Effects of long-term combined application of fungus residue and chemical fertilizer on soil enzyme activities in paddy field

Abstract

Objective The purpose of this study is to explore the effects of different proportions of fungus residue and chemical fertilizer on soil enzyme activities during the rice growth period over a long-term scale. Method A long-term location experiment in paddy field was carried out in which the fertilizer levels were set as 0% (C0), 50% (C50) and 100% (C100) of conventional fertilization amount, and the relative amount of edible fungus residue was set as 0% (F0), 50% (F50) and 100% (F100), respectively. There were 9 treatments in total. The changes of catalase, sucrase and urease activities in different treatments at the main growth stages of rice and the interaction effect of fungus residue and chemical fertilizer on soil enzyme activities were analyzed. Result The soil enzyme activities showed obvious regularity with the change of rice growth period. The catalase, sucrase, and urease activities were 3.01−10.20 mL·g−1, 0.20−2.04 mg·g−1, and 0.54−4.80 mg·g−1 respectively. There were significant differences (P＜0.05) in soil catalase, sucrase and urease among the treatments in different growth stages of rice. The results showed that the combined application of fungus residue and chemical fertilizer promoted the soil urease activity in the early stage of rice transplanting, and enhanced the activities of catalase and sucrase in the filling stage and harvest stage. The activities of catalase and urease were the highest in C100F50 treatment, while the sucrase activity was the highest in C50F100 treatment. Path analysis showed that available phosphorus, alkali hydrolyzed nitrogen and total nitrogen had the greatest impact on catalase, sucrase and urease respectively, with path coefficients of 0.69, 1.80, 0.69 respectively. The combined application of fungus residue and chemical fertilizer promoted soil enzyme activity mainly by increasing the mass fraction of alkali hydrolyzed nitrogen. Interaction analysis showed that the effect of combined application of fungus residue and chemical fertilizer was higher than that of chemical fertilizer and fungal residue alone, and the activities of catalase, sucrase and urease in soil were significantly affected (P＜0.05). Conclusion The combined application of fungus residue and chemical fertilizer can significantly increase the activities of soil catalase, sucrase and urease, but with the increase of application amount, the activity of soil catalase, sucrase and urease increases first and then decreases. C100F50 treatment is the optimal choice to improve soil enzyme activity and promote carbon and nitrogen cycle under the experimental condition. [Ch, 1 fig. 4 tab. 38 ref.]