| Aiming at the problems that great amount of evaporation,drought and rainless,high groundwater and difficult improvement of soil in Jingyuan,Gansu Province.It focus on the research of groundwater dynamics and water-salt regulation in saline-alkali land on the basis of monitoring and analyzing the soil groundwater level and characteristics of soil water and salt transportation in the study area,combining field experiment.The research results can provide theoretical basis for the improvement of similar saline-alkali land in Gansu.The main findings are as follows:(1)The change of groundwater level during the year is greatly affected by irrigation.The maximum groundwater depth during the year occurred in late March,usually it is 1.7m?2.3m;the minimum groundwater depth during the year occurred in June and November,usually it is 0.7m?1.2m.The minimum value of groundwater salinity usually appears in April spring irrigation(#4 16.75g/L)and the maximum in July and November(#1 24.36 g/L).The groundwater depth is inversely proportional to the degree of mineralization.The linear relationship between the two is not obvious.The salinity of groundwater increases and the corresponding pH also increases during the year.The depth of groundwater has a suitable depth for different plants.The depth of groundwater in Malay should be under 1.2 m,the depth of groundwater in Tamarix is under 1.3?1.5 m,and the depth of groundwater in Amorpha + Malay is under 1.1?1.3 m,the depth of groundwater of 9901 Willow + Amorpha +Qrpin is under 1.5?1.7 m.(2)Drip irrigation can effectively regulate the distribution of water and salt by monitoring and analyzing.The salt movement in the experimental area during the year showed obvious seasonal dynamic changes,it is that soil return salt in spring,irrigation leaching desalination in summer and store salt under winter irrigation.Irrigation has a great influence on soil salinity,especially in 0-60cm soil layer.The greater the amount of irrigation,the more obvious effect of soil desalination.The change of salt content is small without irrigation treatment.The effect of increasing moisture content of lower soil is T3>T2>T1,but the effect of surface soil is T2>T3>T1.It is that the greater amount of the irrigation water,the greater increase of soil moisture content in lower soil.However,the surface soil is not.(3)Irrigation has a direct effect on plant growth and soil water and salt conditions,but it is not positive.Excessive irrigation may result in the plants' root system can not having normal life activities,so that alkaline ions and salt can not be completely absorbed by plants.Under the effect of the soil gradient potential,alkaline ions and salt move upward,so that they may congest in surface soils.Irrigation quota 2025 m3/hm2 is the best irrigation treatment of all kinds of models.Under this treatment,the indicators of plant growth are the best,soil pH?alkalinity and total salt decrease most significantly.This article studies the impact of different irrigation quantity on water and salt transportation and the effect of plants growth and water and salt transportation under the same model of arbor-shrub-grass,observes the dynamic changes of groundwater level continuously,and the relationship between groundwater and soil salinization was analyzed.It provides a scientific basis for the regulation of water and salt and the restoration of vegetation in similar saline soil. |
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