,600 to 6,750 kilograms.

One species of alfalfa in the genus Alfalfa, family Leguminosae. Perennial, much branched. Leaves compound with 3 ovate or oblanceolate leaflets. Flowers densely arranged in axillary racemes; calyx hairy, calyx teeth narrowly lanceolate; corolla purple, butterfly-shaped, longer than calyx; stamens 10, dimorphic (9+1); ovary hairy. Pods spirally coiled, containing several kidney-shaped seeds. Other alfalfa species that can be used as forage or green manure are: southern alfalfa, sky blue alfalfa, wild alfalfa, small alfalfa, and brown-spotted alfalfa.

There are about 60 species of alfalfa in the genus Alfalfa, distributed in Europe, Africa and Asia. There are many artificial cultivars. China produces 12 species. Alfalfa is native to Central Asia, is a kind of excellent pasture grass, has the advantages of wide adaptability, high yield, good quality, resistant to mowing, and can increase soil fertility, etc., so it has the name of "king of pasture grass", Chinese cultivation of alfalfa started from 126 B.C. when Emperor Wu of Han Dynasty. So far, it is still planted more in northwest provinces.