| In recent years, the purple soil fertility has been damaged in some part by all kinds of natural and human factors. As high quality organic fertilizer, legumes has good function in improving soil fertility. In this experiment, we use the legumes of Vicia villosa and Vicia faba for materials to explore the increase mechanism ofLegumeson dry land sloping purple soil. In order to improve purple soil fertility by growing legumes, This thesis focused on the following four aspects:improve Soil and water conservation capacity of dry land sloping purple soil and enhance the soil quality by planting leguminous legumes; The Activating effect of differentLegumesRoot exudates;The nutrient release characteristics of different leguminous egumes; The contributions to different purple soil microbial biomass carbon and nitrogen sources by PlowingLegumesthat marked. The main conclusions are as follows:(1) planting Vicia villosa on three purple soils can reduce runoff volume compared with planting Vicia faba. The amount of reducing on the acidic, alkaline and neutral purple soil are 8.36 m3/hm2、0.57 m3/hm、1.35 m3/hm2, After planting Vicia villosa and Vicia faba, the soil structure also changed. The soil bulk density were reduced 0.003 g/cm3,0.024 g/cm3,0.005 g/cm3,0.022 g/cm3,0.028 g/cm3,0.035 g/cm3. Porosity Increased as 5.28%,2.83%,4.79%,6.21%,3.68%,4.67%. Compared with planting Vicia villosa, the Effect of planting Vicia faba was more significant. Furthermore, planting legumes can improve Soil Fertility, Stimulate the growth of microbial. And Bacterial in the three most significant microbialtaxa is first, followed by actinomycetes, and fungi is small. compared with planting Vicia faba, the Effect of planting Vicia villosa is more significant on three purple soils.(2) The root exudates of different legumes can have a decreased effect on Alkali-hydro lyzable nitrogen content of different purple soils, but the effect is not the same, The Effect of root exudates of Vicia villosa is more significant on debasing Alkali-hydro lyzable nitrogen content of alkaline purple soil, the Effect of root exudates of Vicia faba is more significant on debasing Alkali-hydro lyzable nitrogen content of acidic purple soil. The root exudates of different legumes can have a increased effect on available phosphorus and available potassium content of different purple soils, but the effect is not the same. The Effect of root exudates of Vicia villosa is more significant on increasing available phosphorus content of acidic and alkaline purple soil, the Effect of root exudates of Vicia faba is more significant on increasing available phosphorus content of neutral purple soil. The effect of root exudates of Vicia villosa and Vicia faba all have a better activate effect on available potassium content of three different purple soils, compared with Vicia villosa, the Effect of Vicia faba is more significant. The root exudates of different legumes can have a decreased effect on soil pH of three different purple soils, the effect of root exudates of Vicia villosa is more significant on debasing soil pH of acidic and alkaline purple soil, the effect of root exudates of Vicia faba is more significant on debasing soil pH of neutral purple soil.The root exudates of different legumes can have a increased effect on soil available iron and available zinc content of three different purple soils, The effect of root exudates of Vicia villosa is more significant on increasing available iron content of acidic purple soil, the Effect of root exudates of Vicia faba is more significant on increasing available zinc content of neutral purple soil. Culturing three purple soils by root exudates, can promote the growth and reproduction of different levels of soil microbial community activity, compared with adding the root exudates of Vicia faba, the Effect of adding Vicia villosa is more significant on alkaline and neutral soil, but on acidic soil, the contrary is the case.(3)After applying Vicia villosa and Vicia faba the Cumulative decomposing rate are above 35%,40% in the first 14 days. When applying 84 days the Cumulative decomposing rate of Vicia villosa and Vicia faba are 57.63,58.23,61.87% and 58.6, 66.57,65.47%. Compared with the use of Vicia faba, the Effect of adding Vicia villosa is more significant, and two legumes appears first quick back slow trend. Compared with the use of Vicia villosa, the Effect of adding Vicia faba is more significant on three purple soils. The cumulative release rate of nitrogen, phosphorus and potassium of Vicia villosa and Vicia faba are above 70%,28%,87% and 72%,33%,85%. In the process of decay, two legumes appear first quick back slow trend of carbon-nitrogen ratio. After applying Vicia villosa and Vicia faba the carbon-nitrogen ratio are 21.35,21.8,19.44 and 17.45,21.03,18.11 in the first 14 days. When applying 84 days the carbon-nitrogen ratio of Vicia villosa and Vicia faba are14.08,14.78,13.86 and 11.89,12.59,12.2. Compared with the use of Vicia faba, the effect of adding Vicia villosa is more significant.(4) Two legumes appears first quick back slow and then stable trend of Microbial biomass carbon on three purple soils. After applying 28 days the microbial biomass carbon reached a maximum. Compared with the use of Vicia villosa, the Effect of using Vicia faba is more significant on acidic and neutral soil, but on alkaline soil, the contrary is the case. The marked Microbial biomass carbon appears the similar trend. Compared with the use of Vicia villosa, the Effect on marked Microbial biomass carbon of using Vicia faba is more significant. The marked microbial biomass nitrogen appears the similar trend with Microbial biomass nitrogen, two legumes appear first quick back slow and then stable trend on three purple soils. Compared with the use of Vicia faba, the effect of using Vicia villosa is more significant on acidic and alkaline soil, but on neutral soil, the contrary is the case. And compared with the use of Vicia faba, the effect on marked microbial biomass nitrogen of using Vicia villosa is more significant. The contents of microbial biomass carbon and nitrogen of two kinds of legumes treatment are higher than the control. Although the addition of exogenous substrates can bring new microbial nutrients and energy, but the original soil carbon and nitrogen are still the main source of soil microbial biomass carbon and nitrogen. |
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