VOA慢速英语2012.06.01 的, harder, 英语, animal, farmers

Rebecca949

Also, organic farmers can improve their yields by making sure their crops get enough fertilizer. But increasing the nitrogen is harder to do organically, using just animal waste and crop rotations. Organic farmers rotate food crops with plants that fertilize the soil.此外，有机农民可以给作物施足量的肥料以提高产量，但仅仅使用动物粪便和作物轮作这种方式增加氮量很难。有机农民将粮食作物与能肥田的作物轮作。
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马凯230

我想看答案

gqinchunh123

study

pxlcqy

看看。

幻化成雪

but whie this crop .....food crop...and farmers .that require

jiaoyangrenshen

http://bbs.tingroom.com/thread-409671-1-1.html