"How much fertilizer do you need to give you good yields and then how much is maybe a marginal gain from adding lots more fertilizer? There is really a question here: can you maybe [reduce the amount] and get close to the same level of yield without having such a negative impact?" said Packman. Packman.说:"需要多少肥料才能保证高产?增加更多肥料的边际收益又是多少?问题就在于:是否能够在不产生如此多的负面影响的情况下尽可能获得同等的收益? ______________________ Storms in the next few month will mix the gulf water and the dead zone will disappear, but it will return next year. And scientists say it will grow larger in years to come, if something is not done to reduce the amount of nitrogen in the Mississippi River. 未来几月的暴风雨将会翻动墨西哥湾的水,死水区也会消失,但在明年又会重现.科学家表示,如果不采取措施来减少密西西比河水里的含氮量,那么死水区的面积会越来越大. And that's the VOA Learning English Agriculture Report. I'm Caty Weaver. 以上就是本期美国之音慢速英语农业报道的全部内容.我是Caty Weaver.
