Effects Of Multi-Functional Enviromnental Materials Ot Plant Growth And Soil Improvement In Semi-arid Region

Due to the climate and irrational human activities in semi-arid region,there have a series of problems such as sparse vegetation,water shortages,leading to Serious soil erosion and fragile ecological environment.Cold,dry,and soildepletion are three important features of this region,which prejudiced restoration of the vegetation and restricted forestry development.Therefore,applications of functional environmental materials and other technical methods maybe the best way to slove the problem.Based on the characteristics of environment in semi-arid region,polyacrylic acid super absorbent polymers and microbial fertilizer were chosen as soil conditioner.Soil improvement and plant growth were investagated in this study.Interaction mechanism of polyacrylic acid super absorbent polymers and microbial fertilizer were analyzed through the laboratoryexperiment.Influences of different mixed methods of polyacrylic acid super absorbent polymers and microbial fertilizer on plant growth(Pinus tabuliformis,Fraxinus chinensis,Syzygiumaromaticum,Swida alba,Medicago sativa and Festuca elata)and physicalandchemicalpropertiesofsoil were observed and compared in the field.Meanwhile,growth equation of Pinus sylvestris was used to evaluate the impact of soilconditioners on plant growth.Results showed that:(1)microbial fertilizer could significantly reduce water absorption rate of the super absorbent polymers,and then improve the degradation performance of super absorbent polymers.Microorganism activity of microbial agent in soil could be promoted by the concentration of super absorbent polymers,however high concentration of super absorbent polymers might inhibit the growth of microbial population.Super absorbent polymers significantly improved the soil moisture condition,but the microbial fertilizer slightly reduced the water absorption capacity of the super absorbent polymers in the soil.(2)Influences of different mixed methods of polyacrylic acid super absorbent polymers and microbial fertilizer on plant growth(Pinus tabuliformis,Fraxinus chinensis,Syzygium aromaticum,Swida alba,Medicago sativa and Festuca elata)and physical and chemical properties of soil were differences.Height and groud diameter significantly increased when there were polyacrylic acid super absorbent polymers and microbial fertilizer existed in soil.Meanwhile,ecological characteristics of roots were also impacted by polyacrylic acid super absorbent polymers and microbial fertilizer,which were reflected in ther increase of total root growth length,total root surface area and root length density.Medicago sativa showed the greatest biomass increment when there were low super absorbent polymers used in the experiment.When the concentration of super absorbent polymers was moderate,plant growth of Festuca elata reached the best situation.(3)The use of polyacrylic acid super absorbent polymers and microbial fertilizer was significantly increased the soil moisture content and soil water stability aggregates content.In addition,soil available nutrient,organic matter content,soil microbial biomass and microbial activity were also inproved to a certain extent.Soil moisture content and soil water stability aggregates content were increased with the concentration of super absorbent polymers.When there was microbial fertilizer existed in soil,soil water stability aggregates content might lower than no microbial fertilizer existed in soil,but higher than only microbial fertilizer used.In general,soil available nutrient and organic matter content of Pinus tabuliformis reached the best result when there were low super absorbent polymers existed in soil,for Fraxinus chinensis and Swida alba the best concentration of super absorbent polymers was moderate.There was no rule in of increment of soil microbial biomass and microbial activity in Syzygium aromaticum,Medicago sativa and Festuca elata with the concentration of super absorbent polymers and microbial fertilizer.Based in the results of principal component analysis,plant growth of Pinus tabuliformis,Fraxinus chinensis,Syzygium aromaticum,Swida alba,Medicago sativa and Festuca elata reached the highest when there were low and moderate super absorbent polymers and moderate microbial fertilizer used in the experiments.Beyond that,soil moisture content and soil water stability aggregates content also reached maximum.(4)In the field afforestation experiment in semi-arid area,multi-functional environmental materials significantly improved the survival rate,height,ground diameter and germination of the secondary tiller of Pinus sylvestris and Caragana intermedia.Soil water stability aggregates content,soil field capacity,maximum moisture absorption water content and effective water content were increased with concentration of super absorbent polymers,however,decreased with concentration of microbial fertilizer.At the same time,the environment material had promoted soil available nutrients and organic matter,and then increased soil microorganism amount,microbial carbon and nitrogen content,improved soil microbial environment and activity of microorganisms.According to principal component analysis,the best dosage of environment materials for growth of Pinus sylvestris and Caragana intermedia were moderate super absorbent polymers and high microbial fertilizer used in the experiments.(5)Based on the results of fitting curve of height and ground diameter,artificial forest growth model of Pinus svlvestris had been revised.Use of environmental materials advanced the fast-growing period of Pinus sylvestris and extended the length of the growth period.Predicted value of height and ground diameter of Pinus sylvestris at the age of 30 was higher than the value of those no soil conditioners used in the field.