| Northeast black soil area is an important commercial grain production base in China,but the long-term intensive production and unreasonable fertilization methods lead to the decline of soil production capacity,especially the utilization rate of chemical fertilizer is difficult to improve.How to improve the utilization rate and restore soil ecological function is a difficult problem to be solved for the sustainable development of agriculture and the protection of national food security.Therefore,in this experiment,pot planting was used to reduce the amount of chemical fertilizer and apply humic acid and decomposing agent.Taking the application amount of conventional chemical fertilizer（CF）as the control,under the condition of reducing the amount of chemical fertilizer by 50%（HF）and 25%（TF）,humic acid 0（A0）,250 mg·kg-1soil（A1）,500mg·kg-1soil（A2）,and decomposing agent 0（V0）were applied respectively 100 mg·kg-1soil（V1）was used to study the effects of different treatments on soil chemical and biological characteristics,maize growth and nutrient absorption,in order to provide reference for the establishment of stable yield,efficiency and environment-friendly optimal fertilization model of northeast black soil area.The results show that:1.Fertilizer reduction combined with humic acid and decomposing agent increased the number of soil fungi and bacteria in varying degrees,and there was a significant interaction effect.Among them,the number of soil fungi in Maize Jointing Stage and heading stage treated with hfa1v1 increased by 330%and 223.7%respectively compared with CFA0V0control.2.The activities of soil enzymes increased slightly under the condition of chemical fertilizer reduction,and the activities of soil urease,sucrase and phosphatase increased with the application of decomposing agent;The application of A1humic acid significantly increased the activity of soil humic enzyme;At the same time,the combination of decomposing agent and humic acid was lower than that of them alone.3.Fertilizer reduction combined with decomposing agent increased the content of soil available phosphorus,especially under TF treatment with 25%fertilizer reduction;Combined application of humic acid increased the contents of soil alkali hydrolyzable nitrogen and available phosphorus in varying degrees.The soil alkali hydrolyzable nitrogen in jointing stage,heading stage and mature stage of TFA2V0treatment increased by 53.1%,49.4% and 35.2%respectively compared with TFA0V0control;At the same time,the combined application of decomposing agent and humic acid significantly increased the available phosphorus content in heading stage and mature stage of maize,and TFA1V1treatment significantly increased 71.4%and 125.0%respectively compared with TFA0V0control.4.The reduction of chemical fertilizer combined with humic acid increased the contents of phosphorus and potassium in plants.The total phosphorus content of TFA1V0treatment increased by 35.4%,16.3%and 27.7%respectively,and the total potassium content increased by22.2%,16.5%and 17.5%respectively;The application of decomposing agent also significantly promoted the absorption of phosphorus and potassium in maize plants.The total phosphorus content in jointing stage,tasseling stage and mature stage of TFA0V1treatment increased by18.8%,12.9%and 84.2%respectively compared with TFA0V0control;At the same time,the effect of combined application of decomposing agent and humic acid was lower than that of combined application of humic acid.5.Fertilizer reduction combined with humic acid decreased the activity of enzymes related to plant carbon metabolism,but increased the sucrose content and soluble sugar content of TFA1V0treatment at jointing stage,which were significantly increased by 35.6%and 104.1%respectively compared with TFA0V0control,and the sucrose content at heading stage was significantly increased by 113.6%;The application of decomposing agent enhanced the activity of enzymes related to carbon metabolism,increased the content of soluble sugar at heading stage,but decreased the content of sucrose at each growth stage;The effect of fertilizer reduction combined with decomposing agent and humic acid is lower than that of them alone.6.The reduction of chemical fertilizer combined with humic acid increased the activity of enzymes related to nitrogen metabolism,Compared with TFA0V0control,the contents of nitrate reductase,glutamate synthase,glutamine synthase and soluble protein in Maize Treated with humic acid CFA0V0increased by 10.9%,27.9%,58.9%and 22.2%respectively,and the enzyme activity in heading stage increased by 23.8%,11.3%,20.8% and 71.0%respectively;The enzyme activities of Maize Treated with decomposition agent HFA0V1increased by 27.9%,39.9%,21.9%and 51.6%respectively;The effect of combined application of humic acid and decomposing agent is weaker than that of both alone.7.The reduced amount of chemical fertilizer combined with humic acid and decomposing agent enhanced the antioxidant enzyme activity of the plant and promoted the free radical scavenging ability of the plant,especially the enzyme activity of ascorbic acid glutathione circulatory system.At the same time,the combined application of humic acid and decomposing agent increased the antioxidant capacity of the plant to varying degrees,but the increase range was less than the effect of single application of humic acid and decomposing agent.Compared with CFA0V0control,the dry weight of mature plants treated with 25%reduction of chemical fertilizer and 100 mg·kg-1soil decomposing agent increased by 9.0%～15.6%,and TFA0V1treatment significantly increased by 15.6%;The dry weight of Mature Maize Treated with 50%reduction of chemical fertilizer and 100 mg·kg-1soil decomposing agent HFA0V1was significantly increased 10.2%higher than that of CFA0V0 control. |
