| Castanopsis hystrix is an evergreen tree of Fagaceae Castanopsis,a rare native tree species in Guangxi,as its grow fastly,and straight excellent features,it has been planted in a large scale.In recent years,the forest fertilization has become an important afforestation technology,fertilization of trees can not only promote the nutritional status of trees,also can effectively improve the soil fertility of woodland,promote the productivity of forest land.However,there were few experiment research reports about N?P?K fertilizer on Castanopsis hystrix,so the study was based on the 2-year-old young forest of Castanopsis hystrix in Gaofeng Forest Farm,Nanning,Guangxi,using the nitrogen(N),phosphorus(P),potassium(K)three-factor and three-level orthogonal desing to study the effects of N?P and K fertilizers on the growth physiology and soil properties of the young plant of Castanopsis hystrix.The purpose of this study was researching the effects of this fertilizer application on the growth characteristics,physiological characteristics and forest soil of Castanopsis hystrix young forest.By comprehensive test results,screen out the optimum of N?P?K ratio for the actual production,in order to develop a fertilizer with the most promotion effect and promote the fertilization forestry industry sustainable development to provide a certain scientific theoretical basis.The main results are as follows:(1)The best effect on height,DBH,North and South crown and total biomass was T5(N2P2K3 N:87.5 g,P2O5:162.5 g,K2O:75.0 g),the strongest effect on the East and West crown was T6(N2P3K1 N:87.5g,P2O5:243.8g,K2O:25.0 g),the average leaf area of the fertilizer treatment was between 13.99?29.83cm2.The influence of N?P and K on the ascent indexes of the three developing factors was different.N had the greatest influence on height,breast diameter and average single leaf area,and P had the greatest influence on crown width(North South crown and East West crown),while K had the greatest influence on total biomass.In general,the develop of young forests with medium level of N(N:87.5 g),middle and higher level of P(P2O5:162.5g/243.8g),medium and low level of K(25.0g/50.0g)was better.(2)From the results of physiological indexes,the best effect of fertilization on the content of chlorophyll was K in early stage,but in the later period,it was P.N was the most important factor affecting soluble protein and soluble sugar.The ratio of N?P and K in leaves increased significantly,T4(N2P1K2 N:87.5g,P2O5:81.3g,K2O:50.0g)had the highest content of N,T6(N2P3K1 N:87.5 g,P2O5:243.8g,K2O:25.0g)had the highest content of P,T7(N3P1K3 N:131.3g,P2O5:81.3g,K2O:75.0 g)had the highest content of K.(3)Formulaed fertilization had a significant effect on woodland soil of Castanopsis hystrix forest,except for the decrease of soil pH.The organic matter,soil nitrogen,phosphorus and potassium,microbial biomass and other soil enzyme activities under the fertilizer treatment were improved to varying degrees,but the above nutrition indicators showed a declining trend in CK.The best performance of the overall fertilizer efficiency was T5(N2P2K3 N:87.5g,P2O5:162.5g,K2O:75.0g),the contents of soil organic matter,total phosphorus,nitrate nitrogen,ammonium nitrogen and available potassium were the highest.(4)From the correlation analysis result showed that there was a strong positive correlation between growth index,physiological index and soil characteristic index of Castanopsis hystrix forest,however,there was still a small number of indicators showing no significant correlation,as pH had only a significant correlation with catalase activity.Generally speaking,there was a close correlation between the growth indexes.physiological indexes and the indicators of soil nutrient status of Castanopsis hystrix.The membership functions of these indexes were fuzzy comprehensive evaluation,the maximum of the average value of the membership function was T5(N2P2K3 N:87.5g,P2O5:162.5g,K2O:75.0g),coincided with the results of various indexes.Therefore,the response of young forest of Castanopsis hystrix to treatment of T5 was best.It can not only promote the growth and development of trees,but also improve the soil nutrient status of forest land. |
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