Abstract:

Through exploring the effect of continuous cropping on the eco-stoichiometric characteristics of carbon, nitrogen and phosphorus and enzyme activities in Lanzhou lily soil, the study aims to provide a theoretical basis for analyzing the mechanism of partial cropping obstacles in Lilium davidii var. and the regulation of farmland nutrients. By measuring and analysis of soil eco-stoichiometric characteristics and enzyme activities of Lilium davidii var. of different cultivation years (1, 2 and 3 years), the results showed that: (1) with the increase of planting years, the soil pH decreased, while the contents of soil organic matter, total nitrogen, total phosphorus, alkali-decomposed nitrogen and available phosphorus generally increased, and the increase was significant after 3 years of planting; the soil C/N and C/P showed an increasing trend, compared with planting of one year, the 2 or 3 years’ planting increased C/N by 18.91% and 13.57 %, respectively, and C/P of 3 years’ planting increased by 14.71%, N/P had no significant change; (2) the activities of soil catalase, invertase, urease and alkaline phosphatase showed a U-shape change trend with the increase of planting years and the activities of soil invertase, urease and alkaline phosphatase had significant differences among the planting years; compared with one year planting, the activity of invertase of 2 and 3 years’ planting decreased by 49.71% and 38.79%, respectively, the activity of alkaline phosphatase decreased by 43.31% and 14.17%, respectively, and the activities of soil catalase decreased by 7.80% and 4.92%, respectively; the activity of urease of 2 years’ planting decreased by 17.17% compared with 1 year planting, while that of 3 years’ planting increased by 15.15%; (3) there was a continuous correlation between soil ecological stoichiometric characteristics and soil enzyme activity, the C/N was negatively correlated with soil enzyme activity and the C/P was negatively correlated with invertase and alkaline phosphatase; (4) the results of typical correlation analysis showed that the physical and chemical properties of soil had obvious effects on soil enzyme activities and the pH was negatively correlated with soil nutrient content. The research indicates that with the increase of continuous cropping years, the soil of Lanzhou lily shows an acidification trend, although short-term continuous cropping could provide good nutrient environment for Lanzhou lily, the nutrients tend to be out of balance. Therefore, in the management of lily farmland, attention should be paid to adjusting pH, reasonable fertilization, and balanced nutrients.

Key words: Lilium davidii var., continuous cropping obstacle, soil acidification, stoichiometric characteristics, enzyme activity, typical correlation analysis