The main conclusions drawn from the study are as follows:Lit is unable to evaluate SSC of paddy soil with 1M HAc-NaAc(pH4) method directly within wide pH range, because some unavailable silicon for plant can be extracted from soil which pH value are high.

• 由于1M HAc-NaAc(pH 4)缓冲液酸度过强，用该法测定的土壤有效硅含量不能直接判断广泛pH范围的水稻土供硅能力。