Effects of different fertilization patterns on soil enzyme activities during growing period of autumn-winter season celery in greenhouse

【Objectives】 The fixed-site greenhouse vegetable fertilization experiment is in Tianjin, where the rotation of tomato in spring season and celery in autumn-winter season has been set up. The effect of different fertilization patterns on soil enzymes activities was investigated to provide a scientific fertilization basis for sustainable and high-efficient vegetable production in greenhouse. 【Methods】 The experiment was carried out on celery in autumn-winter season, including 6 treatments depending on the proportion of nitrogen from different types of fertilizers: 1) Complete chemical nitrogen fertilizer (4/4CN); 2) 3/4 N from chemical fertilizer, 1/4 from pig manure (3/4CN+1/4PN); 3) 2/4 N from chemical fertilizer, 2/4 from pig manure (2/4CN+2/4PN); 4) 1/4 N from chemical fertilizer, 3/4 from pig manure (1/4CN+3/4PN); 5) 2/4 N from chemical fertilizer, 1/4 from pig manure and 1/4 from straw (2/4CN+1/4PN+1/4SN); 6) 2/4 N from chemical fertilizer, 2/4 from straw (2/4CN+2/4SN). This investigation was conducted in the ninth harvest of celery. All the treatments were applied with the same amounts of N, P2O5 and K2O nutrients. 0-20 cm surface soil samples were collected. Soil enzyme activities, includiung soil α-glucosidase, β-xylosidase, β-glucosidase, β-cellobiosidase, chitinase, phosphatase and urease were measured at different growing stages of celery, and their correlations with contents of MBC, MBN, DOC and DON were calculated.【Results】 Activities of soil α-glucosidase, β-xylosidase, β-glucosidase, β-cellobiosidase, chitinase and phosphatase in different treatments all increased initially and then decreased, with relatively higher activity at 60-90 days after transplanting of celery. Soil urease activities increased gradually during the celery growing season. Compared with the 4/4CN treatment, activities of soil α-glucosidase, β-xylosidase, β-glucosidase, β-cellobiosidase, chitinase, phosphatase and urease were increased by 22.9%-92.0%, 20.1%-152.4%, 23.1%-145.1%, 28.7%-273.8%, 9.2%-207.8%, 13.7%-86.8% and 6.5%-56.5%, respectively in treatments with combined application of manure and straw with chemical fertilizers, and by 59.9%-92.0%, 98.9%-152.4%, 90.3%-145.1%, 171.6%-273.8%, 106.4%-207.8%, 68.8%-86.8% and 30.7%-56.5%, respectively in straw-amended treatments. Significant positive correlation relationships were found between enzymes activities and contents of MBC, MBN, DOC and DON and celery yield. 【Conclusions】 Compared with the 4/4CN, combined application of chemical fertilizers with organic materials, especially corn straw, can greatly enhance soil enzymes activities in greenhouse vegetable field. Soil enzymes activities are significantly correlated with MBC, MBN, DOC and DON contents and vegetable yield. Therefore, the combined utilization of organic and inorganic fertilizers can significantly increase soil enzymes activities, and maintain soil fertility in greenhouse vegetable production.