自古以来农业的栽培一直沿用土栽的方法。尽管生产技术和栽培条件不断提高,但它依然不能摆脱对大自然的依附。洪涝和干旱依然是威胁农业收获的主要因素,尤其是干旱近年来愈演愈烈。2001年6月报载大江南北旱情似火,360座县级以上城市缺水,涉及人口2198万。专家预测长江流域20年内将进入干旱期。节约用水,提高每一滴水的效益,值得人人关注。 众所周知硒的无机化合物毒性很大,不能以补充营养的目的直接混于食品中食用,但是硒的活性有机化合物是易为人体吸收的天然抗癌补品,可长期进补。我国已加入WTO,农产品面临挑战。增加硒含量,无疑将提升农产品的国际竞争力。但是我 Since ancient times, cultivation of agriculture has been followed by the method of soil cultivation. Despite the continuous improvement of production techniques and cultivation conditions, it still can not get rid of the dependence on nature. Floods and droughts continue to be major threats to agricultural harvests, especially as drought has intensified in recent years. In June 2001, there was a drought in both the north and south of the major rivers, and 360 cities and towns above county level were short of water, involving a population of 21.98 million. Experts predict that the Yangtze River basin will enter a drought period within 20 years. Water conservation, improve the effectiveness of every drop of water, deserve everyone’s attention. It is well-known that selenium inorganic compounds are very toxic and can not be directly mixed with foods for nutritional purposes. However, active organic compounds of selenium are natural anticancer drugs that are easily absorbed by the body and can be tonic for long periods. China has joined the WTO, and the agricultural products are facing challenges. Increase selenium content, will undoubtedly enhance the international competitiveness of agricultural products. but I