ground and underground water for a long time． This affects crops and, therefore, animals and humans, since chemicals get inside the crops and cannot just be washed off． These chemicals in the food supply build up in people's bodies over time． Many of these chemicals can lead to cancer or other illnesses． In addition, fruit, vegetables and other food grown with chemical fertilizers usually grow too fast to be full of much nutrition． They may look beautiful, but inside there is usually more water than vitamins and minerals．

　　With these discoveries, some farmers and many customers are beginning to turn to organic farming． Organic farming is simply farming without using any chemicals． They focus on keeping their soil rich and free of disease． A healthy soil reduces disease and helps crops grow strong and healthy． Organic farmers, therefore, often prefer using natural waste from animals as fertilizer． They feel that this makes the soil in their fields richer in minerals and so more fertile． This also keeps the air, soil, water and crops free from chemicals．

　　Organic farmers also use many other methods to keep the soil fertile． They often change the kind of crop in each field every few years, for example, growing corn or wheat and then the next year peas or soybeans． Crops such as peas or soybeans put important minerals back into the soil, making it ready for crops such as wheat or corn that need rich and fertile soil． Organic farmers also plant crops to use different levels of soil, for example, planting peanuts that use the ground's surface followed by vegetables that put down deep roots． Some organic farmers prefer planting grass between crops to prevent wind or water from carrying away the soil, and then leaving it in the ground to become a natural fertilizer for the next year's crop． These many different organic farming methods have the same goal: to grow good food and avoid damaging the environment or people's health．

　　化学耕作还是有机耕作？

　　在过去的半个世纪里，在耕作中使用化学肥料已经非常普遍。许多农民喜欢使用化肥，把化肥作为防治农作物病虫害和增产的重要手段。然而，最近科学家们发现长期使用这些肥料会对土地造成损害，甚至更危险的是，会对人们的健康造成危害。

　　化学肥料都能造成哪些问题呢？首先，它们杀死有害细菌和害虫的同时也杀死了有益细菌和益虫，从而对土地造成损害。化学肥料还会在土壤和地下水中保存很长时间。这将会影响农作物，因此影响到动物和人类，因为化学物质会进入到农作物里面，并且不能被冲洗掉。食物中的这些化学物质会随着时间的推移而在人体内逐渐堆积。很多化学物质能导致癌症或其他疾病。另外，使用化学肥料种植的水果、蔬菜和其他食物通常生长过快而缺少足够的营养。它们可能看起来很好，但里面通常含更多的水分而不是维生素和矿物质。

　　由于这些发现，一些农民和很多消费者开始转向有机耕作。有机耕作就是不使用任何化学肥料的耕作。他们主要是想保持土壤肥沃且免受病害。健康的土壤能减少病害并促进农作物茁壮生长。因此，有机耕作的农民通常更喜欢使用天然的动物粪便作肥料。他们认为这样能使土壤中的矿物质更丰富因而也会更肥沃。这也能使空气、土壤、水和农作物不受化学物质的污染。

　　有机耕作的农民也使用很多其他的方式保持土壤肥沃。他们经常每隔几年就在一块土地里更换一次农作物，例如，今年种植玉米或小麦，来年改种豌豆和大豆。像豌豆或大豆这样的农作物能使土壤重新富含重要的矿物质，这为种植需要肥沃土壤的农作物，如小麦和玉米等做好了准备。有机耕作的农民也使用不同的土壤层种植作物，例如，先种植生长在表层土壤的花生，然后种植生根于深层土壤的蔬菜。有些有机耕作的农民喜欢在农作物之间种草来防止水土流失，然后将草留在地里成为来年农作物的天然肥料。这些不同的有机耕作方式有一个相同的目标：种植好粮食并避免损害环境和人们的健康。

　　1．It is important to explain this again or we will confuse the students．(P13)

　　把这个再解释一遍很重要，否则我们就会使学生感到迷惑。

★confuse vt．使迷惑；使为难