Study On Soil Ecological Improvement Demonstration In Coastal Newly-reclaimed Land Based On The Synergy Of Restoration And Production

The exploitation and utilization of coastal land resources is an important way to solve the city’s land utilization dilemma.In order to relieve the existing problems of coastal newly-reclaimed land in Chongming Hengsha,which are poor structure,low fertility,and easy to salinize,this paper proposed an integrated treatment of "Organic fertilizer improves soil structure + Microbial agents restores soil activity + Planting rice to wash and discharge salt ".Field experiments were conducted to study the influences on soil physical and chemical properties,soil microorganisms,rice production,and to analyze the effects of soil ecological restoration and fertility improvement on the newly-reclaimed land,aiming at providing solutions for soil quality improvement in coastal newly-reclaimed land and efficient agricultural utilization of coastal land resources.The main findings are as follows.(1)The integrated treatments improved soil physical and chemical properties.The p H of soil in the experimental fields decreased by 0.03 ～ 0.27,and electrical conductivity dropped by 15.4 ～ 47.5%.The content of soil organic matter tended to increase at first and then followed by decreasing.The organic matter content of the experimental fields mostly increased by 66.7% than the initial value.Compared with the control,the contents of available N,P,K of soil in the experimental fields were increased by 10.2 ～ 32.5%,26.1 ～ 71.9%,18.1 ～ 32.1%,respectively.Soil aggregates in the control and the experimental fields with organic fertilizer were mainly composed by small-particle aggregates(<0.25mm),accounting for 44.4% and 33.7%,respectively.Organic fertilizer + Microbial agents promoted the transformation of soil aggregates from small particles to large particles,reducing the proportion of <0.25 mm while increasing 0.25 ～ 0.5mm,3 ～ 5mm and > 5 mm particles.(2)The integrated treatments promoted the recovery of microorganisms and the increase of soil enzyme activities.The urease,sucrase and alkaline phosphatase activities of soil in the experimental fields were 1.39 ～ 2.14,0.89 ～ 2.48,1.79 ～ 2.28 times that of the control,with the microbial biomass carbon increasing by 5.0 ～54.2% simultaneously.The integrated treatments improved the relative abundance of Proteobacteria,Bacteroidetes and Actinobacteria,as well as the functional groups of chemoheterotrophy,aerobic chemoheterotrophy,fermentation,nitrogen fixation and ureolysis.Among them,the relative abundance of the functional groups of chemoheterotrophy and aerobic chemoheterotrophy were significantly positively correlated with the sucrase and alkaline phosphatase activities,also the contents of available P,N(p < 0.05),indicating the improved capacity of nutrient transformation.(3)The integrated treatments also promoted rice growth and yield.The length of roots,height of plants,SPAD of leaves and dry matter of rice in the experimental fields were significantly higher than those in control,especially the height of plant increased by 17.02±10.43 cm/plant,the dry matter of leaves and panicles increased by9.18±4.83 g/plant,20.66±9.24g/plant,respectively.Compared with the control,the yields of the experimental fields were increased by 16.3 ～ 129.1%,and the partial factor productivity(PFP)of N,P,K fertilizers were also improved.Bacteroidetes,Firmicutes,Actinobacteria and the functional groups of chemoheterotrophy,aerobic chemoheterotrophy may promote rice growth and nutrient accumulation(p < 0.05).The heavy metal contents of dehulled rice grains in all treatments is lower than the national food safety standard limitation(GB2762-2017),without heavy metal pollution risks.Sensory evaluation results showed the appearance,palatability,and taste of the rice produced by the experimental fields were better than those in control.