| Aiming at the problems of poor water retaining capacity and difficult vegetation growth of coal gangue land reclamation soil,combined with the characteristics of Ningxia's arid climate,studied on soil moisture dynamics and Symphytum officinale L.growth of coal gangue reclamation soil with different overburden texture(S1:sand?S2:loam)and overburden thickness(H1:20?40 cm?H2:40?60 cm?H3:60?80 cm?H4:80-100 cm).Through carrying out indoor infiltration simulation test and field test,monitoring the characteristics of water infiltration,moisture content,nutrient content and growth of Symphytum officinale L.in the reclaimed soil under different overburden modes,and to study the effect of cover soil texture and thickness on the reclaimed soil water dynamics and the growth of Symphytum officinale L.,Therefore,the best soil covering mode of the coal gangue landfill site is selected,which provides a scientific basis for further standardizing the reclamation of coal gangue site in this area.The main result are as follows.(1)The coal gangue interlayer inhibits the process of soil moisture infiltration and increases the soil moisture content of the upper layer of coal gangue during the initial irrigation period.At the end of the infiltration simulation test,the moisture content of the upper layer soil increased by 2.58%and 2.94%compared with the control soil under the condition of sand and loam soils overburden.However,due to the low water conductivity of coal gangue and the presence of capillary barriers between the soil layers,it is difficult to recharge groundwater.Under evaporation,the upper soil moisture continues to decrease but it is difficult to replenish,resulting in poor drought resistance of the reclaimed soil,16 days after irrigation,the water content of the reclaimed soil decreased by an average of 10.58%compared with the control soil,and the water content of the reclaimed soil decreased by 10.58%on the 16th day after irrigation compared with the control soil.(2)The volume density of reclaimed soil decreased first and then increased with the increase of cover thickness,and it was the smallest whenthe soil cover model S2H3,which was1.54 g·cm-3.The content of organic matter first increased and then decreased with the increase of the thickness of the cover soil,and the content of organic matter covered by S2H3 type soil is the highest,which was 7.63 g·kg-1.The content of soil available nitrogen and potassium basically increases with the increase of the thickness of cover soil,but the content of available phosphorus has no obvious trend with the change of the thickness of cover soil.The physical and chemical properties of reclaimed soil are influenced by different types of soil cover mainly through their soil structure characteristics and nutrient status.(3)The growth of Symphytum officinale L.in the reclaimed soil is worse than that of the control soil,and the thickness of the cover soil has a greater impact on the growth of the Symphytum officinale L.in the reclaimed soil than the texture of the cover soil.The thin cover soil is not conducive to the growth and development of Symphytum officinale L.,In the reclaimed soil,the maximum leaf length of S2H3 Symphytum officinale L.is 23.12 cm,the total dry matter is 49.83 g,and the root length is 27.53 cm.The reclaimed soil has the best growth condition of Symphytum officinale L..Combined with the physical and chemical properties of reclaimed soil,S2H3 is selected as the best soil cover method for the reclaimed site.In this paper,throughout indoor infiltration simulation test and coal gangue reclamation site test,the soil moisture movement law of coal gangue landfill was clarified,the best soil covering mode of the coal gangue landfill site is selected,which provides a scientific basis for further standardizing the reclamation of coal gangue site in this area. |
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