The Effects Of Land Use On Physic-chemical Property And Enzymatic Activities In The Soil Of Nandagang Wetland

In this article, spatial distribution and changing rules of several physical and chemical factors and activities of enzymes in soil of Nandagang wetland were analyzed. Physical and chemical factors included pH value of soil, organic matter, total nitrogen, nitrate nitrogen, ammonium nitrogen and total phosphorus while enzymes included invertase, proteinase, alkaline phosphatasein, dehydrogenase and FDA hydrolysis. Interactions between physic-chamical factors and soil enzyme activities and the effects of land use upon them were also studied. These practices helped to find effects of land use upon physical and chemical characteristics and enzymes activity of wetland's soil, and played important role to protect and utilize of salt mashes including Nandagang and other wetland. Main results of research are followed:1. The effects of land use upon physical and chemical characteristics of wetland's soilBy depth changing, soil pH values in all sampling points mainly increased, organic matter, total nitrogen, nitrate nitrogen and total phosphorus contents decreased. The maximum appeared in the surface or subsurface. Amount of ammonium nitrogen fluctuated. In detail, pH value in reed soil first increased and then decreased, and total phosphorus showed a special upward trend. Comparing with other sampling points, soil pH values in cotton field and corn field were lower, while organic matter, total nitrogen , nitrate nitrogen, ammonium nitrogen and total phosphorus contents had a higher level. The sampling point in reeds of the core area had the highest total phosphorus level, and in alfalfa had a high nitrate nitrogen level, but other nutrients of them were low. Besides, nutrient level of the reeds area was not high. This result showed farming on the Nandagang wetland could decrease pH value of the soil while fertilizing it.2. The effect of different land use upon enzyme activity of wetland's soilThe activities of 5 kinds of enzymes, invertase, proteinase, alkaline phosphatasein, dehydrogenase and FDA hydrolysis, were downward with the changes of the depth at all sampling points, and the maximum appeared in the surface or subsurface. But the sampling point in corn field showed different results, the activity of proteinase and alkaline phosphatasein is upward at first, then downward. Comparing with other sampling points, soil enzyme activity from sampling points in cotton field and corn field had different trends, activity of alkaline phosphatase, dehydrogenase and FDA hydrolysis activities were higher, and invertase was lower, while proteinase of a mean level. This result showed farming could improve enzyme activities and meliorate soil quality.The whole investigation showed sampling points in cotton field and corn field had better fertility, indicating soil of Nandagang wetland could be effectively improved by farming. Fertilizing this marshland by using the method mentioned above properly, local people's incoming would be increased while local environment protected.