But water containing the herbicide cannot be released back into the river and it is known that low water levels can harm river ecosystems accustomed to higher levels.
The attempts to increase production with the use of oil-based fertilizers, insecticides, and herbicides cannot continue as oil grows scarce, and in any case, its effects on the land are harmful.
3
文章着重阐述了杂草的危害、苗圃常用的除草剂及用量、安全用药技术。
It is expatiated that harmfulness of weed, varieties and dosage of common weedicides, and use technique of weedicides in forest nurseries.