Rare earths contain heavy metals, which can easily cause heavy metal poisoning.
Light rare earths include: lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium.
Heavy rare earths include: gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium.
Rare earths are known as industrial "gold", due to their excellent physical properties such as photoelectricity and magnetism, can be composed of other materials with different properties, a wide range of new materials, its most significant function is to significantly improve the quality and performance of other products.
Dramatically improve the tactical performance of steel, aluminum alloys, magnesium alloys, titanium alloys used in the manufacture of tanks, aircraft, missiles. Moreover, rare earths are likewise lubricants for electronics, lasers, the nuclear industry, superconductivity and many other high technologies.
Extended Information
Research results show that rare earth elements can increase the chlorophyll content of plants, enhance photosynthesis, promote root development, and increase nutrient uptake by the root system. Rare earths can also promote seed germination, increase seed germination rate and promote seedling growth. In addition to the above main role, it also has the ability to make certain crops enhance resistance to disease, cold and drought.
A large number of studies have also shown that the use of appropriate concentrations of rare earth elements can promote plant nutrient absorption, transformation and utilization. Corn with rare earth seed mixing, seedling emergence, nodulation 1 to 2 days earlier than the control, plant height increased by 0.2 meters, early maturity of 3 to 5 days, and full grain, yield increase of 14%.
Soybean seed mixing with rare earth, emergence 1 day earlier, the number of pods per plant increased by 14.8 to 26.6, 3 pods increased, yield increase of 14.5% to 20.0%. Spraying rare earth can make the Vc content, total sugar content, sugar-acid ratio of apple and citrus fruits increase, and promote fruit coloring and early ripening. And it can inhibit the intensity of respiration during storage and reduce the decay rate.
Reference? Baidu encyclopedia-rare earth