lawn is different from agriculture land. We never take things away from it. Chemical fertilizer are being used on lawns for many years in Canada without problem. Only parts of lawn with high traffic will become compressed. "我春天用那种叉子给草地打洞" will help provent that. Usually there is enough earth worm in lawn to loose it up. Leave grass clipping on the lawn provides food for earth worm,when they go to the surface to get it they 打洞 for us.
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