Effect of long-term fertilization on soil enzyme activities in black loessial

The soil enzyme activities were studied after N and/or P applied for 16 years continuously. The results showed that catalase activity reduced with the increase of P rates, urease activity increased with N rates, effect of urease and alkaline Phosphatase activities on organic C, total N were positive significantly, but catalase alkaline Phosphatase affected the soil Olsen-P content negatively, invertase, urease and alkaline Phosphatase activities affected yield significantly through path analysis. The soil enzyme activities were the results of soil physical and chemical properties together effect; enzymatic factors can express the influence of fertilization on soil fertility.