Study On The Contribution Of Plants To Soil Fertility Succession

In order to evaluate the vegetation contribution to the succession of soil fertility, this study made an analysis in a long-term location test to the soil in different patterns of land use in Lower-Liaohe plain tide brown earth district, and studied the changing pattern of the soil nutrient levels.In this paper, we conducted a comparative experiment on the content of the soil fertility variables among these three kinds of plots (i.e., Bare land, Cut grass land and Leisure land). We simulated the original way of plowing via the Cut grass land, and the Bare land and the Leisure land were used to simulate the changing process of the land coverage. We illustrated the changing trends of soil fertility in different patterns of land use and in different soil depths. The main conclusions were as follows:1) The growth of vegetation, the retention of vegetation coverage and root were beneficial for the increase of soil fertility and nutrient storage capacity. The succession of soil fertility was changed with years, the soil nutrient content showed that Leisure land>Cut grass land>Bare land. Besides, the soil nutrient content in the upper depth was greater than that of the lower depth.2) There existed significant difference in the upper soil nutrient (0-20 cm) among the different patterns of land use, e.g., the Alkaline hydrolysis nitrogen(N), available phosphorus(P), available potassium(K), total carbon(C), total nitrogen, total phosphorus. The soil nutrient content of the Leisure land was sharply increased, the Cut grass land showed an upward trend, and the Bare land was slightly decreased and even dropped to the lowest. There were no significant difference of total potassium and pH among the three patterns of land use. The microbial C and N in the Leisure land and the Cut grass land were alternately raised, while the Bare land showed the opposite trend.3) There existed significant difference in the lower soil nutrient (20-40cm) among the different patterns of land use, e.g.,the available P. While other nutrients such as the total N, Alkaline hydrolysis N and available K, has only little difference, and the general trend was Leisure land>Cut grass land>Bare land. As for total C, total P, total K and pH, there were no significant difference among three patterns of land use. But it also hold the trend that Leisure land>Cut grass land>Bare land.4)The preservation of natural vegetation was a process which kept the soil fertility accumulated. The Integrated Fertility Index (IFI) of the soil increased accompanied with the positive succession. The IFI in the Bare land, the Cut grass land and the Leisure land of 0-20 cm depth were 0.22,0.59 and 0.79, respectively; and the IFI in 20-40 cm depth were 0.24,0.28 and 0.32, respectively. The growth and reserve of natural vegetation was an effective way to improve the soil quality.Overall, there existed an increased trend of soil (preserved by vegetation) nutrient, during the succession process of soil fertility. That is to say, the root retention and vegetation coverage significantly promoted the soil nutrient content, which indicated that vegetation played an important role in the succession of soil fertility.