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【Objective】 Organic fertilization and soil conditioner have been found capable of improving soil structure and enzymatic activity. The aim of this paper is to study how organic fertilizer and soil conditioner combine to regulate bioavailable nitrogen (N) and the yield of greenhouse tomato. 【Method】 The experiment was conducted in a solar greenhouse. It comprised five treatments: no fertilization (CK), chemical fertilization only (H), organic fertilization only (Y), 50% chemical N fertilizer and 50% organic (N) fertilizer (HY), 50% chemical N fertilizer + 50% organic N fertilizer + soil conditioner (HYG). In each treatment, we measured the change in mineral N, total N, N in microbial biomass, urease and nitrate reductase activity, and the tomato yield. 【Result】 Compared with CK, all fertilization treatments increased ammonium and nitrate in soil significantly, regardless of the growth stage. At harvest stage, HY increased total soil N and N in microbial biomass by 125.07%~204.22% and 289.20%~398.04% respectively, compared to those in the CK, 53.45%~79.80% and 133.74%~271.32%, respectively, compared with those in H. In all treatments, urease activity in the 0~20 cm soil peaked at the one ear fruit stage, while soil urease activity in the 20~40 cm soil maximized at the harvest stage. HY significantly increased nitrate reductase activity in the soil which peaked at the full fruit stage. Among all fertilization treatments, the activity of urease and nitrate reductase was maximum in Y and the least in CK. Compared with CK, all fertilizations increased tomato yield at significant level, with the yield increase ranging between 11.05% and 38.18%. Compared with H, HYG increased the yield by 38.18%. 【Conclusion】 Combination of 50% chemical N fertilizer and 50% organic N fertilizer reduced the costs but increased soil fertility and tomato yield without increasing N loss. It can then be used as an improved agronomic management for greenhouse tomato production. |
