| Because the crude protein content and water content of Pennisetum Giganteum are2-3 times and 2 times that of common forage grasses,and have good palatability,it was first introduced into my country as a forage crop and a culture medium for planting and using fungi..In addition,Pennisetum Giganteum has the characteristics of developed root system,large number of tillers and strong stress resistance,and can improve soil nutrients,and has a certain enrichment effect on heavy metals such as Cu and Cd in soil.It is widely used in soil erosion control,soil improvement,etc.field.In this thesis,by sampling the soil before and after planting Pennisetum Giganteum in three different areas of Inner Mongolia,and tracing the soil for planting Pennisetum Giganteum to one meter of the excavation section,the soil physical and nutrient elements were measured,and the control group was set for comparative analysis.The results showed that :(1)Soil physical indexes were improved after planting Pennisetum Giganteum.The soil bulk density decreased by 9.00% and 8.39% respectively with the increase of time scale of planting Pennisetum Giganteum in Ulan Buhe Desert,Tumutzuo Banner and Naiman Banner.The maximum water holding capacity increased by 4.49,2.37 and 1.87 percentage points respectively;the field water holding capacity increased by 2.26,0.52 and 0.37 percentage points respectively,and the total porosity increased by 3.09,6.47 and4.75 percentage points respectively.And with the increase of planting time,the improvement effect of each physical index in the soil after Pennisetum Giganteum gradually increased.(2)There are differences in the improvement effects of nutrient indicators in different plots of Pennisetum Giganteum in different planting periods.With the increase of planting years,the contents of organic matter,total nitrogen,total phosphorus and total potassium in the three plots were increased respectively compared with the control.12.22%～22.86%,16.49%～56.73%,39.53%～79.68%,29.75%～51.24;alkaline hydrolysis,available phosphorus and available potassium increased by 24.75%～48.57%,60.07%～73.29%,11.67% respectively compared with the control %～117.10%.(3)In the improvement effect of Pennisetum Giganteum on the spatial distribution of soil nutrients,the vertical distribution of soil nutrients in each plot is as follows: with the increase of planting time,the soil nutrient content of each soil layer has been significantly improved.With the increase of soil depth,the content of soil organic matter showed a trend of first increase and then decrease.With the increase of soil depth,other nutrient indexes showed a decreasing trend in general and some soil layers fluctuated.The nutrient content of the lower 80～100 cm soil layer was similar to that of the bare land.The change rule of nutrient level is that the effect of soil improvement around the root system is stronger,and the improvement effect of available phosphorus is the highest.Different locations showed that the soil nutrient contents of the three plots under the same soil layer were rhizosphere>plant margin>interplant.The overall improvement effect of Pennisetum Giganteum on the spatial distribution of soil nutrients showed a law that gradually decreased with the increase of soil depth,and weakened in the direction away from the rhizosphere.(4)In different planting time,there are differences in the degree of influence on each physical and chemical property index in the soil.Planting Pennisetum Giganteum in Tumotzuo Banner and Naiman Banner has the highest soil improvement benefits.Further research and optimization of improvement techniques are required for Ulanbu and desert improvement,including comprehensive management of intercropping with other plants and improvement of planting row spacing. |
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