广播电视英语短句 第 340 课：改良土壤-5

And, finally, do not add diseased vegetable plants to the pile if the compost will be used on a vegetable garden. 最后，如果你想把混合肥用于蔬菜园，就不要堆积生病的植物。

Disease organisms may reappear if you do. 否则须提防这些病源体再次出现。

Compost differs from mulch but it can be used as mulch. Mulch is placed on top of soil to protect it. 混合肥虽有别于护根，但用途相似。护根是放在土壤表面起保护作用。

Mulch is generally used to a height of about ten centimeters. 它一般用于大约十厘米高的作物。

But finer materials such as compost should only be two and a half to seven and a half centimeters high. 而像混合肥这类的优质原料也仅用于二点五厘米到七点五厘米高的作物。

Too much mulch can restrict oxygen and water flow. 过多的护根则有碍于氧气和水流通。