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【Getting a Firm Grip on Weed Control】
TEXT:This is the VOA Special English Agriculture Report.
這里是美國之音慢速英語農業報道。
When is a plant considered a weed? Experts at Penn State University have a simple answer: When the undesirable qualities outweigh the good qualities.
什么時候植物會被當成雜草？賓夕法尼亞州立大學的專家們給出了一個簡單的答案：當其不良品質超過優良品質時。
Consider the fact that crops generally produce several hundred seeds from each plant. By comparison, each weed plant can produce tens or even hundreds of thousands of seeds. And some buried seeds can survive up to forty years -- or even longer.
考慮到每株農作物通常產生幾百顆種子。而相比之下，每株雜草能產生數萬甚至數十萬顆種子。而且，一些被埋在地里的種子可以存活40年乃至更久。
Eradicating weeds means that you have to remove all the seeds and roots so the plants will not grow back. But birds or the wind can reintroduce them to the land.
根除野草意味著必須除掉所有的種子，并且將植株連根拔起，以免其重生。但是鳥或風會將種子重新帶回土地。
A more common way to deal with weeds is to control them enough so that the land can be used for planting. Experts advise using two or more control methods to deal with weeds.
一種更常見的對付雜草的方式是嚴格控制其生長，這樣土地才能種植作物。專家建議使用兩種或兩種以上的方式來對付雜草。
Chemical weed killers or natural treatments like corn gluten can suppress weed growth. But so can dense planting. Bill Curran is a professor of weed science at Penn State. He says a dense, competitive crop that quickly shades the soil from the sun will help reduce weed growth.
化學除草劑或玉米蛋白粉一類的自然控制手段可以抑制雜草的生長。作物密集種植也行之有效。Bill Curran是賓夕法尼亞州立大學的雜草科學教授。他表示，經過密植的競爭性作物會很快遮蔽陽光，這將有助于抑制雜草生長。
Other controls include turning over the soil, pulling the weeds or covering them with mulch made of wood, garden waste or other material.
其它控制手段包括翻土、拔草或用地膜覆蓋雜草。地膜一般由木屑、園林廢棄物或其他材料制成。
But even mulch has its limits. Natural resource specialists point out that weeds can be transported in mulch. This is also true of soil, grain, hay and animals.
但是，即使地膜也有其局限性。自然資源專家指出，雜草可以通過地膜傳播，還可以通過土壤，谷物，干草和動物傳播。
Yet animals like sheep or goats eat weeds, so they can provide a biological control. Insects and other organisms can also act as biological controls.
然而，像綿羊或山羊之類的動物以雜草為食，因此它們能夠提供一種生物控制手段。昆蟲和其他生物也可以起到生物控制作用。
Preventing the spread of weeds is an important part of weed management. Farm vehicles should be kept out of areas with weeds. If that is not possible, then clean off the equipment and your shoes when leaving.
控制雜草的傳播是雜草管理的重要部分。農田機器應該遠離長滿雜草的地方。如果不可能的話，離開的時候要清潔機器和鞋子。
Some people burn weeds or bury them deep in the ground or make them into mulch.
有人將雜草燒掉，或者將其深埋，或者將他們轉化成地膜。
Professor Curran says another way to make use of weeds is to compost them. The process of making organically rich compost produces heat. This heat kills many, though not all, weed seeds. The same is true for seeds that pass through animals that graze on weeds.
Curran教授說，用雜草制作堆制肥料是對雜草加以利用的好方法。制作有機堆肥的過程會產生熱量。熱量會殺死許多雜草種子。農田生物拒絕雜草的過程道理也是一樣的。
