Primary Research Of Soil Fertility And Enzymatic Indication Of Soil Fertility In Cold Black Soil

Soil fertility is one of the important indicator that can reflect the soil fertile degree directly. Soil enzyme is catalyst in soil biochemical reaction. It can play an important role in the conversion of soil fertility and indicate the change of soil fertility in a certain extent. So fertility and enzymatic activity in cold black soil were measured in 2014 on the basis of the same soil samples in 2002. The data of 2014 and 2002 were compared so as discussing indicator of soil enzyme on the soil fertility in order to providing theoretical basis for the conservation of the cold black soil fertility and reasonable production. Main results were summarized as follow:1.In 2014, soil organic matter content, humic acid content, fulvic acid content, total nitrogen content, ammonium nitrogen content, nitrate nitrogen content were at higher levels, soil total nitrogen content was in the secondary level, soil available phosphorus content was at four levels. Compared with 2002, it declined in a certain degree, the drop rate were 19.96 %, 25.93 % and 80.00 % respectively. Soil total phosphorus content was in the tertiary level. Compared with 2002, it increased by 65.85%.2.Compared with 2002, soil catalase and amylase activity in 2014 increased, and the growth rate were 115.76 % and 209.34 %; urease activity, nitrate reductase and acid phosphatase activity declined, and the drop rate were 64.72 %, 96.17 % and 65.72 % respectively.3.The correlation analysis of soil fertility and enzyme activity results showed that the soil carbon content had a good correlation with themselves and phosphorus content, but nitrogen content had no correlation with carbon and phosphorus content. The factor fertility of the cold black soil in 2014 were organic matter, humic acid, fulvic acid, total phosphorus, organic phosphorus by the principal component analysis. Compared with 2002, nitrogen was no longer the main factor of soil fertility. We should advise that invertase and cellulase could be used as an important indicator of soil carbon, nitrogen, phosphorus in the cold black soil by stepwise regression analysis.