The Effect Of Different Soil Improvers Applying In Typical Irrigation Area On The Soil Water Movement Mechanism And Crop Growth Characteristics

Hetao Irrigation District is located in the middle reaches of Yellow River and in the territory of Bayannur Meng of Inner Mongolia Autonomous Region,which is one of three large-scale irrigation area in China.With the China gradually to water-saving economic transformation,one of significant problem to the agricultural modernization is how to improve the irrigation system and control measures through new technologies and new materials and how to improve the efficiency of water utilization in arid and semi-arid areas.Facing for the salinization and the losses by evaporation and seepage,under the ensuring of crop yield condition,one focal point of soil research is how to reduce the loss of agricultural water consumption and to avoid the soil salinization.Soil amendments application is one of the feasible measures to improve the soil physical and chemical properties and improve the soil water holding capacity.In this paper,using super absorbent polymers(SAP)and straw biochar(Straw Biochar)as a soil conditioner,it is study soil infiltration,soil evaporation,soil water and salt transport,soil aggregates,and crop growth and yield index and other aspects from the field soil investigation and soil column simulation experiment.And it would be expected to improve efficiency of irrigation water utilization and provide a theoretical basis for cultivated soil.The research results are as follows:(1)According to the analysis of soil column simulation and field experiment,it studied the effect of soil amendments on soil infiltration capacity.The results show that both SAP and biochar could improve the soil infiltration capacity in study area,but mechanisms of their infiltration rate and cumulative infiltration are significantly different.And compared to SAP,biochar exert more ideal infiltration capacity in the field experiments.The increase rate of surface soil infiltration was between 45.45 to 56.82%,and cumulative infiltration volume increased by 37.6%to 44.6%.(2)Under the simulated evaporation condition and field evaporation condition,it studied the effects of two kinds of soil amendments on soil evaporation process.The results show that both soil amendments could restrain soil evaporation,but the biochar can delay more soil water evaporation.In biochar field test,the cumulative evaporation were less than CK 9.58%(Bo-10),6.28%(Bo-20),10.95%(Bo-30)and 4.2%(Bo-50);and biochar can slow down decreasing from the high soil water content to field capacity;and according to night moisture data of 3 continuous monitoring days of each growth period,biochar can also increase the water content in daily night by transporting water from lower soil to upward,the recharge at seedling stage is up to 18.52%to 79.62%,jointing stage up to 55.81%to 202.38%,and tasseling stage reached 270.83%to 587.5%and the mature period is up to 6.66%to 61.64%.(3)According to the result of field monitoring and soil column simulation experiment,it studied dynamic changes of soil ameliorants before and after applying amendments.We found that two kinds of soil amendments played a certain effect on soil anti salt.The group of SAP performance as inhibit salt effect on Maize Seedling and jointing stage,and it began gradually to accumulate salt from the jointing stage;but biochar can restrain anti salt effect on the whole growth period of corn,and it began to accumulate salt only in the mature period.The biochar could increase the concentration of Ca,Mg and K in soil and promoted the nutrient absorption and the photosynthesis of crops.(4)Because of inorganic fertilizer application,soil structure and soil fertilizer was damaged and reduced in Hetao irrigation area.In order to unravel this problem,it studied soil aggregates and soil water stable aggregates,and soil structure changes of soil ameliorants before and after applying amendments.From the overall trend,two kinds of modifiers all could increase the soil water stable aggregates content.In the surface layer(0-15 cm),the larger water stable aggregates decreased,and micro aggregates content increased with particle size decreasing.While in the second layer(15～30 cm),water stable aggregates were significantly increased,SAP treatments S-3,S-6,S-9 and S-12,compared to CK,increased respectively by 159,3%,132.3%,134.5%,168.1%,and the biochar treatments Bo-10,Bo-20,Bo-30 and Bo-50 increased respectively by 75.6%,78.24%,143.2%and 74.22%.And other size showed different degrees of decrease and increasing gradually with biochar application amount increasing,but the difference was not significant.According to the linear regression relation between the water retaining agent and GMD(Waterstable geometric mean diameter),when the dosage of SAP reached 86.66 kg/hm2,water stable aggregate reached the maximum size.Biochar has obvious effect on soil organic matter content,and trend of organic matter content in different performance levels is Bo-50>Bo-30>Bo-20>Bo-10>CK;the organic content changing in the depth direction is as follows:0～15 cm>15～30 cm>30～60 cm.According to the 3D surface relationship of biochar,GMD and organic matter content,when biochar application amount reached 29.38 t/hm2 the soil aggregate size reaches the maximum,compared to CK,the organic matter content increased by 25.71%.(5)Using the monitoring data of the main meteorological factors affecting the growth of maize and physiological index and yield of maize in crop growth period,it studied the specific effect of two kinds of modifiers on soil temperature,photosynthetic rate,and growth index of maize etc..The results showed that:two kinds of modifiers on the soil surface(0～20 cm)temperature played a role of insulation,but during the whole growth period of Maize,biochar treatment could be more efficient than SAP to defense soil surface temperature changing.The soil temperature of Bo-30 and Bo-50 was higher than CK,and the temperature range respectively:-0.98～0.72 degrees and 0.82～2.17 degrees.Both SAP and biochar could promot Maize Photosynthetic rate,and early stage,promotion effect of biochar group on leaf photosynthetic rate is more obvious.SAP and biochar all could increase the maize kernel number per row,the row number,100 grain weight and yield,and biochar was more stable and had maximum yield,reached 11.88%(16131.21 kg/hm)compared to CK.Therefore,biochar had better improve effect on the soil in the study area,and also had advantages of saving water,improving soil fertilizer and increasing yield.