Many farmers grow their own food separately from the chemically-raised crops they sell.
2
导致这一演替的主要原因为作物布局、耕作制度、栽培方法、管理技术的变化和农药化肥的过量施用。
The main reason for this succession might be the changes in crops distribution, cultivation type, planting method, management technique and over-use of chemical pesticides and fertilizers.
Natural soil fertility is dropping in many areas because of continuous industrial fertiliser and pesticide use, while the growth of algae is increasing in lakes because of the fertiliser run-off.