Influence Of Exogenous Organic Carbon On The Properties Of Salinization Soil And Wheat Growth

In recent years,biochar has been gradually concerned due to its ability to improve the quality of degraded soils.Because of low annual rainfall and large evaporation,the problem of soil salinization in arid and semi-arid regions has severely constrained the sustainable development of the ecological environment and agricultural activities in Gansu China.It is of great scientific significance to explore the amendment method and mechanism of biochar to salinized soil and to the development and utilization of salinized soil in arid and semi-arid regions.In order to detect the influence mechanisms of different types of exogenous organic carbon on the properties of mildly,moderately,and heavily salinized soils and wheat growth,he characteristics of chemical properties,biological characteristics and wheat growth were investigated in salinization soil.The control incubation experiment and pot experiments were used in a climate growth chamber.The results indicated that1.The electric conductivity?Ec?of soil were reduced under the addition of exogenous organic carbon in 3 degrees of salinization soil,and it was the most significant reduction in heavily salinized soil,while the 6%application rate was reduced more than the 3%application rate.Compared with the 4 kinds of exogenous organic carbon,the negative effects of glucose and starch on soil electrical conductivity were greater than those of biochar and humic acid.The content of Na⁺and Cl^-was reduced under the 4 types of exogenous organic carbon treatments in 3 degrees of salinization soils,and the addition of 6%carbon was more effective than the addition of 3%carbon.The contents of Ca²⁺and K⁺were increased in 3 different degrees of salinization soils under the 4 types of exogenous organic carbon treatments,the Ca²⁺content increased more at 3%,and the K⁺content increased better at 6%.2.The content of soil organic carbon?SOC?was increased under the addition of glucose,starch,biochar and humic acid in 3 different degrees of salinized soil,and it was increased more with 6%addition amount.In addition,soil SOC increased most significantly under glucose addition.There was a significant positive correlation between soil microbial biomass carbon?SMBC?and soil SOC in all 3 salinization soils.The effects of 4 kinds of exogenous organic carbon on increasing soil microbial biomass carbon content were as follows:glucose>starch>biochar>humic acid;exogenous organic carbon added promoted soil respiration,and glucose and starch addition treatment had the largest increase.The promotion effect on soil respiration was lower at the 6%addition level than at the 3%addition level,and the effect on the respiration of severe salinization soil was lower mild and moderate salinized soils exhibit hysteresis.3.The activities of fluorescein diacetate hydrolyzing enzymes?FDA?,?-glucosidase?PAG?and dehydrogenase?DHA?in the 3 different degrees of salinized soil after the addition of 4 various of exogenous organic carbon were all increased.Under the treatment of glucose and starch addition,FDA enzyme and?-glucosidase activity increased significantly by 72.9%-371.0%and 23.0%-213.7%,respectively.Dehydrogenase activity was greatly influenced by the addition of exogenous organic carbon.Urease?UA?activity is greatly affected by the degree of soil salinization.The?-glucosidase?PAG?and dehydrogenase?DHA?enzymatic activity associated with the C cycle in salinized soils was significantly enhanced by the addition of exogenous organic carbon.Soil urease activity was inhibited by the addition of exogenous organic carbon.4.The growth of wheat was improved under 4 types of exogenous organic carbon treatments in 3 different degrees of salinized soil,and the dry weight,survival rate,root length and root surface area of wheat increased significantly.The content of Na⁺and Cl^-of the aboveground of wheat seedlings were increased in moderately and heavily salinized soils under 4 types of exogenous organic carbon,and the content of Na⁺and Cl^-was reduced more with 6%addition than with 3%addition.However,after the addition of exogenous organic carbon,the content of Na⁺in shoots of wheat was increased in mildly salinized soil.The K⁺content of wheat shoots increased with the addition of exogenous organic carbon,and 6%increased more than 3%.Overall,the order of improving effect of exogenous organic carbon on wheat growth was:glucose>starch>biochar>humic acid.