over-fertilize       
verb [ I or T ] (also overfertilize); (UK usually over-fertilise) uk/ˌəʊ.vəˈfɜː.tɪ.laɪz/ us/ˌoʊ.vɝˈfɝː.t̬əl.aɪz/
 过度施肥
to use too much fertilizer (= a substance spread on land or plants to make the plants grow well)
  Be careful not to overwater or overfertilize.  注意不要浇水过多或施肥过量。 
 We need to address the issue of people who over-fertilise their lawns, which can impact negatively on water safety. 我们需要解决人们给自家草坪过度施肥的问题,这会对水安全产生负面影响。 
 - More examples
 - Farmers who over-fertilize their fields threaten the quality of the water in the country's rivers.
 - The potting soil already has fertilizer added, and it is easy to overfertilize.
 - Not all the fertilizer used is taken up by the crop, especially if farmers over-fertilise to ensure that crop yields are not limited.