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Abstract The rice soil (last crop was rice) and arid red soil (last crop was corn) were used as a test material for the pot experiment. The variation of enzyme activity in flue-cured tobacco-growing soil planted with different last-season crops was investigated at different growth stages in this study. The results showed the activity variation of the 3 enzymes differed in the 2 soils at different growth stages. The catalase activity in the arid red soil trended to decrease overall from the vigorous growing stage to harvesting stage; while it decreased gradually in the rice soil until the harvesting stage. The phosphatase activity in the 2 soils all increased with the proceeding of growth period. The urease activity in the arid red soil decreased gradually at different growth stages, but the variation of urease activity in rice soil was irregular. During the growth of flue-cured tobacco, the catalase and urease activity in the arid red soil increased first and then decreased, and the phosphatase activity increased gradually. In rice soil, the catalase activity increased first and then decreased; the phosphatase activity decreased first and then increased; the urease activity increased first, then decreased and increased last. The activity of all the enzymes in the 2 soils showed significant differences compared to the control except some enzymes at the vigorous growing stage. It was suggested the planting of fluecured tobacco would affect greatly the soil enzyme activities.
Key words Flue-cured tobacco; Soil type; Soil enzyme activity; Growth of flue-cured tobacco
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Soil enzymes play an important role in nutrient cycling and energy conversion in the soil ecosystem. The enzyme activity is an important indicator that reflects the soil nutrient transformation capacity11^, and it is also one of the signs that reflect the strength of soil biological activity131. Among the soil enzymes, the urease, catalase and phosphatase are the common soil enzymes. The catalase activity could characterize the soil biological oxidation process and the strength of soil redox capacity to some extent141. The catalase activity is closely related to the number of aerobic microorganisms in soil. Phosphatase is a hydrolytic enzyme. The enzymatic action will accelerate the dephosphorization rate of organic phosphorus, improving the effectiveness of soil phosphorus. The transformation...