What is the fine-grained topic of the following text: According to the report, after using the “Harbest Soil Conditioner” developed by Western Environmental Protection Co., Ltd (Hereinafter referred to as Western Environmental Protection), in heavy-metal pollution remediation test area in Changzhutan, the cadmium-reducing rate of rice is about 30%, and the content of soil available cadmium is reduced by more than 15%, meanwhile the soil pH is increased by 0.33-0.85. Only return the topic.
The efficacy of "Harbest Soil Conditioner" by Western Environmental Protection Co. Ltd in reducing heavy-metal pollution.