Soil Acidification Inducing Degradation Of Chinese Hickory (Carya Cathayensis) Forests And Its Amelioration

Degradation of Chinese hickory?Carya cathayensis?forests has become a serious problem: tree growth impairment is very common at present.And soil acidification is considered the key cause.Therefore,it is essential to explore the underlying mechanisms.Two field soil surveys,a lab incubation experiment and a field trial were set correspondingly to clarify the incidence and severity of soil acidification,and to find countermeasures.The main results were as follows:?1?Soil survey from the seven towns of Linan?the majority of Chinese hickory growth area?showed that soil pH varied from 4.2 to 7.5,with mean of 5.2,and there was a proportion of 75% of the soil with pH <5.5.And 91% of the frorest soils were with soil hydrolytic nitrogen >80.0 mg·kg^-1.But there were 63% of forests soil available phosphorus <10.0 mg·kg^-1,and 51% of the research area with soil available potassium <80.0 mg·kg^-1.?2?The soil survey results from different degradation degrees of Chinese hickory forests showed that soil pH of severe degradated forest land was 4.63,and exchangeable Al³⁺ was 5.43 cmol₊·kg^-1.The soil OTU of severe degradation degree forests was decreased by 48.5%.?3?The results of incubation experiment showed that the four materials,namely biological organic fertilizer?BOF?,BSFA,bamboo biochar?BB?and calcium magnesium phosphate fertilizer?CMPF?,all had great effect on soil acidification amelioration and nutrient supply.Soil pH streated with BOF+CMPF and BSFA+CMPF were increased by 1.14 and 1.05 units compared with the control,and soil exchangeable Al³⁺ was decreased by 98.5% and 93.1%,respectively.?4?The field trial results showed that BB,BOF,BSFA not only provided available nutrients,but moreover significantly increased soil pH by 1.46,1.09 and 0.96 units compared with the control,and soil exchangeable Al³⁺ decreased by 90%,66% and 86%,respectively.Three organic materials increased the yield of Chinese hickory followed the order of BSFA>BOF>BB.Results from present study indicates that there needs to control of nitrogen fertilizer application urgently,and soil acidification amelioration strategies such as organic fertilizer?BOF,BSFA?application need to be made to promote healthy growth of Chinese hickory trees.