Effects Of Simulated Acid Rain And Litter Of Cryptomeria Fortunei On Soil Nutrients And Soil Microorganisms

In order to make clear the effects of acid rain stress and litter on the content of soil nutrients andthe quantity of soil microorganisms, we analyzed the content of soil nutrient and the quantity of soilmicroorganisms in rhizosphere soil of Cryptomeria fortunei seedling under the simulated acid rain(pH3.0,4.0,5.6) and litter (400,500,600g·m-2), as well as combined of simulated acid rain and litter.The main results showed that:(1) The contents of soil exchangeable H+and exchangeable Al3+was increased on simulated acidrain, the increasing extent is pH3.0> pH4.0> pH5.6, however, The contents of soil exchangeable H+and exchangeable Al3+was declined with the increasing of litter cumulant. Litter processed soilcombined with acid rain had no significant effect on the contents of soil exchangeable H+. The contentsof soil exchangeable Al3+was only increased significantly (P <0.05) under the pH4.0+L-400、pH4.0+L-500、pH3.0+L-400、pH3.0+L-500and pH3.0+L-600treatments.(2) The contents of soil nitrogen, phosphorus, and potassium and the quantity of bacteria andactinomyces were decreased under the acid rain treatment, whereas the number of fungi was increased.The influence extent was pH3.0> pH4.0> pH5.6. The change of the content of soil total nitrogen,available nitrogen, total phosphorus, and available phosphorus and the quantity of microorganisms weresignificantly under the pH4.0and pH3.0treatments. The content of total potassium and availablepotassium were declined under pH3.0treatments.(3) The content of soil nitrogen, phosphorus and potassium and the quantity of microorganisms were increased with the increasing of the weight of litter. The content of soil nitrogen wasincreased by24.1%(P <0.01) under the L-600treatment. The litter treatment had significanteffect on the content of soil available nitrogen, but had no significant on the content of totalphosphorus. The content of soil available phosphorus was increased by13.6%and15.3%(P<0.05) under the L-500and L-600treatments, and the content of total potassium was increasedby22.9%and29.6%(P <0.01), respectively. The content of soil available potassium wassignificantly influenced by litter treatment.(4) When the pH value was same, the content of soil nutrient and the quantity of microorganisms were increased with the increasing of litter. When the litter treatment was same, the content of soil nitrogen, phosphorus, and potassium and the quantity of bacteria and actinomyces weredecreased with the decreasing of pH value, however, the quantity of fungi was increased with thedecreasing of pH value.(5) The principal component analysis was applied for the study of soil characters, and two principalcomponents which accounted for87.9%accumulation contribution. Comprehensive evaluation showedthat the L-600treatment had significant effects on the content of soil nutrient and the quantity ofmicroorganisms. The results of cluster showed that the samples could be clustered reasonably into threegroups, and the treatments were related to the soil characters.In summary, the content of soil nitrogen, phosphorus, and potassium and the quantity of bacteriaand actinomyces were decreased with the decreasing of pH value, whereas the number of fungi wasincreased. The content of soil nutrient and the quantity of microorganisms were increased under thelitter treatments. And the litter could alleviated the influence of acid rain on the content of soil nutrientand the quantity of microorganisms.