| The soil nitrogen mineralization rate is often used as an important indicator of soil nitrogen supply capacity.In order to analyze the relationship between soil nitrogen mineralization and mineral nitrogen and soil enzyme activities in different forest types,we select the Ligustrum lucidum?Koelreuteria Paniculata as well as Pterocarya stenoptera and Morus alba,Salix babylonica as the research object.The changes of mineral nitrogen content in soil mineral nitrogen during the growing season were determined by close-top incubation continuous method.The soil enzyme activity and soil physical and chemical properties of four kinds of forest land were analyzed and compared at the same time.The results are showed below:(1)The soil physical and chemical properties were different in the study area,and the soil organic matter and nitrogen content were as follows: Salix babylonica>Pterocarya stenoptera and Morus alba>Ligustrum lucidum>Koelreuteria paniculata.In the soil Profile,the indicators showed a vertical distribution of the law.(2)The content of ammonia nitrogen in soil was higher than that of nitrate nitrogen,and the ammonia nitrogen accounted for 69.2% of soil mineral nitrogen.The content of ammonia nitrogen in different stands showed the largest surface layer,and gradually decreased with the soil layer.The content of ammonia nitrogen in the surface soil of four forest stands was Pterocarya stenoptera and Morus alba> Salix babylonica>Ligustrum lucidum>Koelreuteria Paniculata.The contents of ammonia nitrogen and nitrate nitrogen in the surface soil of different forest tyPes showed a certain seasonal variation,which was relatively high in SePtember.and The change of ammonia nitrogen content in soil was consistent with the change of nitrate nitrogen content.(3)The seasonal dynamics of soil nitrogen mineralization in four kinds of standings showed that the soil ammonia and nitrification were similar,and the contents of the two reached the maximum in July and was significantly higher than that of other culture.The amount of ammonia and nitrification in the mixed forest soil were higher than those in other stands.During the growing season,the amount of ammoniation in the four soils was higher than that of nitrification.Soil nitrogen mineralization rate of Pterocarya stenoPtera and Morus alba>Salix babylonica>Ligustrum lucidum>Koelreuteria Paniculata,The trend of soil nitrification rate was similar to that of net mineralization rate,esPecially in the surface soil.The results showed that the soil nitrification rate was similar to that of the net mineralization rate.The net mineralization rate of the four soil layers is much higher than that of the net nitrification rate.The amount of soil ammoniation,nitrification and mineralization showed a decreasing trend with the soil layer.(4)The results showed that there were some differences in soil enzyme activities in different stands,and there were some differences in soil enzyme activity.The urease activity of each stand in the growing season is gradually increased,only in July there is a small reduction.The soil catalase invertase,Protease reached the highest value in July.Analysis of variance showed that there was a significant difference between Lingshu Lin,Luan Shulin and mixed forest and willow forest(P<0.01).Soil activity was the highest in the soil Profile,and the soil activity was the highest along the soil layer.There was a significant difference in soil enzyme activity between different soil layers(P<0.05).(5)The correlation analysis showed that there was a significant correlation between soil enzyme N mineralization rate,ammoniated amount and nitrification rate(P<0.05).Soil enzyme activity and soil nutrients have a certain correlation,which also shows that soil enzyme activity can be used to reflect the soil fertility.There was a significant correlation between N mineralization rate and soil nutrient(P<0.05),and had no significant correlation with soil water content and PH value(P>0.05). |
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