Research On Soil Water And Salt Transport Patterns Of Agricultural Soils In Black Soil Areas Under Different Straw Mulch And Tillage Measures Based On HYDRUS Model

In order to reveal the influence mechanism of straw mulch and tillage measures on soil water and salt transport in the black soil region,this paper carried out field experiments on corn fields in the northeast black soil region,Six treatments including control（CK,traditional tillage without straw mulch）,traditional tillage with half straw mulch(CS_0.5,0.33 kg?m^-2),traditional tillage with full straw mulch(CS₁,0.65 kg?m^-2),no tillage without straw mulch（NK）,no tillage with half straw mulch(NS_0.5,0.33 kg?m^-2),and no tillage with full straw mulch(NS₁,0.65 kg?m^-2)were established,By measuring and simulating the information of soil water and salt during the whole growth period of maize in different treatments,the effects of different straw mulch amounts and tillage measures on soil water and salt transport were studied,in order to provide theoretical reference and basis for monitoring soil water and salt status and efficient and sustainable utilization of soil resources in farmland in black soil region.The main results are as follows:（1）The HYDRUS-1D model can simulate the process of soil water and salt transport under the experimental conditions.The average R²,RMSE and MRE of simulated and measured soil water and salt values under different straw cover and tillage measures are 0.919 and 0.837,0.012 cm³?cm^-3 and0.103 m S?cm^-1,4.21%and 4.90%,respectively,with high accuracy of model simulation.The simulation accuracy of soil water and salt in different soil layers is highest with CK treatment,and it increases with the increase of soil depth.Under the condition of straw mulch measures,the accuracy of soil water and salt simulation decreases with the increase of straw mulch;The simulation accuracy of soil water and salt under no tillage treatment is lower than that of traditional tillage treatment.Compared with soil moisture simulation,the accuracy of soil salinity simulation is lower.（2）The soil moisture content treated with different straw mulch and tillage measures showed a trend of first decreasing and then increasing with the passage of the growth period,reaching its maximum value in the mature period;As the depth of the soil layer increases,it gradually increases from the seedling stage to the jointing stage,and then decreases at the maturity stage.During the entire growth period of corn,there was a significant difference in soil moisture content between straw mulch and no tillage treatments compared to CK treatment（P<0.05）,both of which were higher than CK treatment,with an increase range of 0.21%to 14.48%,and increased with the increase of straw mulch.The soil moisture content of different soil layers at different growth stages is generally the highest under no tillage and full straw mulch treatment.Both straw mulch and no tillage measures can significantly increase the soil water storage capacity of corn at various growth stages,with an increase range of 2.59%to 16.05%.The soil moisture retention effect is most significant in the seedling and mature stages,respectively.The full straw mulch has a stronger water retention ability than other straw mulch treatments.（3）As the growth period progresses,the soil salt content decreases first and then increases under different straw mulch and tillage measures,reaching its minimum value during the jointing stage;As the depth of the soil layer increases,the soil salt content of each treatment first decreases and then increases during the seedling,tasseling,and grouting stages,gradually increases during the jointing stage,and shows a trend of first decreasing,then increasing,and then decreasing during the mature stage.Compared with CK treatment,straw mulch and no tillage measures can significantly reduce soil salt content at different growth stages of maize,with a reduction range of 0.53%to19.10%.As the amount of straw mulch increases,the impact of straw mulch measures on soil salt content becomes more apparent.The soil salt content in each growth period and soil layer is generally the lowest under the treatment of no tillage and full straw mulch.Straw covering and no tillage measures are mostly manifested as reducing the soil salt stratification ratio,slowing down the accumulation of soil salt into the 0-10 cm soil layer,and having the most significant impact on SR₁.