Salt-Water Dynamic And Regulation Of Saline-Alkali Alfalfa Artificial Grassland

Grasslands of western Songnen plain are suiteable for mechanized-graziery in this region due to the the water and temperature conditions which influences by Pacific monsoon climate and the flat terrain.Moreover,influenced by the high plant coverage and diversity,black soil was developped,and the high qulity-forgae species was dominated by Leymus chinensis in this western Songnen plain.However,the fragile and sensitive ecoenvironment of western Songnen plain could be impacted by the high salinity groundwater,parent material,and the special position.For the reason of overgrazing and overdevelopment,the grasslands in western Songnen plain were significantly salinized and degradated.The livestock huabandry was remarkable hindered by the poor grassland productivity.Thus,an artificial grassland was seleted for the aims of detecting spatial characteristic of soil,regulation of soil-water dynamics,critical salt and water concentration for nomal development of alfalfa and the irrigation scheduling that suits for saline-alkali artificial grasslands in western Songnen plain,northeastern China.The results of our research indicated that 1)The strong spatial variance of soil electrical conductivity?EC?and soil total alkalization?TA?were significantly depended by climate and parent material;in addition,the moderate spatial variance of soil pH and soil mass water content were impacted by structure and random factors.2)The dry yield of saline-alkali artificial grassland could be predicted by soil pH with Y?DM?=2699.73-276.496 pH?R²=0.403,7.17<pH<9.92?,which also indicate that the upper limitation of soil pH for alfalfa is9.92;3)The highest volumetric water content,at depth of 0¹00 cm,was observed at moderate saline-alkali artificial grassland;furthermore,the soil pH and SAR of saline-alkali artificial grassland?depth of 0¹00 cm?decreased followed the growth time compared with the soil EC and TA at depth of 0¹00 cm of mild and severe saline-alkali aritifical grassland.4)The growth rate of alfalfa and artificial grassland productivity were diminished by the increase of soil salinity.4)Branching period is more sensitive to the water deficiency compares to the regreen and flower periods of alfalfa.There will be significantly dry weight reduction of aflfalfa when water deficiency ocurrs to alfalfa.5)The water use efficiency?WUE?will increase by irrigation significantly;in addition,the WUE of I5 was highest among the eight irrigation treatments,and then follows the I1 treatment.6)10%of the volumetric water content?depth of 0¹00 cm?of saline-alkali artificial grassland was promoted by irrigation;in addition,the soil EC,SAR and TA were decreased at 182³45?S cm^-1?8.95⁹.00?mmol_c/L?^1/2,and 3.29⁴.65 mmol_c L^-1 by irrigation,respectively.7)The WUE of alfalfa could be promoted by irrigation,and the highest WUE was observed at I5 treatment that irrigated at branch stage of alfalfa.8)Considering the climate characteristics,underground water properties and soil salinity degree of western Songnen plain,irrigation at branch stage of alfalfa is recommend in western Songnen plain for pursuing relative forage yield.Moreover,the feasible irrigation quota depends on the evapotranspiration of western Songnen plain.